Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Changing the concentration of the reactants
19 practice questions
Practice questions
1–3 of 3 · Hard
Question 1
2 marks · Hard
Answer and see the solution →A student investigates the reaction between calcium carbonate and hydrochloric acid. State, with a reason, what happens to the rate of reaction if the concentration of hydrochloric acid is reduced to a third, assuming all other conditions remain the same.
Question 2
5 marks · Hard
Answer and see the solution →A student prepares dilute hydrochloric acid for a reaction by adding water to a known volume of 2.50 mol/dm³ hydrochloric acid. She then uses the solution to react with marble chips.
(a)[2 marks]She mixes 10.0 cm³ of 2.50 mol/dm³ acid with 30.0 cm³ of water to make 40.0 cm³ of solution. Calculate the concentration, in mol/dm³, of the hydrochloric acid after dilution.
(b)[2 marks]She repeats the process, using 25.0 cm³ of 2.50 mol/dm³ acid topped up with water to 40.0 cm³. Calculate the new concentration, in mol/dm³, after dilution.
(c)[1 mark]State the formula used to calculate the final concentration when diluting a solution.
Question 3
2 marks · Hard
Answer and see the solution →An experiment produced 0.46 g of carbon dioxide in the first 20 seconds during the reaction of marble chips with dilute hydrochloric acid. Calculate the average rate of carbon dioxide production, giving your answer in g/s. Show your working.