2023 Cambridge IAS-Level Chemistry (9701) Practice Paper with Answers

10 cm\(^3\) of a gaseous hydrocarbon was reacted with 50 cm\(^3\) of oxygen (an excess) by combustion. After cooling to room temperature, the total volume of gas remaining was 40 cm\(^3\). Passing this gas mixture through aqueous sodium hydroxide caused the volume of the gas to decrease to 10 cm\(^3\). What is the molecular formula of the hydrocarbon?

A sample of 4.34 g of a hydrated metal sulfate, \(M_x(SO_4)_y \cdot nH_2O\), is heated until all the water of crystallisation is lost, leaving a residue of anhydrous metal sulfate of mass 2.54 g. In a separate experiment, 0.010 mol of this anhydrous metal sulfate is found to contain 0.020 mol of metal ions, \(M^{z+}\). What is the formula of the hydrated metal sulfate? (The relative formula mass of the anhydrous metal sulfate is 254.)

The standard enthalpy changes of combustion of carbon, hydrogen, and methanoic acid are given in the table:

- \(C(s)\): \(-393.5 \text{ kJ mol}^{-1}\)
- \(H_2(g)\): \(-285.8 \text{ kJ mol}^{-1}\)
- \(HCOOH(l)\): \(-263.0 \text{ kJ mol}^{-1}\)

The standard enthalpy change of formation of liquid methanoic acid is represented by the equation:

\(C(s) + H_2(g) + O_2(g) \rightarrow HCOOH(l)\)

What is the standard enthalpy change of formation, \(\Delta H^\theta_f\), of liquid methanoic acid?

The enthalpy change of solution of anhydrous magnesium sulfate, \(MgSO_4(s)\), is \(-91.2 \text{ kJ mol}^{-1}\). The enthalpy change of solution of hydrated magnesium sulfate, \(MgSO_4 \cdot 7H_2O(s)\), is \(+13.8 \text{ kJ mol}^{-1}\).

The hydration of anhydrous magnesium sulfate is represented by:

\(MgSO_4(s) + 7H_2O(l) \rightarrow MgSO_4 \cdot 7H_2O(s)\)

What is the standard enthalpy change of hydration, \(\Delta H^\theta_{\text{hyd}}\), of anhydrous magnesium sulfate?

An unsymmetrical alkene \(X\) has the molecular formula \(C_5H_{10}\). When \(X\) reacts with cold, concentrated sulfuric acid, followed by warming with water, a mixture of two isomeric alcohols, \(Y\) and \(Z\), is formed. Alcohol \(Y\) is a secondary alcohol that can be oxidised to a ketone. Alcohol \(Z\) is a tertiary alcohol that is resistant to oxidation by acidified potassium dichromate(VI). What is the IUPAC name of the alkene \(X\)?

A hydrocarbon \(W\) with molecular formula \(C_6H_{10}\) is reacted with hot, concentrated, acidified potassium manganate(VII). The only organic product formed is a single compound \(V\) with molecular formula \(C_6H_{10}O_2\). Compound \(V\) reacts with 2,4-dinitrophenylhydrazine (2,4-DNPH) reagent to form an orange precipitate, but does not react with Tollens' reagent. What is the IUPAC name of the hydrocarbon \(W\)?

The successive ionisation energies, in kJ mol\(^{-1}\), for an element \(T\) in Period 3 of the Periodic Table are shown below:

- 1st: 578
- 2nd: 1817
- 3rd: 2745
- 4th: 11578
- 5th: 14831
- 6th: 18378

Which statement about element \(T\) or its compounds is correct?

Which statement correctly explains why the first ionisation energy of sulfur is lower than that of phosphorus?

A mixture of 0.10 mol of anhydrous magnesium nitrate, \( \text{Mg(NO}_3\text{)}_2 \), and 0.10 mol of anhydrous magnesium carbonate, \( \text{MgCO}_3 \), is heated strongly until both compounds have completely decomposed.

The gaseous products are collected and allowed to cool to room temperature and pressure (r.t.p.).

What is the total volume of gas collected at r.t.p.?

(Assume all gaseous products behave ideally. \( \text{NO}_2 \) remains gaseous at r.t.p.)

An excess of solid zinc powder is added to \( 50.0 \text{ cm}^3 \) of \( 0.200 \text{ mol dm}^{-3} \) silver nitrate solution.

\( \text{Zn}(s) + 2\text{Ag}^+(aq) \rightarrow \text{Zn}^{2+}(aq) + 2\text{Ag}(s) \)

The precipitated silver is filtered, dried, and weighed. The actual mass of silver obtained is \( 0.972 \text{ g} \).

What is the percentage yield of silver?

[\( A_r \text{: Ag} = 107.9 \)]

Use the standard enthalpies of combustion below to calculate the standard enthalpy of formation of liquid methanol, \( \text{CH}_3\text{OH}(l) \).

\( \Delta H_c^\ominus [\text{C}(s)] = -393.5 \text{ kJ mol}^{-1} \)
\( \Delta H_c^\ominus [\text{H}_2(g)] = -285.8 \text{ kJ mol}^{-1} \)
\( \Delta H_c^\ominus [\text{CH}_3\text{OH}(l)] = -726.0 \text{ kJ mol}^{-1} \)

What is the standard enthalpy of formation of liquid methanol in \( \text{kJ mol}^{-1} \)?

The standard enthalpy change for the hydrogenation of propene is given:

\( \text{CH}_2\text{=CHCH}_3(g) + \text{H}_2(g) \rightarrow \text{CH}_3\text{CH}_2\text{CH}_3(g) \quad \Delta H^\ominus = -124 \text{ kJ mol}^{-1} \)

Using the average bond energies in the table below, what is the bond energy of the \( \text{C=C} \) double bond?

- \( \text{C-C} \): 347 kJ mol-1
- \( \text{C-H} \): 413 kJ mol-1
- \( \text{H-H} \): 436 kJ mol-1

When 2-methylbut-2-ene reacts with cold, concentrated sulfuric acid, followed by warming with water, a major organic product is formed.

Which intermediate carbocation is formed in the rate-determining step to yield this major product?

An unknown alkene, X, is reacted with hot, concentrated, acidified potassium manganate(VII), \( \text{KMnO}_4 \).

The only organic products obtained are propanone, \( \text{CH}_3\text{COCH}_3 \), and propanoic acid, \( \text{CH}_3\text{CH}_2\text{CO}_2\text{H} \).

What is the IUPAC name of alkene X?

The table below shows the first six successive ionisation energies, in \( \text{kJ mol}^{-1} \), of an element Y in Period 3 of the Periodic Table.

| 1st | 2nd | 3rd | 4th | 5th | 6th |
|---|---|---|---|---|---|
| 578 | 1817 | 2745 | 11578 | 14831 | 18378 |

Which statement about element Y is correct?

The first ionisation energies of the elements in Period 3 generally increase from left to right. However, there are exceptions (dips) in this trend.

Between which two elements in Period 3 is there a decrease in first ionisation energy due to spin-pair repulsion in a p-orbital?

A \(10\text{ cm}^3\) sample of gaseous propane, \(\text{C}_3\text{H}_8\), was mixed with \(70\text{ cm}^3\) of oxygen (an excess) and exploded in a sealed vessel. The vessel was cooled back to room temperature and pressure, and the remaining gas mixture was then shaken with excess aqueous sodium hydroxide. What is the total reduction in the volume of gas from the start of the experiment to the end of the procedure? (All gas volumes are measured at room temperature and pressure.)

A sample of \(5.72\text{ g}\) of hydrated sodium carbonate, \(\text{Na}_2\text{CO}_3 \cdot x\text{H}_2\text{O}\), is dissolved in distilled water and made up to \(250.0\text{ cm}^3\) of solution in a volumetric flask. A \(25.0\text{ cm}^3\) portion of this solution is titrated against \(0.200\text{ mol dm}^{-3}\) hydrochloric acid, \(\text{HCl}\). It requires \(20.0\text{ cm}^3\) of the acid for complete neutralisation: \(\text{Na}_2\text{CO}_3(\text{aq}) + 2\text{HCl}(\text{aq}) \rightarrow 2\text{NaCl}(\text{aq}) + \text{CO}_2(\text{g}) + \text{H}_2\text{O}(\text{l})\). What is the value of \(x\)? (Relative atomic masses: \(\text{H}=1.0\), \(\text{C}=12.0\), \(\text{O}=16.0\), \(\text{Na}=23.0\))

The standard enthalpy change of combustion of iron, \(\text{Fe(s)}\), to form iron(III) oxide, \(\text{Fe}_2\text{O}_3(\text{s})\), is \(-411\text{ kJ mol}^{-1}\). The standard enthalpy change of combustion of carbon (graphite) to form carbon dioxide, \(\text{CO}_2(\text{g})\), is \(-394\text{ kJ mol}^{-1}\). What is the enthalpy change for the reduction of iron(III) oxide by carbon according to the equation shown below? \(2\text{Fe}_2\text{O}_3(\text{s}) + 3\text{C(s)} \rightarrow 4\text{Fe(s)} + 3\text{CO}_2(\text{g})\)

The standard enthalpy changes of combustion, \(\Delta H_c^\ominus\), at 298 K, for three substances are given in the table below:

| Substance | \(\Delta H_c^\ominus / \text{kJ mol}^{-1}\) |
|---|---|
| \(\text{C(s, graphite)}\) | \(-394\) |
| \(\text{H}_2(\text{g})\) | \(-286\) |
| \(\text{CH}_3\text{CH}_2\text{COOH(l)}\) | \(-1527\) |

What is the standard enthalpy change of formation, \(\Delta H_f^\ominus\), of propanoic acid, \(\text{CH}_3\text{CH}_2\text{COOH(l)}\)?

An alkene, \(X\), reacts with hot, concentrated, acidified \(\text{KMnO}_4\) to give propanone as the only organic product. Which statement about \(X\) and its reactions is correct?

When 2-methylbut-2-ene reacts with hydrogen bromide, \(\text{HBr}\), two bromoalkanes are formed. One is the major product and the other is the minor product. Which option correctly describes the first step of the electrophilic addition mechanism and identifies the major organic product?

An element, \(Y\), in Period 3 of the Periodic Table has the following first six successive ionisation energies (in \(\text{kJ mol}^{-1}\)):

- 1st: 1012
- 2nd: 1903
- 3rd: 2912
- 4th: 4957
- 5th: 6274
- 6th: 21269

Which statement about element \(Y\) is correct?

The first ionisation energies of five consecutive elements in Period 3, in order of increasing atomic number, are given below:

- Element 1: 738 \(\text{kJ mol}^{-1}\)
- Element 2: 578 \(\text{kJ mol}^{-1}\)
- Element 3: 786 \(\text{kJ mol}^{-1}\)
- Element 4: 1012 \(\text{kJ mol}^{-1}\)
- Element 5: 1000 \(\text{kJ mol}^{-1}\)

Which statement about these elements is correct?

A sample of 0.200 mol of an anhydrous metal nitrate, \( \text{M(NO}_3)_2 \), is heated strongly until it decomposes completely.\
\
\( 2\text{M(NO}_3)_2(\text{s}) \rightarrow 2\text{MO}(\text{s}) + 4\text{NO}_2(\text{g}) + \text{O}_2(\text{g}) \)\
\
What is the total volume of gas, measured at room temperature and pressure (r.t.p.), produced during this decomposition?\
\
[Molar volume of gas at r.t.p. = \( 24.0\text{ dm}^3\text{ mol}^{-1} \)]

A \( 25.0\text{ cm}^3 \) sample of \( 0.120\text{ mol dm}^{-3} \) sodium thiosulfate solution, \( \text{Na}_2\text{S}_2\text{O}_3 \), reacts completely with \( 20.0\text{ cm}^3 \) of an aqueous iodine solution, \( \text{I}_2 \), according to the equation:\
\
\( 2\text{S}_2\text{O}_3^{2-}(\text{aq}) + \text{I}_2(\text{aq}) \rightarrow \text{S}_4\text{O}_6^{2-}(\text{aq}) + 2\text{I}^-(\text{aq}) \)\
\
What is the concentration of the iodine solution?

The standard enthalpy changes of combustion, \( \Delta H^\ominus_\text{c} \), for carbon, hydrogen, and propanoic acid, \( \text{CH}_3\text{CH}_2\text{CO}_2\text{H}(\text{l}) \), are shown in the table.\
\
| Substance | \( \Delta H^\ominus_\text{c} / \text{kJ mol}^{-1} \) |\
| :--- | :---: |\
| \( \text{C(s)} \) | \( -393.5 \) |\
| \( \text{H}_2(\text{g}) \) | \( -285.8 \) |\
| \( \text{CH}_3\text{CH}_2\text{CO}_2\text{H(l)} \) | \( -1527.0 \) |\
\
What is the standard enthalpy change of formation, \( \Delta H^\ominus_\text{f} \), of propanoic acid?\
\
\( 3\text{C(s)} + 3\text{H}_2(\text{g}) + \text{O}_2(\text{g}) \rightarrow \text{CH}_3\text{CH}_2\text{CO}_2\text{H(l)} \)

The equation for the hydration of ethene to ethanol is shown:\
\
\( \text{C}_2\text{H}_4(\text{g}) + \text{H}_2\text{O}(\text{g}) \rightarrow \text{C}_2\text{H}_5\text{OH}(\text{g}) \)\
\
The standard enthalpy changes of formation, \( \Delta H^\ominus_\text{f} \), are given:\
- \( \Delta H^\ominus_\text{f}[\text{C}_2\text{H}_4(\text{g})] = +52.3\text{ kJ mol}^{-1} \)\
- \( \Delta H^\ominus_\text{f}[\text{H}_2\text{O}(\text{g})] = -241.8\text{ kJ mol}^{-1} \)\
- \( \Delta H^\ominus_\text{f}[\text{C}_2\text{H}_5\text{OH}(\text{g})] = -235.1\text{ kJ mol}^{-1} \)\
\
What is the standard enthalpy change of this hydration reaction?

When 2-methylbut-1-ene, \( \text{CH}_2\text{=C(CH}_3)\text{CH}_2\text{CH}_3 \), reacts with hydrogen bromide, \( \text{HBr} \), the major organic product formed is 2-bromo-2-methylbutane.\
\
Which statement correctly explains why this is the major product?

An organic compound, \( \text{X} \), has the molecular formula \( \text{C}_6\text{H}_8 \).\
\
When \( \text{X} \) is reacted with hot, concentrated, acidified potassium manganate(VII), the only organic product obtained is propanedioic acid, \( \text{HOOC-CH}_2\text{-COOH} \).\
\
Which compound is \( \text{X} \)?

The table shows the successive ionisation energies, in \( \text{kJ mol}^{-1} \), of an element \( \text{T} \) in Period 3 of the Periodic Table.\
\
| 1st | 2nd | 3rd | 4th | 5th | 6th | 7th |\
| :---: | :---: | :---: | :---: | :---: | :---: | :---: |\
| 1000 | 2250 | 3360 | 4560 | 7010 | 8500 | 27100 |\
\
In which group of the Periodic Table is element \( \text{T} \)?

Which statement correctly explains why the first ionisation energy of sulfur is lower than that of phosphorus?

A mixture of 15 cm³ of a gaseous hydrocarbon X and 100 cm³ of oxygen (an excess) was exploded in a sealed vessel. After cooling to room temperature and pressure, the total volume of gas remaining was 70 cm³. When this remaining gas was shaken with concentrated aqueous potassium hydroxide (which absorbs carbon dioxide), the volume decreased to 25 cm³. What is the molecular formula of hydrocarbon X?

A student added 25.0 cm³ of 0.200 mol dm⁻³ aqueous copper(II) sulfate to 30.0 cm³ of 0.400 mol dm⁻³ aqueous sodium hydroxide. A blue precipitate of copper(II) hydroxide was formed: \(\text{Cu}^{2+}(\text{aq}) + 2\text{OH}^{-}(\text{aq}) \rightarrow \text{Cu(OH)}_2(\text{s})\). After filtering the mixture, what is the concentration of \(\text{OH}^{-}(\text{aq})\) remaining in the filtrate?

The standard enthalpy changes of combustion of graphite, hydrogen and butane are given in the table: graphite, \(\text{C(s)} = -394\text{ kJ mol}^{-1}\); hydrogen, \(\text{H}_2\text{(g)} = -286\text{ kJ mol}^{-1}\); butane, \(\text{C}_4\text{H}_{10}\text{(g)} = -2877\text{ kJ mol}^{-1}\). What is the standard enthalpy change of formation of butane, \(\text{C}_4\text{H}_{10}\text{(g)}\)?

Consider the reaction: \(\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \rightarrow 2\text{Fe(s)} + 3\text{CO}_2\text{(g)}\), for which the standard enthalpy change is \(-25\text{ kJ mol}^{-1}\). The standard enthalpy change of formation of \(\text{CO(g)}\) is \(-111\text{ kJ mol}^{-1}\) and that of \(\text{CO}_2\text{(g)}\) is \(-394\text{ kJ mol}^{-1}\). What is the standard enthalpy change of formation of \(\text{Fe}_2\text{O}_3\text{(s)}\)?

Which statement about the reaction between propene and hydrogen bromide, HBr, is correct?

An organic compound Y is treated with hot, concentrated, acidified potassium manganate(VII). The only organic products formed are propanone and carbon dioxide. What is the identity of compound Y?

The successive ionisation energies, in kJ mol⁻¹, of an element Z in Period 3 are shown: 1st: 578, 2nd: 1817, 3rd: 2745, 4th: 11578, 5th: 14831. In which group of the Periodic Table is element Z?

Which statement best explains why the first ionisation energy of sulfur is less than the first ionisation energy of phosphorus?

An alloy of magnesium and aluminium of mass 1.026 g was fully reacted with an excess of dilute hydrochloric acid. The chemical equations for the reactions are: Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g) and 2Al(s) + 6HCl(aq) -> 2AlCl3(aq) + 3H2(g). The total volume of hydrogen gas collected was 1.20 dm3 measured at room temperature and pressure (r.t.p.). [Assume Ar: Mg = 24.3, Al = 27.0; molar volume of gas at r.t.p. = 24.0 dm3 mol-1] (a) State the oxidation numbers of magnesium and aluminium before and after the reaction with dilute hydrochloric acid. Identify which species has been oxidized in this reaction. (3 marks) (b) Write the ionic equation, including state symbols, for the reaction of aluminium with dilute hydrochloric acid. (2 marks) (c) Using the experimental data, calculate the percentage by mass of magnesium in the alloy. Show all your working. (6 marks) (d) In a separate experiment, 3.00 g of magnesium is reacted with 1.12 dm3 of oxygen gas (measured at r.t.p.) to form magnesium oxide: 2Mg(s) + O2(g) -> 2MgO(s). Determine the limiting reactant and calculate the mass of magnesium oxide formed. (4 marks)

(a) Define the following terms: (i) Standard enthalpy change of formation. (2 marks) (ii) Standard enthalpy change of combustion. (2 marks) (b) Propan-2-ol, C3H8O(l), is a widely used solvent. (i) Write the balanced chemical equation, including state symbols, for the reaction representing the standard enthalpy change of formation of liquid propan-2-ol. (2 marks) (ii) Construct a Hess's Law cycle that can be used to determine the standard enthalpy change of formation of liquid propan-2-ol from the standard enthalpy changes of combustion of carbon, hydrogen, and propan-2-ol. (3 marks) (iii) Calculate the standard enthalpy change of formation of liquid propan-2-ol, in kJ/mol, using the following data: standard enthalpy change of combustion of C(s) = -393.5 kJ/mol, standard enthalpy change of combustion of H2(g) = -285.8 kJ/mol, and standard enthalpy change of combustion of C3H8O(l) = -2005.8 kJ/mol. (3 marks) (c) The standard enthalpy change of vaporisation of propan-2-ol is +47.5 kJ/mol. Determine the standard enthalpy change of formation of gaseous propan-2-ol, C3H8O(g). (3 marks)

(a) Pent-2-ene is a hydrocarbon with the molecular formula C5H10. It exhibits stereoisomerism. Draw and label the cis and trans (or E and Z) isomers of pent-2-ene, and explain why pent-2-ene can exhibit stereoisomerism while pent-1-ene cannot. (4 marks) (b) 2-methylbut-2-ene is another structural isomer of C5H10. (i) Complete the chemical equation below for the reaction of 2-methylbut-2-ene with cold, dilute, alkaline potassium manganate(VII), KMnO4. Draw the structural formula of the organic product and state the observed colour change: (CH3)2C=CHCH3 + [O] + H2O -> ... (3 marks) (ii) When 2-methylbut-2-ene reacts with hydrogen bromide, HBr, a mixture of two structural isomers is formed: a major product and a minor product. Draw the skeletal structures of the major and minor products. Explain, with reference to the stability of the carbocation intermediates, why one product is formed as the major product. (5 marks) (iii) 2-methylbut-2-ene is reacted with hot, concentrated, acidified potassium manganate(VII). The double bond is completely cleaved. State the structural formulas and names of the two organic products formed in this reaction. (3 marks)

(a) Define the term first ionisation energy. (3 marks) (b) Write an equation, including state symbols, that represents the third ionisation energy of sodium. (2 marks) (c) The successive ionisation energies, in kJ/mol, of a Period 3 element, Q, are shown below: 1st: 578, 2nd: 1817, 3rd: 2745, 4th: 11578, 5th: 14831, 6th: 18378. (i) Identify element Q. Justify your answer using the data provided. (3 marks) (ii) Explain why successive ionisation energies of element Q show a general increase. (2 marks) (d) Explain the following observations: (i) The first ionisation energy of sulfur is lower than that of phosphorus, even though sulfur has a greater nuclear charge. (3 marks) (ii) The first ionisation energy of magnesium is greater than that of aluminium. (2 marks)

A student performs a volumetric titration to determine the exact concentration of a monobasic acid, \( \text{HX} \).

The student is provided with:
- **FA 1**: An aqueous solution of the monobasic acid \( \text{HX} \) of unknown concentration.
- **FA 2**: \( 0.0800 \text{ mol dm}^{-3} \) standard sodium hydroxide, \( \text{NaOH} \) solution.

The student uses phenolphthalein as an indicator and records the following burette readings:
- **Rough**: Final reading = \( 24.50 \text{ cm}^3 \), Initial reading = \( 0.00 \text{ cm}^3 \)
- **Titration 1**: Final reading = \( 23.85 \text{ cm}^3 \), Initial reading = \( 0.20 \text{ cm}^3 \)
- **Titration 2**: Final reading = \( 47.70 \text{ cm}^3 \), Initial reading = \( 24.00 \text{ cm}^3 \)
- **Titration 3**: Final reading = \( 24.35 \text{ cm}^3 \), Initial reading = \( 0.65 \text{ cm}^3 \)

(a) Complete the calculation of the volume of **FA 2** added for each titration (Rough, Titration 1, Titration 2, and Titration 3).

(b) Select the concordant titres and calculate the mean titre of **FA 2** that should be used for subsequent calculations. Show your working.

(c) Calculate the number of moles of \( \text{NaOH} \) present in the mean titre volume of **FA 2** calculated in (b).

(d) Write the balanced chemical equation for the neutralisation reaction and calculate the concentration, in \( \text{mol dm}^{-3} \), of the acid **FA 1**, assuming that a \( 25.0 \text{ cm}^3 \) pipette was used to measure **FA 1** for each titration.

(e) Calculate the percentage uncertainty in the volume of **FA 2** added during Titration 1, given that each individual burette reading has an uncertainty of \( \pm 0.05 \text{ cm}^3 \).

(f) Suggest two procedural practices during a titration that would increase the precision and accuracy of the end-point determination.

A student carries out a thermochemical investigation using a simple calorimeter to determine the enthalpy change of hydration of anhydrous copper(II) sulfate using Hess's Law.

**Experiment 1**: Dissolving anhydrous copper(II) sulfate.

\( 3.99 \text{ g} \) of anhydrous \( \text{CuSO}_4 \) (\( M_{\text{r}} = 159.6 \)) was dissolved in \( 50.0 \text{ cm}^3 \) of water in a polystyrene cup. The temperature of the water increased from \( 21.5\ ^\circ\text{C} \) to \( 30.1\ ^\circ\text{C} \).

**Experiment 2**: Dissolving hydrated copper(II) sulfate.

\( 6.24 \text{ g} \) of hydrated \( \text{CuSO}_4\cdot5\text{H}_2\text{O} \) (\( M_{\text{r}} = 249.6 \)) was dissolved in \( 45.0 \text{ cm}^3 \) of water in a polystyrene cup. The temperature of the water decreased from \( 22.0\ ^\circ\text{C} \) to \( 20.8\ ^\circ\text{C} \).

[Assume the specific heat capacity of all solutions is \( 4.18 \text{ J g}^{-1}\ ^\circ\text{C}^{-1} \) and the density is \( 1.00 \text{ g cm}^{-3} \). Assume the mass of the solution is equal to the mass of the water added.]

(a) For **Experiment 1**:
(i) Calculate the heat energy released, \( q_1 \), in joules.
(ii) Calculate the molar enthalpy change of solution of anhydrous copper(II) sulfate, \( \Delta H_1 \), in \( \text{kJ mol}^{-1} \). Include the appropriate sign.

(b) For **Experiment 2**:
(i) Calculate the heat energy absorbed, \( q_2 \), in joules.
(ii) Calculate the molar enthalpy change of solution of hydrated copper(II) sulfate, \( \Delta H_2 \), in \( \text{kJ mol}^{-1} \). Include the appropriate sign.

(c) Construct a Hess's Law energy cycle to relate \( \Delta H_{\text{hyd}} \), \( \Delta H_1 \), and \( \Delta H_2 \) for the following reaction:
\( \text{CuSO}_4(\text{s}) + 5\text{H}_2\text{O}(\text{l}) \rightarrow \text{CuSO}_4\cdot5\text{H}_2\text{O}(\text{s}) \)
Calculate the enthalpy change of hydration, \( \Delta H_{\text{hyd}} \), in \( \text{kJ mol}^{-1} \).

(d) State two major sources of heat-related errors in this practical setup and how each could be minimised.

You are provided with three solutions: **FA 3**, **FA 4**, and **FA 5**, each containing one of the following compounds:
- Aqueous sodium but-2-enedioate (an alkene salt)
- Potassium chloride, \( \text{KCl} \)
- Potassium iodide, \( \text{KI} \)

You are also provided with solid **FA 6**, which is an anhydrous carbonate of a Group 2 metal.

(a) Describe the expected observations when **FA 4** and **FA 5** are tested to identify their halide ions. Tabulate your answer to show observations for:
- **Test 1**: Addition of dilute nitric acid followed by aqueous silver nitrate.
- **Test 2**: Addition of dilute aqueous ammonia to the mixture from Test 1.
- **Test 3**: Addition of concentrated aqueous ammonia to the mixture from Test 1.

(b) Write the ionic equation, including state symbols, for the precipitation reaction occurring in **Test 1** with **FA 5**.

(c) Describe a chemical test that can be carried out to confirm that **FA 3** contains a carbon-carbon double bond. State the reagent, the conditions, and the expected positive observation.

(d) A student carries out the thermal decomposition of solid **FA 6** in a test-tube and passes the gas evolved through limewater.
(i) State the observation in the limewater and write the equation for the thermal decomposition of **FA 6**, representing the metal as \( \text{M} \).
(ii) Describe the trend in the thermal stability of Group 2 carbonates down the group and explain this trend in terms of ionic radius, charge density, and polarising power of the metal cation.