Amount of Substance & Gas Volume Practice Questions

Which container holds the greatest number of gas molecules?

Tick one box.

• Container A
• Container B
• Container C
• All three containers hold the same number of molecules

Calculate the mass of chlorine gas in container C.

Relative formula mass ($M_\mathrm{r}$): $\mathrm{Cl_2} = 71$

Mass of chlorine = .................... g

The hydrogen in container A reacts with excess chlorine.

The equation for the reaction is:

$$\mathrm{H_2(g)} + \mathrm{Cl_2(g)} \rightarrow 2\mathrm{HCl(g)}$$

Calculate the volume of hydrogen chloride produced at rtp.

Volume of hydrogen chloride = .................... dm$^3$

Sulfur dioxide is produced when sulfur is burned in air.

Calculate the volume of $6.4\ \mathrm{g}$ of sulfur dioxide at room temperature and pressure.

Relative formula mass ($M_\mathrm{r}$): $\mathrm{SO_2} = 64$

The volume of 1 mole of any gas at room temperature and pressure is 24 dm$^3$.

Volume of sulfur dioxide = .................... dm$^3$

Rearrange the equation to make the number of moles the subject.

Calculate the number of moles of hydrogen collected by the student.

Number of moles = ....................

Calculate the mass of hydrogen collected.

Relative formula mass ($M_\mathrm{r}$): $\mathrm{H_2} = 2$

Mass of hydrogen = .................... g

Zinc reacts with dilute sulfuric acid to produce hydrogen gas.

The equation for the reaction is:

$$\mathrm{Zn(s)} + \mathrm{H_2SO_4(aq)} \rightarrow \mathrm{ZnSO_4(aq)} + \mathrm{H_2(g)}$$

$3.25\ \mathrm{g}$ of zinc reacts completely with excess dilute sulfuric acid.

Calculate the volume of hydrogen produced at room temperature and pressure.

Relative atomic mass ($A_\mathrm{r}$): Zn = 65

The volume of 1 mole of any gas at room temperature and pressure is 24 dm$^3$.

Volume of hydrogen = .................... dm$^3$

Complete the table.

Assume that all of the nitrogen and hydrogen react in each experiment.

Explain why $20\ \mathrm{cm^3}$ of nitrogen reacts with exactly three times its own volume of hydrogen.

An airbag must be filled with $72\ \mathrm{dm^3}$ of nitrogen at room temperature and pressure.

Calculate the mass of sodium azide needed.

Mass of sodium azide = .................... g

A smaller airbag in the same car contains $1.30\ \mathrm{g}$ of sodium azide.

Calculate the volume of nitrogen, in dm$^3$, produced at room temperature and pressure when all of this sodium azide decomposes.

Volume of nitrogen = .................... dm$^3$

Calculate the relative formula mass ($M_\mathrm{r}$) of gas X.

$M_\mathrm{r}$ of gas X = ....................

Use your answer to part (a) to identify gas X.

Tick one box.

• Methane, $\mathrm{CH_4}$
• Ammonia, $\mathrm{NH_3}$
• Carbon dioxide, $\mathrm{CO_2}$
• Sulfur dioxide, $\mathrm{SO_2}$

Gas X can be made in the laboratory by heating calcium carbonate.

The equation for the reaction is:

$$\mathrm{CaCO_3(s)} \rightarrow \mathrm{CaO(s)} + \mathrm{CO_2(g)}$$

Calculate the mass of calcium carbonate that must be heated to produce $600\ \mathrm{cm^3}$ of gas X at room temperature and pressure.

Relative formula mass ($M_\mathrm{r}$): $\mathrm{CaCO_3} = 100$

Mass of calcium carbonate = .................... g