Concentration of Solutions Practice Questions

A student dissolves $0.0600$ mol of potassium bromide in water.

The volume of the solution made is $400\ \mathrm{cm^3}$.

Calculate the concentration of the potassium bromide solution in $\mathrm{mol/dm^3}$.

[2 marks]

Concentration = ...................................... $\mathrm{mol/dm^3}$

The technician needs $500\ \mathrm{cm^3}$ of sodium carbonate solution with a concentration of $0.125\ \mathrm{mol/dm^3}$.

Calculate the mass of sodium carbonate ($\mathrm{Na_2CO_3}$) the technician should dissolve.

Relative atomic masses ($A_r$): C = 12 O = 16 Na = 23

[3 marks]

Mass = ...................................... g

A sample of sea water contains dissolved sodium chloride ($\mathrm{NaCl}$) at a concentration of $0.470\ \mathrm{mol/dm^3}$.

Calculate the mass of sodium chloride dissolved in $2.50\ \mathrm{dm^3}$ of this sea water.

Relative formula mass ($M_r$): $\mathrm{NaCl}$ = 58.5

Give your answer to 3 significant figures.

[3 marks]

Mass = ...................................... g

A student has $50.0\ \mathrm{cm^3}$ of copper(II) sulfate solution of concentration $0.400\ \mathrm{mol/dm^3}$.

The student pours all of this solution into a measuring cylinder and adds water until the total volume of the solution is $250\ \mathrm{cm^3}$.

Calculate the concentration, in $\mathrm{mol/dm^3}$, of the diluted copper(II) sulfate solution.

[3 marks]

Concentration = ...................................... $\mathrm{mol/dm^3}$

The table shows the student's results.

Solution	Volume in $\mathrm{cm^3}$	Concentration in $\mathrm{mol/dm^3}$
calcium hydroxide	$25.0$	$0.0500$
nitric acid	$22.4$	not known

Calculate the concentration of the nitric acid in $\mathrm{mol/dm^3}$.

Give your answer to 3 significant figures.

[4 marks]

Concentration = ...................................... $\mathrm{mol/dm^3}$

$21.30\ \mathrm{cm^3}$ of the hydrochloric acid was needed to react completely with the $25.0\ \mathrm{cm^3}$ of sodium carbonate solution.

Calculate the concentration of the hydrochloric acid in $\mathrm{g/dm^3}$.

Relative formula mass ($M_r$): $\mathrm{HCl}$ = 36.5

[4 marks]

Concentration = ...................................... $\mathrm{g/dm^3}$

A bottle of sodium hydroxide solution is labelled:

sodium hydroxide solution, $8.00\ \mathrm{g/dm^3}$

$25.0\ \mathrm{cm^3}$ of this sodium hydroxide solution was neutralised by exactly $20.0\ \mathrm{cm^3}$ of dilute sulfuric acid.

The equation for the reaction is:

$$\mathrm{H_2SO_4} + 2\,\mathrm{NaOH} \rightarrow \mathrm{Na_2SO_4} + 2\,\mathrm{H_2O}$$

Calculate the concentration of the sulfuric acid in $\mathrm{mol/dm^3}$.

Relative formula mass ($M_r$): $\mathrm{NaOH}$ = 40

[4 marks]

Concentration = ...................................... $\mathrm{mol/dm^3}$