Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Reversing the calculations
20 practice questions
Practice questions
11–20 of 20
Question 11
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 12
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 13
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 14
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 15
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 16
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 17
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.
Question 18
2 marks · Hard
Answer and see the solution →A student wants to completely neutralise 10.0 cm³ of 0.200 mol/dm³ nitric acid with sodium carbonate solution. The balanced equation for the reaction is:
Calculate the minimum volume, in cm³, of 0.100 mol/dm³ sodium carbonate solution required to react fully with the nitric acid.
Question 19
5 marks · Hard
Answer and see the solution →Calcium hydroxide solution reacts with hydrochloric acid according to the following balanced equation:
In a titration, 25.0 cm³ of hydrochloric acid solution of concentration 0.120 mol/dm³ is reacted completely with calcium hydroxide solution.
(a)[1 mark]Calculate the number of moles of HCl present in 25.0 cm³ of solution.
(b)[1 mark]Determine the number of moles of Ca(OH)₂ required to react with this amount of HCl.
(c)[2 marks]Given that the concentration of Ca(OH)₂ is 0.0800 mol/dm³, calculate the volume (in cm³) of Ca(OH)₂ solution that supplies this amount of Ca(OH)₂.
(d)[1 mark]Explain briefly why it is important to use the balanced equation when carrying out these calculations.
Question 20
2 marks · Hard
Answer and see the solution →A solution contains 0.00500 mol of a substance at a concentration of 0.250 mol/dm³.
Calculate the volume of this solution, in cm³, required to provide 0.00500 mol of the substance.