Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Reversing the calculations
20 practice questions
Practice questions
1–9 of 9 · Normal
Question 1
2 marks · Normal
Answer and see the solution →Sodium carbonate solution reacts with hydrochloric acid:
Calculate the volume (in cm³) of 0.200 mol/dm³ sodium carbonate solution required to completely react with 30.0 cm³ of 0.400 mol/dm³ hydrochloric acid.
Question 2
4 marks · Normal
Answer and see the solution →A laboratory technician needs to prepare a solution containing 0.00250 mol of silver nitrate (AgNO₃) and wants the final concentration to be 0.0500 mol/dm³.
(a)[1 mark]Write the equation used to calculate the required volume (in dm³) of solution.
(b)[2 marks]Calculate the volume of solution (in dm³) required to obtain the stated concentration.
(c)[1 mark]Convert your answer to part (b) into cm³.
Question 3
3 marks · Normal
Answer and see the solution →Potassium hydroxide solution reacts with sulfuric acid as follows:
Calculate the minimum volume (in cm³) of 0.150 mol/dm³ sulfuric acid required to completely react with 25.0 cm³ of 0.300 mol/dm³ potassium hydroxide solution.
Question 4
3 marks · Normal
Answer and see the solution →Explain, using a calculation, how you would work out the volume of 0.250 mol/dm³ potassium hydroxide solution needed to neutralise 10.0 cm³ of 0.500 mol/dm³ sulfuric acid, given the following equation:
Show your reasoning and working clearly.
Question 5
2 marks · Normal
Answer and see the solution →Ammonia reacts with hydrochloric acid according to the equation:
Calculate the required volume (in cm³) of 0.250 mol/dm³ ammonia solution needed to react completely with 15.0 cm³ of 0.200 mol/dm³ hydrochloric acid solution.
Question 6
4 marks · Normal
Answer and see the solution →A student has 0.00800 mol of citric acid dissolved in water to make a solution. She needs to prepare the solution so that its concentration is exactly 0.200 mol/dm³.
(a)[1 mark]Write the rearranged formula used to calculate the volume required in dm³, in terms of moles and concentration.
(b)[2 marks]Calculate the required volume of solution, in dm³, to make the desired concentration.
(c)[1 mark]Convert your answer from (b) to cm³.
Question 7
3 marks · Normal
Answer and see the solution →Explain, step by step, how you would calculate the required volume of one solution needed to react completely with a known amount of another reactant, using their concentrations and the chemical equation. Include the reason for each step.
Question 8
4 marks · Normal
Answer and see the solution →The table shows several solutions, each with a different number of moles and concentration.
Solution data Solution Moles (mol) Concentration (mol/dm³) A 0.00250 0.100 B 0.00800 0.200 C 0.00450 0.300 D 0.00180 0.0600 For each solution in the table, calculate and enter the volume (in cm³) needed to contain the given moles at the given concentration. Show your working for Solution A.
Question 9
3 marks · Normal
Answer and see the solution →Citric acid reacts with sodium hydroxide as follows:
Calculate the volume, in cm³, of 0.300 mol/dm³ sodium hydroxide solution required to completely neutralise 20.0 cm³ of 0.200 mol/dm³ citric acid solution.