C6 Quick Revision Questions - WordPress.com · C6 Quick Revision Questions C6 for AQA GCSE...
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C6 Quick Revision Questions
C6 for AQA GCSE examination 2018 onwards
H = Higher tier only
All questions apply for combined and separate science
Question 1
• List 3 ways the time of a reaction can be measured.
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• Loss of mass of reactant over time
• Volume of gas produced over time
• Time for a solution to become opaque or coloured
Answer 1 .... of 50
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Question 2
• Name 3 pieces of apparatus used to collect gas in a chemical reaction.
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• upturned measuring cylinder
• Upturned burette
• Gas syringe
Answer 2 .... of 50
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Question 3• Add the following labels to the blanks on the
graph below• Total volume of gas produced
• Reaction has stopped
• Reaction is slower
• Reaction is fastest
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•
Answer 3 .... of 50
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Question 4• What is the time taken for the reaction to
stop?
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• 50 seconds
Answer 4 .... of 50
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Question 5
Sodium thiosulfate and hydrochloric acid are reacted to produce a precipitate of sulfur. The
reaction has finished when the X disappears on the piece of paper underneath the reaction
flask.
Give 2 reasons why this method
may lack accuracy.
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• Different people may interpret the cross disappearing at different times
• The X on the paper could be drawn with different pens making it more/less visible
Answer 5 .... of 50
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Question 6
• What does ‘in excess’ mean in a chemical reaction?
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• There is more than needed of one of the reactants, therefore there will be some of this reactant left over when the reaction has finished.
Answer 6 .... of 50
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Question 7
• What is the limiting reactant?
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• The reactant that is used up by the end of the reaction.
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Question 8
• What is the limiting reactant directly proportional to?
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• The amount of product.
Answer 8 .... of 50
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Question 9
• What happens to the amount of product when the amount of the limiting reactant is
doubled?
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• The amount of product doubles
Answer 9 .... of 50
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Question 10
Ca(s) + 2HCl(aq) CaCl2(aq) + H2(g)
Calcium is the limiting reactant.
If 40g of Calcium react 111g of Calcium Chloride are made.
If 20g of calcium react, how much calcium chloride is made?
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• 55.5g calcium chloride
Answer 10 .... of 50
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Question 11
Ca(s) + 2HCl(aq) CaCl2(aq) + H2(g)
Calcium is the limiting reactant.
If 40g of Calcium react 111g of Calcium Chloride are made.
If 65g of calcium react, how much calcium chloride is made?
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• 166.5g calcium chloride
Answer 11 .... of 50
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Question 12
• What is the rate of reaction?
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• How much product is made in a reaction per second.
Answer 12 .... of 50
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Question 13
• How can the rate of reaction be calculated?
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mean rate of reaction = quantity of reactant used
time taken
or
mean rate of reaction = quantity of product formed
time taken
Answer 13 .... of 50
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Question 14
• How does the rate usually change during a reaction?
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• Reactions are usually faster at the start, then they slow down as the reactants are used up.
Answer 14 .... of 50
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Question 15
• On a volume of gas/time graph, how does the gradient appear when there is a high rate of
reaction?
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• High rate of reaction = Steep (high) gradient
Answer 15 .... of 50
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Question 16
• What is meant by a horizontal line on a volume of gas/time graph
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• The reaction has finished.
Answer 16 .... of 50
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Question 17
• How is the gradient of a line calculated?
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Answer 17 .... of 50
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Question 18
• Calculate the rate of this reaction
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• 52/25 = 2.08cm3/s
Answer 18 .... of 50
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Question 19
• 50cm3 of carbon dioxide gas is made in 20seconds. Calculate the rate of reaction.
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• 2.5cm3/s
Answer 19 .... of 50
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Question 20
• List the factors affecting the rate of a chemical reaction (there’s 5!)
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• Temperature
• Concentration of reactants
• Pressure of reacting gases
• Surface area of solid reactants
• catalyst
Answer 20 .... of 50
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Question 21
• How does temperature affect the rate of reaction?
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• Increase temperature causes an increase in rate of reaction
Answer21 .... of 50
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Question 22
• How does the surface area of solid particle reactants affect the rate of reaction?
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• Small particles have greater surface area therefore a higher rate of reaction
Answer 22 .... of 50
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Question 23• Which line shows the higher concentration of
acid?
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•
Answer 23 .... of 50
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Question 24• Which line shows the higher mass of
Magnesium used in a reaction with hydrochloric acid?
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•
Answer 24 .... of 50
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Question 25
• Which line shows the highest temperature?
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•
Answer 25 .... of 50
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Question 26
• What needs to happen in order for a reaction to take place?
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• Reactant particles need to collide with sufficient energy for a reaction to take place
Answer 26 .... of 50
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Question 27
• What is the name given to the minimum energy needed for a reaction to take place?
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• Activation energy
Answer 27 .... of 50
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Question 28
• Which has the highest rate of reaction, a high or a low concentration of reactant? Use the
collision theory to explain your answer.
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• Higher concentration has a higher rate of reaction
• Higher concentration has more particles in the same volume
• Therefore the particles are more crowded
• Therefore more successful collisions per second (or a higher collision frequency)
Answer 28 .... of 50
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Question 29
• Which has the highest rate of reaction, a high or a low temperature? Use the collision theory
to explain your answer.
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• Higher temperature reactions have a higher rate of reaction
• Higher temperature means the reacting particles have more kinetic energy
• Therefore more particles reacting with the minimum activation energy
• Therefore more successful collisions per second (or a higher collision frequency)
Answer 29 .... of 50
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Question 30
• Which has the highest rate of reaction, a high or a low pressure of gaseous reactant? Use the collision theory to explain your answer.
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• Higher pressure has a higher rate of reaction
• Higher pressure has more particles in the same volume
• Therefore the particles are more crowded
• Therefore more successful collisions per second (or a higher collision frequency)
Answer 30 .... of 50
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Question 31
• What is a catalyst?
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• A substance that speeds up the rate of a chemical reaction but is not used up in the reaction.
Answer 31 .... of 50
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Question 32
• Catalysts are specific, what does this mean?
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• Each catalyst only works for one single reaction. A certain catalyst will not speed up all types of reactions.
Answer 32 .... of 50
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Question 33
• How does a catalyst work?
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• It lowers the activation energy so more of the collisions that take place are successful.
Answer 34 .... of 50
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Question 35• On this energy profile diagram, which
pathway shows a catalyst?
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•
Answer 35 .... of 50
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Question 36
• What is the symbol used for a reversible reaction?
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•
Answer 36 .... of 50
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Question 37
• What is a reversible reaction?
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• reactants form products and products can also form reactants
Answer 37 .... of 50
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Question 38
• How can the direction of reversible reactions be changed?
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By changing conditions such as
• Temperature
• Concentrations of reactants and products
• pressure
Answer 38 .... of 50
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Question 39
• What happens when the forward and the backwards reactions are happening at the
same rate?
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• The reaction is at equilibrium
Answer 39 .... of 50
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Question 40
• How is a closed system achieved?
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• The apparatus prevents products and reactants from escaping
Answer 40 .... of 50
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Question 41
• What is the same when a reaction is in equilibrium?
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• The rates of the forwards and backwards reactions. The concentrations of the reactants and products do not have to be equal.
Answer 41 .... of 50
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Question 42
• What is Le Chatelier’s principle?
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• If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change.
Answer 42 .... of 50
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Question 43
2SO2(g) + O2(g) 2SO3(g)
Using Le Chatelier’s principle, what will happen if the concentration of O2 is decreased?
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• The amount of product (SO3) will decrease in order to produce more O2 and restore the equilibrium.
Answer 43 .... of 50
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Question 44
2SO2(g) + O2(g) 2SO3(g)
Using Le Chatelier’s principle, what can you remove to produce more product?
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• SO3
Answer 44 .... of 50
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Question 45
• Why is the Contact process important in industry?
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• Sulfur trioxide is used to make sulfuric acid which makes fertilisers, paints and plastics.
Answer 45 .... of 50
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Question 46
N2(g) + 3H2(g) 2NH3(g)
The forward reaction is exothermic
How could you change the temperature to increase the yield of the reaction?
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• Decreasing the temperature will increase the forward reaction producing more product.
Answer 46 .... of 50
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Question 47
N2(g) + 3H2(g) 2NH3(g)
The forward reaction is exothermic
Why is a temperature of 450oC used?
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Answer 47 .... of 50
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• Compromise – low temperature is needed to favour exothermic reaction, but a higher
temperature is needed to speed up the rate of reaction
Question 48
N2(g) + 3H2(g) 2NH3(g)
How many moles on the product side?
How many moles on the reactant side?
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Reactants – 4
Products - 2
Answer 48 .... of 50
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Question 49
N2(g) + 3H2(g) 2NH3(g)
How should the pressure be changed to increase the yield?
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• Increase the pressure to favour the product side (which has less moles) and therefore shift the equilibrium to the right.
Answer 49 .... of 50
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Question 50
2SO2(g) + O2(g) 2SO3(g)
What affect you increasing the pressure have on the Contact process?
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• Therefore are fewer number of moles on the products side, therefore increasing the pressure would favour the forward reaction therefore increasing the yield of product
Answer 50 .... of 50
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