Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Changing the concentration of the reactants
19 practice questions
Practice questions
1–10 of 19
Question 1
1 mark · Easy
Answer and see the solution →State what happens to the rate of a reaction if the concentration of a reactant is increased, assuming all other conditions remain the same.
Question 2
3 marks · Easy
Answer and see the solution →A student dilutes 10.0 cm³ of 2.00 mol/dm³ sodium thiosulfate solution by adding water to make a total volume of 50.0 cm³.
(a)[1 mark]State the formula used to calculate the concentration of the diluted solution.
(b)[2 marks]Calculate the concentration of sodium thiosulfate after dilution.
Question 3
2 marks · Easy
Answer and see the solution →In an experiment, 0.27 g of oxygen gas is produced in 45 seconds during the reaction of hydrogen peroxide with manganese(IV) oxide. Calculate the average rate of oxygen production during this time. Give your answer in g/s.
Question 4
2 marks · Easy
Answer and see the solution →A graph plots the rate of a chemical reaction against the concentration of a reactant. The graph is a straight line that passes through the origin. Explain what this tells you about the relationship between the rate of the reaction and the concentration of the reactant.
Question 5
3 marks · Easy
Answer and see the solution →The table gives the results from an experiment measuring the rate of a reaction at two different concentrations of sulfuric acid.
(a)[0 marks]Concentration of acid (mol/dm³) Rate of reaction (g/s) 0.60 0.008 1.20 0.016 (b)[1 mark]Describe the effect of doubling the concentration on the rate of reaction.
(c)[2 marks]Explain why doubling the concentration causes this effect, in terms of particle collisions.
Question 6
1 mark · Easy
Answer and see the solution →A student mixes 16.0 cm³ of 1.50 mol/dm³ hydrochloric acid with water to make 40.0 cm³ of solution. State the concentration of hydrochloric acid after dilution, leaving your answer as a formula or calculation.
Question 7
3 marks · Easy
Answer and see the solution →In an experiment, 0.40 g of carbon dioxide is produced in the first 50 seconds during a reaction between calcium carbonate and hydrochloric acid.
(a)[1 mark]Write down the formula for calculating the average rate of reaction.
(b)[2 marks]Calculate the average rate of reaction in g/s.
Question 8
2 marks · Easy
Answer and see the solution →A student plots a graph showing the initial rate of reaction versus concentration of a reactant. At 0.80 mol/dm³, the rate is 0.011 g/s. Predict the rate if the concentration is increased to 1.60 mol/dm³, assuming the rate is directly proportional to concentration.
Question 9
2 marks · Normal
Answer and see the solution →Describe what happens to the rate of a chemical reaction when the concentration of one of the reactants is increased. Explain your answer.
Question 10
4 marks · Normal
Answer and see the solution →A student is given a bottle of 2.00 mol/dm³ hydrochloric acid. She prepares diluted solutions for a reaction experiment. The total final volume of each solution will be 25.0 cm³.
(a)[2 marks]Calculate the concentration (in mol/dm³) if she mixes 8.0 cm³ of the original acid with 17.0 cm³ of distilled water.
(b)[2 marks]Calculate the concentration (in mol/dm³) if she instead uses 20.0 cm³ of the original acid and 5.0 cm³ of water, making the total volume up to 25.0 cm³.