Igcse Chemistry Flashcards
State the method used to obtain red food dye from a mixture of food dyes
paper chromatography
State the method used to obtain water from salt water
simple distillation
Draw a diagram to show equipment used in simple distillation
For what process is this equipment used?
State the method used to obtain kerosene from a crude oil.
fractional distillation
Draw the equipment used in fractional distillation in the lab
For what process is this equipment used?
Explain how fractional distillation is used to separate a mixture of different liquids
The different liquids have different boiling points
Describe how pure salt can be obtained from rock salt
1) Grind rock salt into a fine powder. 2) Add powder to hot water and stir to dissolve salt. 3) Filter mixture. Salt solution passes through the filter paper leaving behind the sand. 4) Boil filtrate to evaporate some of the water. 5) Leave saturated solution to cool so that crystals of salt form. 6) Filter cold mixture to separate the crystals from the remaining solution.
Ethanol is a flammable liquid. Suggest how it could be heated safely
Use a water bath
Explain how a chromatogram shows that different dyes are different from each other
Each dyes has a different mixture
State the expression for calculating molar concentration
Molar concentration = Amount (in moles)/volume (in dm^³)
Describe how you would carry out a flame test
Put solid onto a wire. Put into a blue flame
How would you test for the ammonium ion?
Add sodium hydroxide. If ammonium ions were present, ammonia gas will form which will turn damp red litmus paper blue
Describe how you would test for Cu²⺠ions
Add sodium hydroxide and a blue precipitate will form
Describe how you would test for Fe²⺠ions
Add sodium hydroxide and a green precipitate will form
Write a word equation for the reaction between sodium hydroxide and iron(II) sulfate
sodium hydroxide + iron(II) sulfate -> iron (II) hydroxide + sodium sulfate
Describe how you would test for Fe³⺠ions
Add sodium hydroxide and a brown precipitate will form
What 2 things are added to a solution to test for chloride ions? What is observed if they are present?
Add dilute nitric acid and silver nitrate. A white precipitate of silver chloride is formed.
Describe the test for bromide ions.
Add dilute nitric acid and silver nitrate. A cream precipitate of silver bromide is formed.
After adding nitric acid and silver nitrate to a solution containing iodide ions, what colour precipitate is formed?
A yellow precipitate (of silver iodide) is formed.
Why is hydrochloric acid added before barium chloride solution in testing for sulfate ions?
To remove carbonate ions
Describe how you would test for sulfate ions
Add dilute HCl, followed by BaClâ. A white precipitate will form
Write an chemical equation for the reaction between barium chloride and lithium sulfate (LiâSOâ). Include state symbols. Also, what would you see?
BaClâ (aq) + LiâSOâ (aq) -> BaSOâ (s)+ 2LiCl (aq). Observe a white precipitate of barium sulfate.
Describe how you would test for carbonate ions, COâ²â»
Add nitric acid and see if carbon dioxide bubbles form
Describe the test for ammonia gas
Turns damp red litmus paper blue
State the expression for calculating % yield. (Triple science only!)
% yield = (actual amount of products/theoretical amount of products) x100
Describe the chemical test for water
Add water to anhydrous copper(II) sulfate which will change from white to blue if water is present
The addition of water to anhydrous copper sulfate can be used to test for the presence of water. The reaction is reversible. What is the word equation? Describe the colour change.
anhydrous copper sulfate (white) + water <-> hydrated copper sulfate (blue)
Ammonia and hydrogen chloride react together in a reversible reaction to produce a white solid. What are the word and symbol equations?
ammonia + hydrogen chloride <-> ammonium chloride NHâ + HCl <-> NHâCl
State two features of a reaction that is in dynamic equilibrium
1) The rate of the forward reaction is equal to the rate of the backward reaction. 2) There is no overall change in concentrations.
Predict what will happen to the equilibrium position in the following reaction when the pressure is increased. Give a reason for your prediction: CHâ(g) + HâO(g) <-> CO(g) + 3Hâ(g) ÎH = +210 kJ molâ»1
Equilibrium will move to the left because there are fewer molecules on the left hand side
Predict what will happen to the equilibrium position in the following reaction when the temperature is increased. Give a reason for your prediction: CHâ(g) + HâO(g) <-> CO(g) + 3Hâ(g) ÎH = +210 kJ molâ»1
Equilibrium will move to the right because the forward reaction is endothermic
Predict what will happen to the equilibrium position in the following reaction when the temperature is increased. Give a reason for your prediction: CO(g) + HâO(g) <-> COâ(g) + Hâ(g) ÎH = -42 kJ molâ»1
Equilibrium will move to left the because the reaction is exothermic
Predict what will happen to the equilibrium position in the following reaction when the temperature is decreased. Give a reason for your prediction: CO(g) + 2Hâ(g) <-> CHâOH(g) ÎH = -91 kJ molâ»1
Equilibrium will move to right the because the reaction is exothermic
Predict what will happen to the equilibrium position in the following reaction when the pressure is decreased. Give a reason for your prediction: CO(g) + 2Hâ(g) <-> CHâOH(g) ÎH = -91 kJ molâ»1
Equilibrium will move to left the because there are more molecules on the left hand side
State the raw materials used in the manufacture of ammonia
nitrogen from air and hydrogen from natural gas
State a use for Nâ
making ammonia
The following reaction is used to manufacture ammonia in the Haber process: Nâ + 3Hâ -> 2NHâ ÎH = -92KJ/mol. The reaction is carried out at 450â°C but the reaction would be faster if a higher temperature were used. Suggest why a higher temperature is not used in the Haber process
Yield would decrease and energy costs would increase
How is ammonia separated from unreacted hydrogen and nitrogen in the Haber process?
The reaction mixture is cooled until the ammonia condenses into a liquid
State the uses of ammonia
manufacture of nitric acid and fertilisers
Suggest the names of two elements, other than nitrogen, that are likely to be present in NPK fertiliser
potassium and phosphorous
Write a chemical equation for the reaction between ammonia and nitric acid
NHâ + HNOâ -> NHâNOâ
State the raw materials used in the manufacture of sulfuric acid. (Triple science only!)
sulphur (from ores) and oxygen (from air)
Describe the manufacture of sulfuric acid by the contact process. (Triple science only!)
1) Making of sulfur dioxide: S + Oâ -> SOâ, 2) Reversible step: 2SOâ + Oâ <-> 2SOâ (exothermic), 3) HâSOâ + SOâ -> HâSâOâ, 4) HâSâOâ + HâO -> 2HâSOâ
State the catalyst used for the manufacture of sulfuric acid by the contact process. (Triple science only!)
Vanadium(V) oxide
State the uses of sulfuric acid. (Triple science only!)
manufacture of detergents, fertilisers and paints
In Chemistry, what is the meaning of the word Group? What does that tell us about the electron configuration?
A Group is a vertical column of similar elements (same number of electrons in the outer shell)
In Chemistry, what is the meaning of the word Period? What does that tell us about the electron configuration?
A Period is a horizontal row of elements (same number of electron shells)
Where are the metals in the Periodic Table? Where are the Non-Metals?
Metals on the left of the Periodic Table. Non-Metals on the top-right, plus Hydrogen.
Why do elements in the same group of the periodic table have the same chemical properties?
Elements in the same group of the periodic table have the same number of electrons in their outer shell
Explain, in terms of the arrangement of electrons in its atoms, why neon is very unreactive
Neon has 8 electrons in the outer shell, so it is full. Therefore it does not easily gain or lose electrons
Write the chemical equation for the reaction betweem sodium and water
2Na + 2HâO -> 2NaOH + Hâ
State 5 observations when potassium reacts with water
1) fizzing occurs 2) potassium moves around 3) potassium melts 4) lilac flame is seen 5) potassium disappears 6) potassium floats
Complete the equation for the reaction by inserting the state symbols: 2Li(....) + 2HâO(....) -> 2LiOH(...) + Hâ(....)
2Li(s) + 2HâO(l) -> 2LiOH(aq) + Hâ(g)
State 4 observations when sodium reacts with water
1) fizzing occurs 2) sodium moves around 3) sodium melts 4) sodium disappears 5) sodium floats
How should group 1 elements be stored
Under oil
Describe the relative reactivities of the elements in Group 1
The reactivity increases as you go down the group, e.g. Li<Na<K<Rb
Explain, by referring to the electronic configurations of sodium and potassium, why potassium is more reactive than sodium. (Triple science only!)
Sodium has the electronic configuration 2,8,1 and potassium has 2,8,8,1. The outer electron lost from potassium is further from the nucleus therefore the electron is less attracted by the nucleus
State the colour and physical state of bromine at room temperature
Orange brown liquid
Suggest how the reactivity of astatine compares to that of iodine. Explain your answer.
Astatine is less reactive because group 7 elements get less reactive with increasing atomic number.
Why does chlorine react with hydrogen bromide?
Chlorine is more reactive and so displaces the bromine.
Hydrogen bromide is reacted with chlorine to form bromine. Write a chemical equation.
2HBr + Clâ -> 2HCl + Brâ
State the colour change observed when bromine is added to an aqueous solution of potassium iodide
Colourless to brown
Why would there be no reaction when iodine was added to sodium bromide solution?
Iodine as it is less reactive than bromine
Name the substance with the brown colour that forms whem chlorine is added to potassium iodide solution
Iodine as it is less reactive than chlorine
Identify the species that is oxidised in the following reaction. Explain your answer: 2Brâ» + Clâ -> 2Clâ» + Brâ
Bromide. Loses electrons
Identify the species that is reduced in the following reaction. Explain your answer: 2Brâ» + Clâ -> 2Clâ» + Brâ
Chlorine. Gains electrons
When chlorine gas is bubbled into an aqueous solution of potassium iodide, the colourless solution turns brown. Complete the following ionic equation: Clâ(g)+ ___Iâ»(aq) -> 2Clâ»(aq) + ___(aq)
Clâ(g) + 2Iâ»(aq) -> 2Clâ»(aq) + Iâ(aq)
Describe the test for chlorine gas
Turns moist litmus paper white (bleaches)
Describe, in terms of electrons, the formation of sodium chloride
An atom of sodium loses one electron. An atom of chlorine gains one electron
Explain the term ionic bond
An ionic bond is the strong electrostatic attraction between oppositely charged ions
Explain, in terms of structure and bonding, why sodium chloride has a very high melting point
NaCl has a giant ionic structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break
Explain, in terms of structure and bonding, why magnesium oxide has a higher melting point than sodium chloride (Triple science only!)
NaCl and MgO both have a giant ionic structure with strong electrostatic forces between oppositely charged ions. The Ions in MgO have a charge of 2 and -2, but in NaCl the charges are 1 and -1. So the bonds in MgO require more energy to break
Explain why magnesium oxide has a higher melting point than sodium chloride. (Triple science only!)
Mg²⺠and O²⻠ions have a higher charge than sodium and chloride therefore the electrostatic forces between the ions are much stronger. This requires more energy to break.
Describe the structure of an ionic compound, e.g NaCl. (Triple science only!)
A giant structure held together by the attraction between oppositely charged ions
Draw a diagram to represent the positions of the ions in a crystal of sodium chloride.
A - sodium ions. B - Chloride ions
Describe the formation of a covalent bond
The sharing of a pair of electrons between two nuclei
Give the definiton of a covalent bond
Strong attraction between a shared pair of electrons and two nuclei
Explain the term covalent bond
Strong attraction between a shared pair of electrons and two nuclei
If a substance has a simple molecular structure, what physical state might it be at room temperature?
Gas or liquid (low melting point)
Explain why nitrogen gas, Nâ, is a gas at room temperature
Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Explain why Silica, SiOâ is a solid with a high melting point
Silica has a giant covalent structure with many strong covalent bonds that need a lot of energy to break
Buckminsterfullerene has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Suggest why buckminsterfullerene, C60, has a low melting point.
Explain, in terms of its structure, why graphite can act as a lubricant. (Triple science only!)
Graphite has weak intermolecular forces of attraction between layers. These layers can slide over each other
Explain, in terms of its structure, why graphite can conduct electricity. (Triple science only!)
Graphite has delocalised electrons which can move
Describe the structure of metals
Metals have a giant regular structure of positive ions surrounded by a sea of delocalised electrons
Define metallic bonding
The electrostatic attraction between a regular array of positive ions and the sea of delocalised electrons
Explain why metals are good conductors of electricity
Metals have delocalised electrons which are free to move
Explain why metals are ductile/malleable
Metals have layers of atoms that can slide over each other
Explain what is meant by electric current
The rate of flow of charge particles (e.g. of electrons or ions)
Why do covalent compounds (e.g HâO) not conduct electricity?
There are no charged particles that are free to move
Why do ionic compounds conduct electricity only when molten or in solution?
When solid the ions are held in place. When molten or in solution the ions are free to move
What type of reaction is used to form nylon? (Triple science only!)
Condensation polymerisation
During condensation polymerisation, what else forms other than the polymer? (Triple science only!)
A small molecule such as Hâ0 or HCl
Describe, in terms of electrons, the formation of sodium chloride
An atom of sodium loses one electron. An atom of chlorine gains one electron
Explain the term ionic bond
An ionic bond is the strong electrostatic attraction between oppositely charged ions
Explain, in terms of structure and bonding, why sodium chloride has a very high melting point
NaCl has a giant ionic structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break
Explain, in terms of structure and bonding, why magnesium oxide has a higher melting point than sodium chloride (Triple science only!)
NaCl and MgO both have a giant ionic structure with strong electrostatic forces between oppositely charged ions. The Ions in MgO have a charge of 2 and -2, but in NaCl the charges are 1 and -1. So the bonds in MgO require more energy to break
Explain why magnesium oxide has a higher melting point than sodium chloride. (Triple science only!)
Mg²⺠and O²⻠ions have a higher charge than sodium and chloride therefore the electrostatic forces between the ions are much stronger. This requires more energy to break.
Describe the structure of an ionic compound, e.g NaCl. (Triple science only!)
A giant structure held together by the attraction between oppositely charged ions
Draw a diagram to represent the positions of the ions in a crystal of sodium chloride.
A - sodium ions. B - Chloride ions
Describe the formation of a covalent bond
The sharing of a pair of electrons between two nuclei
Give the definiton of a covalent bond
Strong attraction between a shared pair of electrons and two nuclei
Explain the term covalent bond
Strong attraction between a shared pair of electrons and two nuclei
If a substance has a simple molecular structure, what physical state might it be at room temperature?
Gas or liquid (low melting point)
Explain why nitrogen gas, Nâ, is a gas at room temperature
Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Explain why Silica, SiOâ is a solid with a high melting point
Silica has a giant covalent structure with many strong covalent bonds that need a lot of energy to break
Buckminsterfullerene has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Suggest why buckminsterfullerene, C60, has a low melting point.
Explain, in terms of its structure, why graphite can act as a lubricant. (Triple science only!)
Graphite has weak intermolecular forces of attraction between layers. These layers can slide over each other
Explain, in terms of its structure, why graphite can conduct electricity. (Triple science only!)
Graphite has delocalised electrons which can move
Describe the structure of metals
Metals have a giant regular structure of positive ions surrounded by a sea of delocalised electrons
Define metallic bonding
The electrostatic attraction between a regular array of positive ions and the sea of delocalised electrons
Explain why metals are good conductors of electricity
Metals have delocalised electrons which are free to move
Explain why metals are ductile/malleable
Metals have layers of atoms that can slide over each other
Explain what is meant by electric current
The rate of flow of charge particles (e.g. of electrons or ions)
Why do covalent compounds (e.g HâO) not conduct electricity?
There are no charged particles that are free to move
Why do ionic compounds conduct electricity only when molten or in solution?
When solid the ions are held in place. When molten or in solution the ions are free to move
What type of reaction is used to form nylon? (Triple science only!)
Condensation polymerisation
During condensation polymerisation, what else forms other than the polymer? (Triple science only!)
A small molecule such as Hâ0 or HCl
Describe, in terms of electrons, the formation of sodium chloride
An atom of sodium loses one electron. An atom of chlorine gains one electron
Explain the term oxidation
Oxidation is the loss of electrons (the term is also used for the gain of oxygen)
Explain the term reduction
Reduction is the gain of electrons (the term is also used for the loss of oxygen)
Describe the structure of metals
Metals have a giant regular structure of positive ions surrounded by a sea of delocalised electrons
Define metallic bonding
The electrostatic attraction between a regular array of positive ions and the sea of delocalised electrons
Explain why metals are good conductors of electricity
Metals have delocalised electrons which are free to move
Explain why metals are ductile/malleable
Metals have layers of atoms that can slide over each other
Explain what is meant by electric current
The rate of flow of charge particles (e.g. of electrons or ions)
Why do covalent compounds (e.g HâO) not conduct electricity?
There are no charged particles that are free to move
Why do ionic compounds conduct electricity only when molten or in solution?
When solid the ions are held in place. When molten or in solution the ions are free to move
How could you determine if a liquid is an electrolyte?
Put it in a circuit including a bulb. If the bulb light then the liquid is an electrolyte
Explain what is meant by electrolysis
The breakdown of a substance using electricity
What is the charge of the anode?
positive
What is the charge of the cathode?
negative
Write an equation to show the formation of the product at the cathode during the electrolysis of copper chloride
Cu²⺠+ 2e⻠-> Cu
Write an equation to show the formation of the product at the anode during the electrolysis of copper chloride
2Clâ» -> Clâ + 2eâ»
Suggest why a small amount of dilute acid is added to water before it is electrolysed
increases electrical conductivity
During the electrolysis of water, oxygen gas is given off. The formation of this gas can be represented by the ionic equation: ....OHâ» ->....HâO + ....Oâ + ....eâ» (Triple science only!)
4OHâ» ->2HâO + Oâ + 4eâ»
Name the product formed at the cathode during the electrolysis of water. (Triple science only!)
hydrogen
The overall equation for the decomposition of water is: 2HâO(l) -> 2Hâ(g) + Oâ(g) Use this equation to explain why the volume of hydrogen collected should be twice that of the volume of oxygen. (Triple science only!)
The number of moles of Hâ are twice that of oxygen
Write the ionic half-equation for the reaction that takes place at the anode during the electrolysis of lead(II) bromide
2Brâ» -> Brâ + 2eâ»
Write the ionic half-equation for the reaction that takes place at the cathode during the electrolysis of lead(II) bromide
Pb²⺠+2e⻠-> Pb
What is a Faraday? (Triple science only!)
A Faraday is the charge on a mole of electrons (96500 Coulombs)
During the electrolysis of sodium chloride solution, chlorine gas is produced. The equation for its formation is: 2Clâ» -> Clâ + 2eâ» Calculate the quantity of electricity, in coulombs, needed to produce 18cm³ of chlorine gas. (Triple science only!)
Amount of Clâ = 18/24000 = 0.00075mol. Charge = 0.00075 x 965000 x 2 = 144.45C
An experiment investigates which of metals X and Z is more reactive. The result is X + ZSOâ -> XSOâ + Z. Which metal is more reactive?
X. This is a displacement reaction.
State the meaning of the term redox
A reaction involving both reduction and oxidation
State the meaning of the term oxidising agent
A substance that gives oxygen or removes electrons (it is itself reduced)
State the meaning of the term reducing agent
A substance that takes oxygen or gives electrons (it is itself oxidised)
Describe the test for hydrogen gas
Use a lit splint to see if the gas pops
Describe the test for oxygen gas
Use a glowing splint and see if it relights
Describe the test for chlorine gas
Turns moist litmus paper white (bleaches)
During the electrolysis of aluminium oxide, describe how the operating temperature is kept low
aluminium oxide is dissolved in cryolite which melts at a lower temperature
Why is cryolite used in the electrolysis of aluminium oxide?
cryolite is used as a solvent to decrease the operating temperature
Explain why the operating temperature would need to be very high if pure aluminium oxide were used and the electrolyte during the electrolysis of aluminium oxide
aluminium oxide has a very high melting point
Why do the electrodes need to be replaced regularly during the electrolysis of aluminium oxide?
oxygen formed at the anode reacts with the carbon in the anode. C + Oâ -> COâ
State the major reason for the high cost of extracting alumimium during the electrolysis of aluminium oxide
large amounts of electricity
The chemical equations for the two reactions that occur during the extraction of aluminium are A: Al³⺠+ 3e¯ -> Al and B: C + Oâ -> COâ. State and explain which species in the reactions are oxidation or reduction
A: Al³⺠is reduced because it gains electrons. B: C is oxidised because it gains oxygen
Write ionic half-equations for the reactions at the electrodes in aluminium extraction
Al3⺠+ 3eâ» -> Al and 2O²⻠-> Oâ + 4eâ»
Why does this equation represent a reduction reaction? Al³⺠+ 3e⻠-> Al
Al3⺠gains electrons
What is the formula of aluminium oxide?
AlâOâ
In the electrolysis of NaCl, what are the anode and cathode made of? (Triple science only!)
anode = titanium. Cathode = iron
The solution formed after the electrolysis sodium chloride solution was tested with the indicator phenolphthalein. The indicator turned pink. Explain this result. (Triple science only!)
The solution is alkali (contains sodium hydroxide)
In the electrolysis of brine, why is thelectrode made out of titanium? (Triple science only!)
To prevent it reacting with the chlorine
Write the two ionic half-equations for the reactions that occur during the electrolysis of sodium chloride solution. (Triple science only!)
2H⺠+ 2eâ» -> Hâ and 2Clâ» -> Clâ + 2eâ»
State the uses of sodium hydroxide. (Triple science only!)
manufacture of bleach, paper and soap
State the uses of chlorine. (Triple science only!)
sterilising water supplies and the manufacture of bleach and hydrochloric acid
What is the name of the colourless gas that is formed between the reaction of chlorine and hydrogen?
Hydrogen chloride
What is the name of the acid that is formed when hydrogen chloride gas dissolves in water?
Hydrochloric acid
Why is HCl acidic when dissolved in water?
As water is polar the HCl molecule dissociates, forming H⺠and Cl⻠ions.
Why is HCl not acidic when dissolved in methyl benzene?
As methyl benzene is not polar the molecules separate but don't form ions.
State the colour of litmus in acidic and alkaline solutions
acidic = red alkali = blue
State the colour of phenolphthalein in acidic and alkaline solutions
acidic = colourless alkali = pink
State the colour of methyl orange in acidic and alkaline solutions
acidic = red alkali = yellow
What is an acid?
An acid is a source of hydrogen ions, Hâº
What is an alkali?
An alkali is a source of hydroxide ions, OHâ»
acid + base ->
acid + base -> salt + water
acid + alkali ->
acid + alkali -> salt + water
acid + metal ->
acid + metal -> salt + hydrogen
acid + metal carbonate ->
acid + metal carbonate -> salt + carbon dioxide + water
sulfuric acid + copper oxide ->
sulfuric acid + copper oxide -> copper sulfate + water
hydrochloric acid + sodium hydroxide ->
hydrochloric acid + sodium hydroxide -> sodium chloride + water
hydrochloric acid + magnesium ->
hydrochloric acid + magnesium -> magnesium chloride + hydrogen
nitic acid + calcium carbonate ->
nitic acid + calcium carbonate -> calcium nitrate + carbon dioxide + water
Give the name of the substance which has the formula HCl
hydrochloric acid
Give the formula of sulfuric acid
HâSOâ
State the solubility rule for sodium, potassium and ammonium salts
all common sodium, potassium and ammonium salts are soluble
State the solubility rule for nitrate salts
all nitrates are soluble
State the solubility rule for chloride salts
all are soluble, except silver chloride
State the solubility rule for sulfate salts
all sulfates are soluble, except those of barium and calcium
State the solubility rule for carbonates salts
all carbonates are insoluble, except those of sodium, potassium and ammonium
What is the meaning of the word mole in Chemistry?
A mole is the amount of a substance found in its relative formula mass in grams (e.g. in 24g of Magnesium)
What is avagadro's number, and to what is it equivalent? (Triple science only!)
6 x 10^²³. It is equivalent to the number of atoms in 12 g of 12 C.
Using relative atomic mass (Aáµ£) and relative formula mass (Máµ£), complete the following expression: mass =
amount (in moles) x Mr
Using relative atomic mass (Aáµ£) and relative formula mass (Máµ£), complete the following expression: Máµ£ =
mass / amount (in moles)
What is the meaning of the term Molar Volume? (Triple science only!)
The volume of 1 mole of gas at r.t.p is called the molar volume (24dm³ or 24000cm³)
State the expression for calculating molar volume of a gas. (Triple science only!)
Molar volume = amount (in moles) x 24 dm³ or 24,000 cm³
State the conditions needed for the manufacture of ethanol using ethene and steam. (Triple science only!)
Temp: 300°C, Pressure: 60 atm and Catalyst: Phosphoric acid, HâPOâ
State the raw materials needed for the manufacture of ethanol using ethene and steam. (Triple science only!)
Crude oil and water
Write the chemical equation for manufacture of ethanol by passing ethene and steam. (Triple science only!)
CâHâ +Hâ0 ->CâHâ 0H
State the conditions needed for the manufacture of ethanol by the fermentation of sugars. (Triple science only!)
Temp: 30°C, Catalyst: zymase (enzyme found in yeast), Anaerobic conditions, i.e no oxygen
State the name of the reaction used to manufacture ethanol from sugars. (Triple science only!)
Fermentation
Write the chemical equation for manufacture of ethanol by the fermentation of sugars. (Triple science only!)
CâHââOâ -> 2CâHâ OH + 2COâ
What are the advantages/disadvantages of using the fermentation of glucose to manufacture ethanol. (Triple science only!)
Advantages: Uses renewable resources, e.g sugar cane. Uses low temp and pressure therefore low energy input. Disadvantages: Uses batch process which is inefficient. Slow rate of reaction. Impure product.
What are the advantages/disadvantages of using the hydration of ethene to manufacture ethanol. (Triple science only!)
Advantages: Uses continuous process which is efficient. Fast rate of reaction. Pure product. Disadvantages: Uses finite resources, e.g crude oil cane. Uses high temp and pressure therefore high energy input.
State the conditons needed for the dehydration of ethanol to ethene. (Triple science only!)
Hot aluminium oxide catalyst
Write the chemical equation for the dehydration of ethanol. (Triple science only!)
CâHâ 0H -> CâHâ +Hâ0
What is meant by the term exothermic?
A reaction in which heat energy is given out (surroundings get hotter)
What is meant by the term endothermic?
A reaction in which heat energy is taken in (surroundings get colder)
Explain why experimental values of enthalpy change differ from theoretical values
Heat energy is lost to the surroundings. Not all the reactants are used up.
What does the symbol ÎH mean
enthalpy (energy) change
Draw an energy level diagram for an exothermic reaction and use ÎH to represent the enthalpy change
Explain, in terms of making and breaking bonds, why a reaction could be exothermic
The energy need to break the bonds is less than the energy released to make the bonds
Explain, in terms of making and breaking bonds, why a reaction could be endothermic
The energy need to break the bonds is more than the energy released to make the bonds
Explain why carbon monoxide is dangerous to humans
It is poisonous because it reduces the capacity of the blood to carry oxygen
In car engines, sparks cause the formation of some gases which contribute to acid rain. What are these gases?
Oxides of nitrogen
Why can nitrogen react with oxygen in a car engine?
The temperature is very high
Describe how nitrogen oxides and sulfur dioxide contribute to acid rain
Nitrogen oxides created in hot car engines and sulfur dioxide released when fossil fuels are burned combine with water in the atmosphere to form acidic solutions
Write the chemical equation for sulfur dioxide dissolving in water to form acid rain
SOâ + HâO -> HâSOâ
Describe the problems caused by acid rain
Acid rain damages plant life and life in lakes. It also corrodes limestone and some metals.
Explain the term homologous series
A homologous series is a family of compounds with 1) the same general formula 2) similar chemical properties 3) trends in their physical properties
Explain the term hydrocarbon
A molecule containing only hydrogen and carbon
Explain the term saturated
A molecule containing only single bonds
Explain the term unsaturated
A molecule containing a carbon-carbon double bond
Explain the term general formula
A formula to work out the number of each type of atom in a molecule
Explain the term isomerism
Molecules with the same molecular formula but with a different structure
State the names and molecular formulae of the first 5 alkanes
methane (CHâ), ethane (CâHâ), propane (CâHâ), butane (CâHââ), pentane (Câ Hââ)
Write a chemical equation for the complete combustion of propane
CâHâ + 5Oâ -> 3COâ + 4HâO
Recall the products of the complete combustion of alkanes
Carbon dioxide and water
Recall the products of the incomplete combustion of alkanes
Carbon, carbon monoxide, carbon dioxide and water
What is the name given to the type of reaction that occurs when ethane reacts with bromine under UV light
Substitution
Write the word equation for the reaction between methane and bromine
methane + bromine -> bromomethane + hydrogen bromide
Write the chemical equation for the reaction between methane and bromine
CHâ + Brâ -> CHâBr +HBr
State the names and molecular formulae of the first 3 alkenes
ethene (CâHâ), propene (CâHâ), butene (CâHâ)
Draw the displayed formulae for the two straight chain isomers of butene. Name these two isomers
but-1-ene and but-2-ene
State the colour change in the reaction of an alkene with bromine water
Orange to colourless
What is crude oil?
A mixture of hydrocarbons
Explain how crude oil is separated into fractions
Crude oil is separated by fractional distillation. Crude oil is heated and the oil evaporates. It then goes into the tower. As the vapours rise up the tower the temperature falls. Different sized fractions condense at different heights because they have different boiling points. Smaller molecules condense high up the tower. Larger molecules condense low down in the tower. Then the fractions are collected.
Recall the names of the main fractions obtained from crude oil
Refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen
Recall a use of refinery gases
Bottled gas
Recall a use of gasoline
Fuel for cars
Recall a use of kerosene
Fuel for aeroplanes
Recall a use of diesel
Fuel for lorries
Recall a use of fuel oil
Fuel for ships
Recall a use of bitumen
Surfacing roads
Describe the trend in boiling points of the main fractions in crude oil
Boiling point increases as the number of carbon atoms (chain length) increase
Describe the trend in viscosity of the main fractions in crude
Viscosity increases as the number of carbon atoms (chain length) increase
Which fraction of crude oil has the lowest boiling point?
Refinery gases
What is meant by the term viscosity?
The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.
Explain why cracking is an important process in the oil industry
Cracking converts long chain hydrocarbons into short chain hydrocarbons. Crude oil contains a surplus long chains. Shorter chain hydrocarbons are in greater demand, e.g. petrol. Cracking also produces alkenes which are used in making polymers and ethanol.
What is cracking?
The breaking down of long-chain alkanes into alkenes and shorter-chain alkanes
State the conditions for the cracking of hydrocarbons
Aluminium oxide catalyst heated to 600°C
Write a chemical equation for the cracking of decane
CââHââ -> CâHâ + CâHââ
Explain what is an addition polymer
An addition polymer is large molecule made by adding many small molecules (each containing a double bond) to form one much larger molecule
Explain what is a monomer
Monomers are the many small molecules (such as ethene) which add together to make a polymer
Describe, in terms of structure and bonding, what happens when ethene molecules are converted into poly(ethene)
One bond in the double bond breaks. Monomers join together to form a long chain. Polymer contains only single bonds
State the uses of poly(ethene)
Plastic bags and bottles
State the uses of poly(propene)
Plastic crates and ropes
State uses for poly(chloroethene). (Triple science only!)
Plastic piping and cable insulation
What is meant by the term biodegradable?
The break down of a substance by microorganisms
Explain why addition polymers are hard to dispose of
They are inert as they have strong C-C bonds. This makes them non-biodegradeable.
Describe the structure of metals
Metals have a giant regular structure of positive ions surrounded by a sea of delocalised electrons
Define metallic bonding
The electrostatic attraction between a regular array of positive ions and the sea of delocalised electrons
Explain why metals are good conductors of electricity
Metals have delocalised electrons which are free to move
Explain why metals are ductile/malleable
Metals have layers of atoms that can slide over each other
In each of these pairs, which metal is more reactive: 1) sodium and copper. 2) iron and calcium. 3) potassium and aluminium
1) sodium 2) calcium 3) potassium
Explain why rusting is described as an oxidation reaction
iron gains oxygen (lose of electrons)
What is reduced in this equation and what is meant by reduction? WOâ + 3Hâ -> W + 3HâO
Tungsten, W losses oxygen
State the meaning of the term redox
A reaction involving both reduction and oxidation
State the meaning of the term oxidising agent
A substance that gives oxygen or removes electrons (it is itself reduced)
State the meaning of the term reducing agent
A substance that takes oxygen or gives electrons (it is itself oxidised)
Describe the conditions under which iron rusts
oxygen and water
What is the chemical name of rust?
hydrated iron(III) oxide
Describe an experiment to show that iron rusts quicker in salt water than rain water
1) Set up tubes containing iron in rain water and in salt water. 2) Set up control tube with iron and no water. 3) record mass of nails. 4) leave tubes for same length of time. 5) measure mass change of nail. 6) repeat experiment
Write the word equation for the formation of rust
iron + oxygen + water -> hydrated iron (III) oxide
State the methods of how the rusting of iron may be prevented
grease, oil, paint, plastic and galvanising
Explain how galvanising prevent rusting
Zinc is more reactive than iron. Zinc reacts with oxygen instead of iron
Name the process used to extract aluminium
electrolysis
Why is aluminium not extracted in the blast furnace?
aluminium is more reactive than carbon
Explain why silicon dioxide reacts with calcium oxide. SiOâ + CaO -> CaSiOâ
SiOâ is acidic and CaO is basic. This is a neutralisation reaction.
The following reaction is important in the extraction of iron in a blast furnace: C + Oâ -> COâ. Name the raw material that reacts with oxygen and state why the reaction is important
Coke. It produces heat
Name the useful compound present in haematite
iron(III) oxide
Name the useful compound present in limestone
calcium carbonate
Write the chemical equation for the reaction that produced heat in the blast furnace
C + Oâ -> COâ
Write the chemical equation for a neutralisation reaction in the blast furnace
SiOâ + CaO -> CaSiOâ
Write the chemical equation for a decomposition reaction in the blast furnace
CaCOâ -> CaO + COâ
Write the chemical equation for the reaction that forms a reducing agent in the blast furnace
C + COâ -> 2CO
State 3 properties that makes iron suitable for saucepans
Good conductor of heat, high melting point and malleable
State 2 properties that makes aluminium suitable for manufacturing aircraft
Low density & resists corrosion
State 2 property that makes aluminium suitable for power cables
Ductile (drawn into a wire), Conducts electricity and low density
State two properties of aluminium that make it suitable for use in food cans
Malleable and low density
Elements in the same group in the Periodic Table have the same number of....
electrons in the outer shell
Describe, in terms of electrons, the formation of sodium chloride
An atom of sodium loses one electron. An atom of chlorine gains one electron
Explain the term ionic bond
An ionic bond is the strong electrostatic attraction between oppositely charged ions
Explain, in terms of structure and bonding, why sodium chloride has a very high melting point
NaCl has a giant ionic structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break
Explain, in terms of structure and bonding, why magnesium oxide has a higher melting point than sodium chloride (Triple science only!)
NaCl and MgO both have a giant ionic structure with strong electrostatic forces between oppositely charged ions. The Ions in MgO have a charge of 2 and -2, but in NaCl the charges are 1 and -1. So the bonds in MgO require more energy to break
Explain why magnesium oxide has a higher melting point than sodium chloride. (Triple science only!)
Mg²⺠and O²⻠ions have a higher charge than sodium and chloride therefore the electrostatic forces between the ions are much stronger. This requires more energy to break.
Describe the structure of an ionic compound, e.g NaCl. (Triple science only!)
A giant structure held together by the attraction between oppositely charged ions
Draw a diagram to represent the positions of the ions in a crystal of sodium chloride.
A - sodium ions. B - Chloride ions
Describe the formation of a covalent bond
The sharing of a pair of electrons between two nuclei
Give the definiton of a covalent bond
Strong attraction between a shared pair of electrons and two nuclei
Explain the term covalent bond
Strong attraction between a shared pair of electrons and two nuclei
If a substance has a simple molecular structure, what physical state might it be at room temperature?
Gas or liquid (low melting point)
Explain why nitrogen gas, Nâ, is a gas at room temperature
Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Explain why Silica, SiOâ is a solid with a high melting point
Silica has a giant covalent structure with many strong covalent bonds that need a lot of energy to break
Buckminsterfullerene has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Suggest why buckminsterfullerene, C60, has a low melting point.
Write the word and chemical equation for the decompostion of hydrogen peroxide, H2O2
hydrogen peroxide -> water + oxygen 2H202 -> 2H20 + O2
State the catalyst used for making oxygen through the decomposition of hydrogen peroxide
manganese(IV) oxide, MnO2
Describe the laboratory preparation of oxygen from hydrogen peroxide
Hydrogen peroxide is added to a flask containing a catalyst of manganese oxide, MnO2. Oxygen is produced and is collected underwater.
What happens to the rate of reaction if the surface area of a solid is INCREASED?
Rate of reaction increases
What happens to the rate of reaction if the concentration of solutions is INCREASED?
Rate of reaction increases
What happens to the rate of reaction if the pressure of gases is INCREASED?
Rate of reaction increases
What happens to the rate of reaction if the temperature is INCREASED?
Rate of reaction increases dramatically
What happens to the rate of reaction if a catalyst is added?
Rate of reaction increases
What is meant by the term activation energy?
The minimum energy that the particles in collision must have if a reaction is going to occur
Explain the effects of increasing the surface area of a solid on the rate of a reaction in terms of particle collision theory
1) more particles exposed 2) more frequent collisions 3) increase rate of reaction
Explain the effects of increasing the concentration of solutions on the rate of a reaction in terms of particle collision theory
1) more particles in same space 2) more frequent collisions 3) increase rate of reaction
Explain the effects of increasing the pressure of gases on the rate of a reaction in terms of particle collision theory
1) more particles in same space 2) more frequent collisions 3) increase rate of reaction
Explain the effects of increasing the temperature on the rate of a reaction in terms of particle collision theory
1) particles have more kinetic energy 2) more frequent and successful collisions 3) increase rate of reaction
What is a catalyst?
A substance that speeds up a chemical reaction without being used up
Explain how a catalyst works
A catalyst provides an alternative pathway with lower activation energy
State the particles that are found within the nucleus of an atom
Protons and neutrons
Explain why atoms are neutral
The numbers of electrons and protons are equal
State the mass of an electron
almost 0
What is meant by the term relative atomic mass, Aáµ£?
The average mass of an atom of an element, relative to 1/12th of the mass of an atom of carbon-12
Explain, in terms of electrons, why isotopes have the same chemical properties
Isotopes have the same number of electrons
What is meant by the term isotope?
Atoms of the same element (same number of protons) but with a different number of neutrons
What is meant by the term mass number?
The number of protons plus the number of neutrons in an atom
What is meant by the term atomic number?
The number of protons in an atom
A sample of bromine contained the two isotopes in the following proportions: bromine-79 = 50.7% and bromine-81 = 49.3%. Calculate the relative atomic mass of bromine
((79x50.7)+(81x49.3))/100 = 79.99
A sample of carbon contained 98.90% carbon-12 and 1.10% carbon-13. Calculate the relative atomic mass of carbon
((12x98.90)+(13x1.10))/100 = 12.01
State the steps for calculating empirical formula
1) mass/Ar. 2) divide by the smallest. 3) Give the ratio has a whole number. 4) State final empirial formula
What colour flames to sulphur, carbon and magnesium produce when they burn in air?
Sulphur = blue, Carbon = yellow/orange, Magnesium = white
Are carbon dioxide and sulphur dioxide acidic or basic?
Acidic as carbon and sulphur are non-metals
Is magnesium oxide acidic or basics?
Basic as magnesium is a metal.
Describe the laboratory preparation of carbon dioxide from calcium carbonate and dilute hydrochloric acid
Hydrochloric acid, HCl, is added to a flask containg calcium carbonate, CaCOâ. Carbon dioxide is produced and is collected using a gas syringe.
Write the word and chemical equation for the thermal decompostion of calcium carbonate, CaCOâ
calcium carbonate -> calcium oxide + carbon dioxide CaCOâ -> CaO + COâ
State two properties of carbon dioxide
Soluble in water. Denser than air
Name two uses of carbon dioxide
Fizzy drinks. Fire extinguishers
Explain why carbon dioxide is used in fizzy drinks
Carbon dioxide is soluble in water
Explain why carbon dioxide is used in fire extinguishers
Carbon dioxide is denser that air
Why is carbon dixoxide, COâ harmful to the environment?
It is a greenhouse gas and may contribute to global warming
Describe the test for carbon dioxide gas
Bubble the gas through limewater and see if it goes cloudy
acid + base ->
acid + base -> salt + water
acid + alkali ->
acid + alkali -> salt + water
acid + metal ->
acid + metal -> salt + hydrogen
acid + metal carbonate ->
acid + metal carbonate -> salt + carbon dioxide + water
sulfuric acid + copper oxide ->
sulfuric acid + copper oxide -> copper sulfate + water
hydrochloric acid + sodium hydroxide ->
hydrochloric acid + sodium hydroxide -> sodium chloride + water
hydrochloric acid + magnesium ->
hydrochloric acid + magnesium -> magnesium chloride + hydrogen
nitic acid + calcium carbonate ->
nitic acid + calcium carbonate -> calcium nitrate + carbon dioxide + water
Give the name of the substance which has the formula HCl
hydrochloric acid
Give the formula of sulfuric acid
HâSOâ
Where are the metals in the Periodic Table? Where are the Non-Metals?
Metals on the left of the Periodic Table. Non-Metals on the top-right, plus Hydrogen.
Name the compound formed when magnesium reacts with oxygen
magnesium oxide
What two observations can be made when a metal reacts with an acid?
Bubbles. Metal disappears.
Hydrogen and helium have both been used in balloons. State one advantage of using helium instead of hydrogen
Helium is not flammable
State the colour of litmus in acidic and alkaline solutions
acidic = red alkali = blue
State the colour of phenolphthalein in acidic and alkaline solutions
acidic = colourless alkali = pink
State the colour of methyl orange in acidic and alkaline solutions
acidic = red alkali = yellow
What is an acid?
An acid is a source of hydrogen ions, Hâº
What is an alkali?
An alkali is a source of hydroxide ions, OHâ»
acid + base ->
acid + base -> salt + water
acid + alkali ->
acid + alkali -> salt + water
acid + metal ->
acid + metal -> salt + hydrogen
acid + metal carbonate ->
acid + metal carbonate -> salt + carbon dioxide + water
sulfuric acid + copper oxide ->
sulfuric acid + copper oxide -> copper sulfate + water
hydrochloric acid + sodium hydroxide ->
hydrochloric acid + sodium hydroxide -> sodium chloride + water
hydrochloric acid + magnesium ->
hydrochloric acid + magnesium -> magnesium chloride + hydrogen
nitic acid + calcium carbonate ->
nitic acid + calcium carbonate -> calcium nitrate + carbon dioxide + water
Give the name of the substance which has the formula HCl
hydrochloric acid
Give the formula of sulfuric acid
HâSOâ
Describe the test for carbon dioxide gas
Bubble the gas through limewater and see if it goes cloudy
Explain the term homologous series
A homologous series is a family of compounds with 1) the same general formula 2) similar chemical properties 3) trends in their physical properties
Explain the term hydrocarbon
A molecule containing only hydrogen and carbon
Explain the term saturated
A molecule containing only single bonds
Explain the term unsaturated
A molecule containing a carbon-carbon double bond
Explain the term general formula
A formula to work out the number of each type of atom in a molecule
Explain the term isomerism
Molecules with the same molecular formula but with a different structure
State the names and molecular formulae of the first 5 alkanes
methane (CHâ), ethane (CâHâ), propane (CâHâ), butane (CâHââ), pentane (Câ Hââ)
Write a chemical equation for the complete combustion of propane
CâHâ + 5Oâ -> 3COâ + 4HâO
Recall the products of the complete combustion of alkanes
Carbon dioxide and water
Recall the products of the incomplete combustion of alkanes
Carbon, carbon monoxide, carbon dioxide and water
What is crude oil?
A mixture of hydrocarbons
Explain how crude oil is separated into fractions
Crude oil is separated by fractional distillation. Crude oil is heated and the oil evaporates. It then goes into the tower. As the vapours rise up the tower the temperature falls. Different sized fractions condense at different heights because they have different boiling points. Smaller molecules condense high up the tower. Larger molecules condense low down in the tower. Then the fractions are collected.
Recall the names of the main fractions obtained from crude oil
Refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen
Recall a use of refinery gases
Bottled gas
Recall a use of gasoline
Fuel for cars
Recall a use of kerosene
Fuel for aeroplanes
Recall a use of diesel
Fuel for lorries
Recall a use of fuel oil
Fuel for ships
Recall a use of bitumen
Surfacing roads
Describe the trend in boiling points of the main fractions in crude oil
Boiling point increases as the number of carbon atoms (chain length) increase
Describe the trend in viscosity of the main fractions in crude
Viscosity increases as the number of carbon atoms (chain length) increase
Which fraction of crude oil has the lowest boiling point?
Refinery gases
What is meant by the term viscosity?
The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.
Explain why carbon monoxide is dangerous to humans
It is poisonous because it reduces the capacity of the blood to carry oxygen
In car engines, sparks cause the formation of some gases which contribute to acid rain. What are these gases?
Oxides of nitrogen
Why can nitrogen react with oxygen in a car engine?
The temperature is very high
Describe how nitrogen oxides and sulfur dioxide contribute to acid rain
Nitrogen oxides created in hot car engines and sulfur dioxide released when fossil fuels are burned combine with water in the atmosphere to form acidic solutions
Write the chemical equation for sulfur dioxide dissolving in water to form acid rain
SOâ + HâO -> HâSOâ
Describe the problems caused by acid rain
Acid rain damages plant life and life in lakes. It also corrodes limestone and some metals.
Write the chemical equation for the reaction betweem sodium and water
2Na + 2HâO -> 2NaOH + Hâ
State 5 observations when potassium reacts with water
1) fizzing occurs 2) potassium moves around 3) potassium melts 4) lilac flame is seen 5) potassium disappears 6) potassium floats
Complete the equation for the reaction by inserting the state symbols: 2Li(....) + 2HâO(....) -> 2LiOH(...) + Hâ(....)
2Li(s) + 2HâO(l) -> 2LiOH(aq) + Hâ(g)
State 4 observations when sodium reacts with water
1) fizzing occurs 2) sodium moves around 3) sodium melts 4) sodium disappears 5) sodium floats
How should group 1 elements be stored
Under oil
Describe the relative reactivities of the elements in Group 1
The reactivity increases as you go down the group, e.g. Li<Na<K<Rb
State the names of the gases present in air and their % by volume
nitrogen = 78%. oxygen = 21%. argon = 0.96%. carbon dioxide = 0.04%
Name the compound formed when magnesium reacts with oxygen
magnesium oxide
In each of these pairs, which metal is more reactive: 1) sodium and copper. 2) iron and calcium. 3) potassium and aluminium
1) sodium 2) calcium 3) potassium
If 2 similar test tubes contain acid, and a different metal sample is added to each, how might you tell which metal is more reactive?
More bubbles will appear faster in the test tube with the more reactive metal
What is meant by the term atom?
An atom is the smallest part of an element
What is meant by the term molecule?
A molecule is made of a fixed number of two or more atoms covalently bonded together
State the particles that are found within the nucleus of an atom
Protons and neutrons
Explain why atoms are neutral
The numbers of electrons and protons are equal
State the mass of an electron
almost 0
What is meant by the term relative atomic mass, Aáµ£?
The average mass of an atom of an element, relative to 1/12th of the mass of an atom of carbon-12
Explain, in terms of electrons, why isotopes have the same chemical properties
Isotopes have the same number of electrons
What is meant by the term isotope?
Atoms of the same element (same number of protons) but with a different number of neutrons
What is meant by the term mass number?
The number of protons plus the number of neutrons in an atom
What is meant by the term atomic number?
The number of protons in an atom
Elements in the same group in the Periodic Table have the same number of....
electrons in the outer shell
Balance the following equation: WOâ + Hâ -> W + HâO
WOâ + 3Hâ -> W + 3HâO
Balance the equation for the reaction: ___ HCl(aq) + ___ MnOâ(s) -> ___MnClâ(aq) + ___HâO(l) + ___ Clâ(g)
4 HCl(aq) + MnOâ(s) -> MnClâ(aq) + 2HâO(l) + Clâ(g)
Describe the formation of a covalent bond
The sharing of a pair of electrons between two nuclei
Give the definiton of a covalent bond
Strong attraction between a shared pair of electrons and two nuclei
Explain the term covalent bond
Strong attraction between a shared pair of electrons and two nuclei
If a substance has a simple molecular structure, what physical state might it be at room temperature?
Gas or liquid (low melting point)
Explain why nitrogen gas, Nâ, is a gas at room temperature
Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Draw the arrangement of particles in a solid, liquid and gas
What does this represent?
Describe the arrangement, movement and energy of the particles in a solid
Particles are close together and regularly packed. Energy is low. The particles vibrate around a fixed point.
Describe the arrangement and movement of the particles in a liquid
Particles are close together but irregular. The particles are free to move.
Describe the arrangement, movement and energy of the particles in a gas
Particles are far apart and there are no forces between them. Energy is high. The particles move quickly and freely.
Draw 3 particle diagrams to show the arrangement of particles in a solid, liquid and gas. Draw arrows between them and label boiling, condensing and freezing
X=boiling, Y=condensing, Z=freezing
Describe the changes in arrangement, movement and energy of particles when a liquid cools to become a solid
Arrangement becomes more regular. Particles vibrates in a fixed position. Particles lose energy
Describe the changes in arrangement, movement and energy of particles when a liquid turns into a solid
The particles form a regular arrangement, they slow down and lose kinetic energy
State and explain how increasing temperature affects the diffusion of a gas
Gas diffuses quicker because particles have more energy.
Gas particles move at a speed of several hundred metres per second at room temperature. Explain why gases take several minutes to diffuse across a room
Gas particles collide with air particles and move in random directions
State the observation in the reaction between HCl(g) and NHâ(g)
White solid formed
Write a chemical equation for the reaction between hydrogen chloride and ammonia
HCl + NHâ -> NHâCl
What is meant by the term element?
An element is a substance made of only one type of atom
What is meant by the term compound?
A compound is a substance that contains two or more elements chemically joined together
What is meant by the term mixture?
Different substances in the same space, but not chemically combined.
Draw 4 diagrams to show the particles in i) element, ii) compound, iii) mixture, iv) element
These diagrams represent the particles in an element (2), a compound and a mixture, but which is which?
Balance the following equation: WOâ + Hâ -> W + HâO
WOâ + 3Hâ -> W + 3HâO
Balance the equation for the reaction: ___ HCl(aq) + ___ MnOâ(s) -> ___MnClâ(aq) + ___HâO(l) + ___ Clâ(g)
4 HCl(aq) + MnOâ(s) -> MnClâ(aq) + 2HâO(l) + Clâ(g)
What do each of the following state symbols represent: (s), (l), (g), (aq)
(s) - solid. (l) - liquid. (g) - gas. (aq) - aqueous (in solution)
Where are the metals in the Periodic Table? Where are the Non-Metals?
Metals on the left of the Periodic Table. Non-Metals on the top-right, plus Hydrogen.
Are carbon dioxide and sulphur dioxide acidic or basic?
Acidic as carbon and sulphur are non-metals
Write the word and chemical equation for the thermal decompostion of calcium carbonate, CaCOâ
calcium carbonate -> calcium oxide + carbon dioxide CaCOâ -> CaO + COâ
Describe a test to show whether water is pure
If the sample is pure water it will boil at 100â°C
Describe the test for hydrogen gas
Use a lit splint to see if the gas pops
Describe the test for oxygen gas
Use a glowing splint and see if it relights
What is meant by the term exothermic?
A reaction in which heat energy is given out (surroundings get hotter)
What is meant by the term endothermic?
A reaction in which heat energy is taken in (surroundings get colder)