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