Chemistry 5070 · O Level · The mole and the Avogadro constant

The mole and the Avogadro constant — practice question

A student examines a solid metal carbonate by means of two separate methods.
(a(i))[1]

Calculate the mass of metal carbonate used.

(a(ii))[1]

Calculate the total change in mass of the contents of the test-tube after heating.

(b)[1]

Explain why the student heats the metal carbonate three times.

(c(i))[1]

Explain why there is a change in mass during heating.

(c(ii))[1]

The $M_r$ of carbon dioxide is $44$. Use your result from (a)(ii) to work out the amount of carbon dioxide produced in the reaction.

(c(iii))[1]

Use the equation $\text{MCO}_3\text{(s)} \rightarrow \text{MO(s)} + \text{CO}_2\text{(g)}$ to calculate the number of moles of metal carbonate used in the experiment.

(c(iv))[1]

Use your answers to (a)(i) and (c)(iii) to calculate the mass of one mole of the metal carbonate.

(c(v))[2]

Calculate the $A_r$ of metal $M$. Use $[A_r: \text{C},12; \text{O},16]$

(d(i))[1]

Name the apparatus used to collect the carbon dioxide.

(d(ii))[1]

State the volume of carbon dioxide collected.

(d(iii))[1]

Calculate the number of moles of carbon dioxide collected. [$1$ mole of any gas at room temperature and pressure takes up $24\,\text{dm}^3$]

(d(iv))[1]

Suggest a reason why method $2$ is less accurate than method $1$.

(d(v))[2]

Identify a hazard in method $2$ and suggest a safety precaution to reduce the risk associated with this hazard.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: The mass of carbonate is 4.20 g

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