AS & A Level Chemistry - 9701 Paper 1 2019 Winter Zone 1

The diagram shows the Boltzmann distribution of energies in a gas. The gas undergoes a reaction with an activation energy, $E_a$. The peak of the distribution is labelled P.

If the same reaction is carried out in the presence of a catalyst, which statement is correct?

Diamond is a pure form of carbon. The mass of a diamond can be measured in carats. One carat is 0.200 g of carbon.
Which expression gives the number of carats that contain $6.02 \times 10^{23}$ carbon atoms?

Which molecule or ion contains the smallest bond angle?

Four compounds are shown.

$C_2H_4$ $C_2H_5OH$ $CH_3CHO$ $CH_3CO_2H$

How many of these compounds have an odd number of $\sigma$ bonds?

Ethanol, $\text{CH}_3\text{CHO}$, ethanal, $\text{C}_2\text{H}_5\text{OH}$, and methoxymethane, $\text{CH}_3\text{OCH}_3$, are three organic compounds. Which compound has the highest boiling point and what is the interaction that causes this boiling point to be the highest? [Table_1]

What is the oxidation number of sulfur in each species? [Table_1]

The following data are needed for this question.
$\Delta H_f^\circ (\text{N}_2\text{H}_4(l)) = 50.6\, \text{kJ}\, \text{mol}^{-1}$
$\Delta H_f^\circ (\text{N}_2\text{O}_4(g)) = 9.2\, \text{kJ}\, \text{mol}^{-1}$
$\Delta H_f^\circ (\text{H}_2\text{O}(g)) = -241.8\, \text{kJ}\, \text{mol}^{-1}$

Hydrazine, N$_2$H$_4$(l), reacts with dinitrogen tetraoxide, N$_2$O$_4$(g), to form nitrogen gas and water vapour.

$2\text{N}_2\text{H}_4(l) + \text{N}_2\text{O}_4(g) \rightarrow 3\text{N}_2(g) + 4\text{H}_2\text{O}(g)$

What is the enthalpy change for this reaction?

Sodium burns in oxygen giving out heat energy and forming the compound Na2O. The equation for this reaction is shown:
2Na(s) + \( \frac{1}{2} \)O2(g) \rightarrow Na2O(s)
Which statement about the reaction is correct?

In the chemical equation, w, x, y and z are all whole numbers.

$$wClO_3^- + xMnO_4^- + yH^+ \rightarrow wClO_4^- + xMnO_2 + zH_2O$$

When the equation is balanced, what are w, x and y?

Two compounds X and Y react to produce compound Z. The reaction is reversible.
$$X + Y \rightleftharpoons Z$$
When X and Y are mixed together in a closed system, a dynamic equilibrium is gradually established.
Which graph could represent the change in the rates of the forward and reverse reactions over time?

[Graph_1]
key
...... rate of forward reaction
----- rate of reverse reaction

The reaction between sulfur dioxide and oxygen is reversible.
$$2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) \quad K_c = 280 \text{ mol}^{-1} \text{ dm}^3 \text{ at 1000 K}$$
In an equilibrium mixture at 1000 K the sulfur dioxide concentration is 0.200 mol dm⁻³ and the oxygen concentration is 0.100 mol dm⁻³.
What is the sulfur trioxide concentration?

Which oxide will cause an increase in pH when added to water?

X, Y and Z are consecutive elements in Period 3 of the Periodic Table. Element Y has the highest first ionisation energy and the lowest melting point of these three elements.
What are the identities of X, Y and Z?

A 5.00g sample of an anhydrous Group 2 metal nitrate loses 3.29g in mass when heated strongly.
Which metal is present?

Solutions P and Q each contain a different Group 2 ion at the same concentration. One contains $\text{Mg}^{2+}$, the other contains $\text{Ba}^{2+}$. Tests are carried out on separate $5 \, \text{cm}^3$ samples of P and Q.

test 1: add $1 \, \text{cm}^3$ of $0.1 \, \text{mol}\, \text{dm}^{-3}$ Na$_2$SO$_4$(aq)
test 2: add $1 \, \text{cm}^3$ of $0.1 \, \text{mol}\, \text{dm}^{-3}$ NaOH(aq)

What are the results of these tests?

[Table_1]

Chlorine and bromine have different volatilities.
Which row identifies the more volatile of the two elements, and gives the correct explanation? [Table_1]

Sodium azide, NaN₃, is dissolved in water. Acidified silver nitrate is added to the solution and a white precipitate forms. Aqueous ammonia is then added to the white precipitate.
The azide ion, N₃⁻, has similar chemical properties to the Cl⁻ ion.
Which row of the table can be predicted from this information?
[Table_1]

Which type of reaction occurs when solid ammonium sulfate is heated with an excess of sodium hydroxide solution?

Catalytic converters are fitted in the exhaust systems of many cars. Which gas:
• causes acid rain if it is released into the air
• is removed from car exhaust fumes by a catalytic converter?

Which substance reacts with trichloroethene to give a chiral product?

Alkanes are saturated hydrocarbons.
Which type of reaction are alkanes most likely to undergo?

An alkene reacts with hot, concentrated, acidified potassium manganate(VII) to produce a single organic product as shown.

What is the structure of the alkene?

A tertiary bromoalkane, indicated here by $\small ext{>}$C--Br, reacts with aqueous NaOH. The mechanism has the reaction pathway shown. Which point in the diagram is correctly identified?

Bromoethane and chloroethane are added separately to water. Hydrolysis reactions occur. Which compound hydrolyses more rapidly and what is the mechanism? [Table_1]

Alcohol X is oxidised to form compound Y.
The composition of Y is 54.54% carbon, 36.36% oxygen and 9.10% hydrogen. The $M_r$ of Y is 88.0.
What could be the structure of alcohol X?

The diagram shows the structure of compound Z.
What is the product of the reaction between compound Z and an excess of NaBH₄?

Compound Q shows the following reactions.
• It gives an orange precipitate with 2,4-dinitrophenylhydrazine.
• It gives a red-brown precipitate with Fehling’s reagent.
• It gives a pale yellow precipitate with alkaline aqueous iodine.

What could be the identity of Q?

Tartaric acid, $HO_2CCH(OH)CH(OH)CO_2H$, is found in many plants.
A sample of tartaric acid reacts with an excess of $LiAlH_4$ to form the organic product J.
What happens when $NaOH(aq)$ is added to separate samples of tartaric acid and J?

When CH$_2$(OH)CH=CHCO$_2$H is warmed with a little concentrated sulfuric acid, a cyclic compound is formed.
What is the skeletal formula of the cyclic compound?

The infra-red spectrum of compound P is shown.

What could be compound P?

A particular atom of germanium, Ge, has a nucleon number of 70.
Which statements about a $^{70}_{32}$Ge atom are correct?
1. It has the same number of electrons as a $^{79}_{34}$Se$^{2+}$ ion.
2. It has the same number of neutrons as an atom of $^{68}_{30}$Zn.
3. It has half as many protons as an atom of $^{160}_{64}$Gd.

The first ionisation energy of chlorine is greater than that of sulfur.
Which factors contribute to this?
1. Chlorine has more protons in its nucleus than sulfur does.
2. Chlorine has greater electron shielding than sulfur does.
3. The covalent bonds in chlorine molecules are stronger than those in sulfur molecules.

Liquids X and Y do not react with one another. They have identical boiling points. When a particular volume of X is shaken with a similar volume of Y, they form a liquid mixture Z. The average intermolecular forces in liquid Z are stronger than the average of the forces in X and the forces in Y.
Which deductions from this information are correct?
1. The mixing of X and Y is exothermic.
2. The vapour pressure of liquid Z will be less than that of either liquid X or liquid Y at the same temperature.
3. The boiling point of liquid Z will be lower than that of either liquid X or liquid Y at the same pressure.

The stoichiometry of a catalysed reaction is shown by the equation below.
P (g) + Q (g) \rightleftharpoons R (g) + S (l)
Two experiments are carried out in which the amount of R is measured. The results are shown in the diagram.

Which changes in the conditions could explain the results shown?
1. A lower pressure was used in experiment 2.
2. A different catalyst was used in experiment 2.
3. Product S was continuously removed from the reaction vessel in experiment 2.

Which statements are correct?
1. Chloride ions are oxidised when concentrated sulfuric acid is added to NaCl(s).
2. A disproportionation reaction takes place when chlorine is added to cold NaOH(aq).
3. An acidic solution forms when chlorine is added to water.

Nitrogen gas is unreactive, whereas oxygen gas and chlorine gas are reactive.
Which statements help to explain this difference?

1. The two N atoms in an $\text{N}_2$ molecule are held together by a very strong triple bond.
2. The triple bond between two N atoms is not polar. The bonds in $\text{O}_2$ and $\text{Cl}_2$ are polar.
3. The atoms in $\text{N}_2$ have a full outer shell of electrons. The atoms in $\text{O}_2$ and $\text{Cl}_2$ do not have a full outer shell of electrons.

The structure of tiglic acid is $CH_3CH=C(CH_3)CO_2H$.
Which statements about the properties of one molecule of this acid are correct?

Which compounds, on heating with an excess of concentrated sulfuric acid, produce only one product with molecular formula $C_7H_{10}$?

Hydrogen cyanide reacts with propanone in the presence of potassium cyanide.
Which statements about this reaction are correct?

1. The cyanide ion is a catalyst for the reaction.
2. This is an addition reaction.
3. The intermediate behaves as a base.

Which compounds produce three different organic products when hydrolysed?