Edexcel A Level Chemistry Paper 1: Advanced Inorganic and Physical Chemistry June 2017 question paper 9CH0/01

1h 45m 90 marks

10 questions

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A phosphorus atom has mass number 31.

(a)

How many of each sub-atomic particle are present in the phosphide ion, P^3–?

(1)

Answer

(b)

(b)(i)

Explain why a phosphorus(III) chloride molecule has this shape and bond angle.

(2)

Answer

(b)(ii)

Which describes the polarity of the P—C l bond and the polarity of the phosphorus(III) chloride molecule?

(1)

Answer

(c)

Phosphorus has one naturally occurring isotope with mass number 31. Chlorine exists as two isotopes with mass numbers 35 and 37.

Give the formulae and mass/charge ratio of the ions responsible for the molecular ion peaks in the mass spectrum of phosphorus(III) chloride, PCl₃.

(2)

Answer

Magnesium nitrate decomposes on heating as shown by the equation.

$Question 2, shown as an image$

(a)

Explain, in terms of all the relevant oxidation numbers, why this is a redox reaction.

(3)

Answer

(b)

Calcium nitrate decomposes in a similar way to magnesium nitrate, but requires a higher temperature for decomposition.

Explain this observation in terms of the charge and size of the cations.

(3)

Answer

This question is about halogens and redox reactions.

(a)

The boiling temperatures of three halogens are shown in the table.

Halogen	Boiling temperature / °C
chlorine	–35
bromine	59
iodine	184

Explain why the boiling temperatures increase from chlorine to iodine.

(2)

Answer

(b)

Potassium halides react with concentrated sulfuric acid to form potassium hydrogensulfate and the different products shown in the table.

By referring to any changes in oxidation numbers when these halides react with concentrated sulfuric acid, explain which halide is the strongest reducing agent.

(3)

Answer

(c)

Use these electrode potentials to answer the following questions.

Electrode reaction	E / V
I₂(aq) + 2e^– 2I^–(aq)	+0.54
Fe³⁺(aq) + e^– Fe²⁺(aq)	+0.77
Br₂(aq) + 2e^– 2Br^–(aq)	+1.09
MnO₂(s) + 4H⁺(aq) + 2e^– Mn²⁺(aq) + 2H₂O(l)	+1.23
Cl₂(aq) + 2e^– 2Cl^–(aq)	+1.36
MnO₄^–(aq) + 8H⁺(aq) + 5e^– Mn²⁺(aq) + 4H₂O(l)	+1.51

(c)(i)

Which species will oxidise Fe²⁺(aq) to Fe³⁺(aq)?

$Question 3, shown as an image$

(1)

Answer

(c)(ii)

Write the ionic equation and calculate the $fraction$ value for the reaction between MnO₄^– maths symbol ions in acidic solution. State symbols are not required.

(3)

Answer

Iron and zinc are in the d-block of the Periodic Table.

(a)

Which of these is the electronic configuration of an iron(II) ion, Fe²⁺?

(1)

Answer

(b)

Iron(II) ions, [Fe(H₂O)₆]²⁺, form a pale green solution but zinc ions, [Zn(H₂O)₆]²⁺, form a colourless solution.

Explain why zinc ions are colourless.

(2)

Answer

(c)

Hydrated iron(II) ions react with ethanedioate ions, C₂O₄^2–, to form a complex ion.

$Question 4, shown as an image$

(c)(i)

Draw a structure of the [Fe(C₂O₄)₂(H₂O)₂]^2– ion, showing all of the bonds.

(2)

Answer

(c)(ii)

Explain, in terms of entropy, why this reaction is feasible.

(2)

Answer

(d)

Iodide ions, I^–, react with peroxodisulfate(VI) ions, S₂O₈^2–

$Question 4, shown as an image$

This reaction is catalysed by iron(II) ions, Fe²⁺(aq).

Write two ionic equations to show how iron(II) ions act as a catalyst in this reaction. State symbols are not required.

(2)

Answer

This question is about enthalpy changes and entropy changes.

(a)

(1)

Answer

(b)

(3)

Answer

(c)

(1)

Answer

(d)

(1)

Answer

(e)

(3)

Answer

Magnesium bromide, MgBr₂, is an ionic compound.

(a)(i)

Draw a dot-and-cross diagram to show the bonding in magnesium bromide. Only outer shell electrons are required.

(1)

Answer

(a)(ii)

State all the conditions under which magnesium bromide conducts electricity.

(1)

Answer

(b)

(b)(i)

Complete the Born-Haber cycle for magnesium bromide with formulae, electrons and labelled arrows. The cycle is not drawn to scale.

(3)

Answer

(b)(ii)

Calculate the first electron affinity of bromine, in kJ mol^–1.

(2)

Answer

(c)(i)

The first ionisation energy of sodium is 496 kJ mol^–1.

Explain why the first ionisation energy of magnesium is higher than that of sodium.

(3)

Answer

(c)(ii)

Write the equation, including state symbols, to show the third ionisation energy of magnesium.

(1)

Answer

In acid-base neutralisation reactions, there is a temperature change.

(a)

(3)

Answer

(b)

*(b) The table shows the enthalpy changes of reaction when 1 mol of different acids are neutralised by sodium hydroxide solution, at 298 K.

Acid	Enthalpy change of reaction for 1 mol of acid / kJ mol^–1
hydrochloric acid, HCl	–58
nitric acid, HNO₃	–58
sulfuric acid, H₂SO₄	–115
ethanoic acid, CH₃COOH	–56

Comment on the relative enthalpy changes of reaction, using the data from the table and including any relevant equations.

(6)

Answer

8 2-Hydroxyethanoic acid, also known as glycolic acid, CH₂OHCOOH, is an alpha hydroxy acid used in some skincare products. It has a K_a value of 1.5 × 10^–4 mol dm^–3.

The structure of glycolic acid is

(a)

A solution of glycolic acid of concentration 0.1 mol dm^–3 has a pH of 2.4

What is the approximate pH of the resulting solution after it has been diluted by a factor of 100?

A 1.4

B 2.4

C 3.4

D 4.4

(1)

Answer

(b)

Another solution of glycolic acid has a pH of 2.0

Calculate the concentration of this solution.

(3)

Answer

(c)

The titration curve for adding glycolic acid to 25.0 cm³ of 0.100 mol dm^–3 sodium hydroxide is shown.

Volume of glycolic acid / cm³

(c)(i)

Use the information given in your Data Booklet to select a suitable indicator for this titration, including the colour change you would expect to see.

Justify your selection.

(3)

Answer

(c)(ii)

What is the concentration of this glycolic acid in mol dm^–3?

$Question 8, shown as an image$

(1)

Answer

(c)(iii)

The pH of the solution containing just sodium glycolate and water is

A 2.8

B 6.0

C 8.3

$Question 8, shown as an image$

(1)

Answer

(d)

Glycolic acid has an acid dissociation constant of 1.5 × 10^–4 mol dm^–3 compared with a value of 1.7 × 10^–5 mol dm^–3 for ethanoic acid.

(d)(i)

Give a possible explanation as to why the value of K_a for glycolic acid is approximately ten times larger than that of ethanoic acid.

(2)

Answer

(d)(ii)

Complete the equation to show the conjugate acid-base pairs that would be produced when pure samples of glycolic acid and ethanoic acid are mixed.

CH₂OHCOOH + CH₃COOH maths symbol _........ +_........

(1)

Answer

This question is about buffer solutions.

(a)

A buffer solution is formed from disodium hydrogenphosphate, containing HPO₄^2– ions, and sodium dihydrogenphosphate, containing H₂PO₄^– ions.

Write the ionic equations involving HPO₄^2– and H₂PO₄^– ions to show how this solution acts as a buffer solution.

(2)

Answer

(b)

Another buffer solution was formed by mixing 20.0 cm³ of sodium hydroxide solution of concentration 0.100 mol dm^–3 with 25.0 cm³ of ethanoic acid of concentration 0.150 mol dm^–3.

CH₃COOH + NaOH maths symbol CH₃COONa + H₂O

Calculate the pH of this buffer solution.

[K_a for ethanoic acid = 1.74 × 10^–5 mol dm^–3]

(5)

Answer

Hydrogen is produced on a large scale by several different processes.

(a)

One process for producing hydrogen involves reacting white-hot carbon with steam.

$Question 10, shown as an image$

The expression for the equilibrium constant, K_p, is

(a)(i)

Give a reason why the partial pressure of carbon is not included in the expression.

(1)

Answer

(a)(ii)

Explain the effect of an increase in pressure on the equilibrium position of this reaction.

(2)

Answer

(a)(iii)

Explain, by reference to any change in the value of K_p, the effect of an increase in temperature on the equilibrium position of this reaction.

(2)

Answer

(a)(iv)

At 1000 K and a total pressure of 2.0 atm, 1.00 mol of steam reacted with excess carbon.

At equilibrium, 0.81 mol of hydrogen was present.

Calculate the value of K_p at 1000 K, stating any units.

(4)

Answer

(b)

Carbon monoxide reacts with steam.

$Question 10, shown as an image$

At 1100 K, K_c = 1.00

In an experiment, 1 mol of carbon monoxide was mixed with 1 mol of steam, 2 mol of carbon dioxide and 2 mol of hydrogen.

Deduce, with reasons, the direction in which the reaction will shift to reach equilibrium.

(3)

Answer

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Edexcel 9CH0 · Paper 1

Question 1

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Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10