Chemistry 9701 · AS & A Level · Atoms, molecules and stoichiometry

Atoms, molecules and stoichiometry — practice question

A neutralisation reaction takes place when $\text{NaOH(aq)}$ is added to $\text{H}_2\text{SO}_4\text{(aq)}$.\n\nEquation 1: $2\text{NaOH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{Na}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O(l)}$
(a)[2]

Define what is meant by the enthalpy change of neutralisation, $\Delta H_{\text{neut}}$.

(b(i))[1]

Use equation 1 to work out the amount, in mol, of $\text{H}_2\text{SO}_4\text{(aq)}$ neutralised in the experiment.

(b(ii))[3]

Calculate the theoretical maximum temperature of the mixture in this experiment. Assume that the enthalpy change of neutralisation, $\Delta H_{\text{neut}}$, of $\text{NaOH(aq)}$ and $\text{H}_2\text{SO}_4\text{(aq)}$ is $-57.1\,\text{kJ mol}^{-1}$, full dissociation of $\text{H}_2\text{SO}_4\text{(aq)}$ occurs, the specific heat capacity of the final solution is $4.18\,\text{J g}^{-1}\text{K}^{-1}$, $1.00\,\text{cm}^3$ of the final solution has a mass of $1.00\,\text{g}$, there is no heat loss to the surroundings, and the experiment takes place at constant pressure. Show your working.

(c(i))[1]

Complete the equation for the reaction: $\text{CH}_3\text{COOH} + \text{NaOH} \rightarrow \;\;\;\;\;\;\;\;$

(c(ii))[1]

Suggest why the value of $\Delta H_{\text{neut}}$ for the weak acid, $\text{CH}_3\text{COOH}$, reacting with $\text{NaOH}$ is different from the value found using the strong acid, $\text{HCl}$. Assume the results are obtained under the same conditions.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: enthalpy change when 1 mole of water is formed

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