Learn Extracted exam questions A-Level Chemistry 9701 Chemistry June 2025 Question Paper 34
9701 Chemistry June 2025 Question Paper 34
Source PDF on the left, extracted YAML on the right. Compare numbering, marks, options and text.
Iron is an element that is essential in the human diet. Some people need to take iron supplement tablets to ensure an adequate intake of iron.
You will investigate the mass of iron in an iron supplement tablet by titrating a solution with potassium manganate(VII).
\textbf{FB 1} is an aqueous solution of iron supplement tablets made by dissolving 14 tablets in $1.00\text{dm}^3$ of solution. The iron in each tablet is iron(II) sulfate, $\text{FeSO}_4 \cdot 7\text{H}_2\text{O}$. \textbf{FB 2} is $0.0100\text{mol}\,\text{dm}^{-3}$ acidified aqueous potassium manganate(VII), $\text{KMnO}_4$. \textbf{FB 3} is dilute sulfuric acid, $\text{H}_2\text{SO}_4$.
\textbf{Method}
\begin{itemize} \item Fill a burette with \textbf{FB 2}. \item Pipette $25.0\text{cm}^3$ of \textbf{FB 1} into a conical flask. \item Use the $25\text{cm}^3$ measuring cylinder to add $10.0\text{cm}^3$ of \textbf{FB 3} to the conical flask. \item Perform a rough titration and record your burette readings in the space below. \end{itemize}
The rough titre is \underline{\hspace{1.5em}} $\text{cm}^3$.
\begin{itemize} \item Carry out as many accurate titrations as you think necessary to obtain consistent results. \item Make sure any recorded results show the precision of your practical work. \item Record, in a suitable form in the space below, all your burette readings and the volume of \textbf{FB 2} added in each accurate titration. \end{itemize}
\textbf{Rinse the burette with distilled water and leave to drain while you continue Question 1.}
\textbf{Results}
From your accurate titration results, calculate a suitable mean value to use in your calculations. Show clearly how you obtain the mean value.
$25.0 \text{ cm}^3$ of \textbf{FB 1} required \hrulefill $\text{ cm}^3$ of \textbf{FB 2}.
Calculations
Give your answers to \textbf{(c)(ii)}, \textbf{(c)(iii)} and \textbf{(c)(iv)} to an appropriate number of significant figures.
Calculate the amount, in mol, of manganate(VII) ions in the volume of \textbf{FB 2} in \textbf{(b)}.
amount of $\text{MnO}_4^-$ = \hrulefill mol
Use your answer to \textbf{(c)(ii)} and the equations at the start of the question to calculate the concentration, in $\text{mol}\,\text{dm}^{-3}$, of iron(II) ions in \textbf{FB 1}.
concentration of $\text{Fe}^{2+}$ = \hrulefill $\text{mol}\,\text{dm}^{-3}$
Use your answer to \textbf{(c)(iii)} to calculate the concentration, in $\text{g}\,\text{dm}^{-3}$, of iron(II) ions in \textbf{FB 1}.
concentration of $\text{Fe}^{2+}$ = \hrulefill $\text{g}\,\text{dm}^{-3}$
The manufacturer of the iron supplement tablets used to make \textbf{FB 1} claims that each tablet contains a minimum of $150 \text{ mg}$ of $\text{Fe}^{2+}$.
Use your answer to \textbf{(c)(iv)} and the information given about \textbf{FB 1} to determine whether this claim is correct. Show your working.
A student used all the \textbf{FB 3} and suggests that dilute hydrochloric acid would be a suitable replacement. Suggest whether the student is correct or not. Explain your answer.
The reaction between an acid and an alkali is exothermic. You will carry out a neutralisation experiment to determine the enthalpy change involved.
You will mix different volumes of an acid with a fixed volume of an alkali and measure the temperature rises that occur.
FB 4 is aqueous sodium hydroxide, NaOH. FB 5 is $2.00 \text{ mol dm}^{-3}$ hydrochloric acid, HCl.
\textbf{Method}
\begin{itemize} \item Use the thermometer to measure the initial temperature of FB 4. Record this initial temperature in the space for results. \item Support the cup in the $250 \text{ cm}^3$ beaker. \item Fill one burette with FB 5. Label the burette FB 5. \item Fill the other burette with distilled water. \end{itemize}
Experiment 1
\begin{itemize} \item Use the $10 \text{ cm}^3$ pipette to transfer $10.0 \text{ cm}^3$ of FB 4 into the cup. \item Add $9.00 \text{ cm}^3$ of distilled water from the burette to the same cup. \item Add $1.00 \text{ cm}^3$ of FB 5 from the other burette to the same cup. \item Stir the mixture and use the thermometer to measure the maximum temperature. If necessary, tilt the cup so that the solution covers the bulb of the thermometer. \item Record the maximum temperature in Table 2.1. \item Empty, rinse and dry the cup ready for use in further experiments. \end{itemize}
\textbf{Further experiments}
Repeat this method for Experiments 2–5, using $10.0 \text{ cm}^3$ of FB 4 and the volumes of water and FB 5 shown in Table 2.1. In each case, measure and record the maximum temperature.
Carry out \textbf{two} further experiments, Experiments 6 and 7, which will enable you to determine more precisely the volume of FB 5 that gives the largest maximum temperature. Record your measurements in Table 2.1.
\textbf{Results}
initial temperature of FB 4 = \hrulefill $^\circ\text{C}$
Table 2.1
\begin{tabular}{|c|c|c|c|} \hline experiment & volume of water / $\text{cm}^3$ & volume of FB 5 / $\text{cm}^3$ & maximum temperature / $^\circ\text{C}$ \ \hline 1 & 9.00 & 1.00 & \ \hline 2 & 7.00 & 3.00 & \ \hline 3 & 5.00 & 5.00 & \ \hline 4 & 3.00 & 7.00 & \ \hline 5 & 1.00 & 9.00 & \ \hline 6 & & & \ \hline 7 & & & \ \hline \end{tabular}
Plot a graph of the maximum temperature ($y$-axis) against the volume of FB 5 ($x$-axis) on the grid. The scale on the $y$-axis should be suitable for temperature readings to be 2°C above the largest maximum temperature.
Label any points you consider to be anomalous.
Draw \textbf{two} lines of best fit, the first for the increase in maximum temperature and the second for after the largest maximum temperature has been reached. Extrapolate both lines so that they intersect.
\begin{tabular}{|c|c|c|c|c|c|c|} \hline I & & II & & III & & IV \ \hline \end{tabular}
Use the intersection on your graph in (b)(i) to determine the volume of FB 5 required to neutralise $10.0\text{ cm}^3$ of FB 4.
volume of FB 5 = \hrulefill $\text{cm}^3$
Calculations
Calculate the amount, in mol, of hydrochloric acid in the volume of FB 5 in (b)(ii).
(If you were unable to determine an answer to (b)(ii), use $5.10\text{ cm}^3$ as the volume of FB 5. This may \textbf{not} be the correct answer.)
amount of $\text{HCl}$ = \hrulefill mol
Deduce the amount, in mol, of sodium hydroxide in $10.0\text{ cm}^3$ of FB 4.
amount of $\text{NaOH}$ = \hrulefill mol
Calculate the energy change, in J, when the amounts of reagents in (c)(i) neutralise each other. Show your working.
energy change = \hrulefill J
Use your answer to (c)(ii) to calculate the enthalpy change, in $\text{kJ}\,\text{mol}^{-1}$, when one mole of FB 4 is neutralised by one mole of FB 5.
enthalpy change = \hrulefill \hrulefill $\text{kJ}\,\text{mol}^{-1}$ \hspace*{8.5em} sign \hspace*{3em} value
\textbf{Qualitative analysis}
For each test you should record all your observations in the spaces provided.
Examples of observations include: \begin{itemize} \item colour changes seen \item the formation of any precipitate and its solubility (where appropriate) in an excess of the reagent added \item the formation of any gas and its identification (where appropriate) by a suitable test. \end{itemize}
You should record clearly at what stage in a test an observation is made.
Where no change is observed, you should write ‘no change’.
Where reagents are selected for use in a test, the name or correct formula of the element or compound must be given.
If any solution is warmed, a boiling tube must be used. If a solid is heated, a hard-glass test-tube must be used.
Rinse and reuse test-tubes and boiling tubes where possible.
No additional tests should be attempted.
FB 6, FB 7 and FB 8 are aqueous solutions of different compounds that each contain at least one oxygen atom.
Carry out the following tests and record your observations in Table 3.1. Three of the tests have been done for you. Use a 1 cm depth of solution in a test-tube for each test.
\textbf{Table 3.1}
\begin{tabular}{|p{3cm}|c|c|c|} \hline \multicolumn{1}{|c|}{\textit{test}} & \multicolumn{3}{c|}{\textit{observations}} \ \cline{2-4} & \textbf{FB 6} & \textbf{FB 7} & \textbf{FB 8} \ \hline \textbf{Test 1} \newline Add a small spatula measure of manganese(IV) oxide. & No change. & No change. & \ \hline \textbf{Test 2} \newline Add a 1 cm length of magnesium. & & & No change. \ \hline \textbf{Test 3} \newline Add a few drops of aqueous iron(II) sulfate. & & & \ \hline \end{tabular}
\hfill
Use your observations in Table 3.1 to suggest a possible formula for each of FB 6, FB 7 and FB 8.
FB 6 \hrulefill FB 7 \hrulefill FB 8 \hrulefill
FB 9 contains two anions and two cations, three of which are listed in the Qualitative analysis notes.
To a small spatula measure of FB 9 in a test-tube, add a 2cm depth of dilute nitric acid. Record your observations.
Keep the resulting solution for the test in (b)(ii).
To the solution from (b)(i), add a few drops of aqueous silver nitrate. Then add excess aqueous ammonia. Record your observations.
Make an aqueous solution of FB 9 by adding a 5 cm depth of distilled water to a spatula measure of FB 9 in a test-tube. Carry out the following tests on the aqueous solution of FB 9 and record your observations in Table 3.2.
Table 3.2
\begin{tabular}{|p{6cm}|p{6cm}|} \hline \multicolumn{1}{|c|}{test} & \multicolumn{1}{|c|}{observations} \ \hline \textbf{Test 1} \newline To a 1 cm depth in a boiling tube, add aqueous sodium hydroxide, \newline then \hrulefill \newline warm. & \ \hline \textbf{Test 2} \newline To a 1 cm depth in a test-tube, add a few drops of dilute hydrochloric acid, \newline then add a few drops of aqueous chlorine. \newline \textbf{Empty and rinse the test-tube with water immediately after use.} & \ \hline \end{tabular}
Use your observations in \textbf{(b)(i)}, \textbf{(b)(ii)} and Table 3.2 to deduce the formulae of the cations and anions in FB 9. If you are unable to identify an ion, write ‘unknown’.
cations \underline{\hspace{1.5em}} and \underline{\hspace{1.5em}}
anions \underline{\hspace{1.5em}} and \underline{\hspace{1.5em}}
Write an ionic equation for the reaction in \textbf{(b)(ii)}. Include state symbols.