AS & A Level Chemistry - 9701 Paper 1 2015 Summer Zone 1

The diagram shows a Boltzmann distribution of molecular energies for a gaseous mixture. The distribution has a peak, labelled P on the diagram.
What happens when an effective catalyst is added to the mixture?

Which quantity gives the best indication of the relative strengths of the hydrogen bonds between the molecules in liquid hydrogen halides?

Use of the Data Booklet is relevant to this question.
1.00 g of carbon is combusted in a limited supply of pure oxygen. 0.50 g of the carbon combusts to form CO2 and 0.50 g of the carbon combusts to form CO.
The resultant mixture of CO2 and CO is passed through excess NaOH(aq) and the remaining gas is then dried and collected.
What is the volume of the remaining gas? (All gas volumes are measured at 25°C and 1 atmosphere pressure.)

In oxygen difluoride, $\text{OF}_2$, fluorine has an oxidation number of $-1$. $\text{OF}_2$ will react with sulfur dioxide according to the following equation:
$$\text{OF}_2 + \text{SO}_2 \rightarrow \text{SO}_3 + \text{F}_2$$
What is oxidised and what is reduced in this reaction?

Use of the Data Booklet is relevant to this question.
The gas laws can be summarised in the ideal gas equation below.

$pV = nRT$

0.96 g of oxygen gas is contained in a glass vessel of volume $7.0 \times 10^{-3}\text{m}^3$ at a temperature of $30^\circ\text{C}$.
Assume the gas behaves as an ideal gas.

What is the pressure in the vessel?

One mole of phosphorus(V) chloride, $\text{PCl}_5$, is heated to 600 K in a sealed flask of volume 1 dm$^3$. Equilibrium is established and measurements are taken.
$$\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g)$$
The experiment is repeated with one mole of phosphorus(V) chloride heated to 600 K in a sealed flask of volume 2 dm$^3$.
How will the measurements vary?

The standard enthalpy changes of combustion of glucose and ethanol are given as −2820 and −1368 kJ molˉ¹ respectively.

Glucose, C$_6$H$_{12}$O$_6$, can be converted into ethanol.

C$_6$H$_{12}$O$_6$(s) → 2C$_2$H$_5$OH(l) + 2CO$_2$(g)

What is the standard enthalpy change for this reaction?

In which reaction is the underlined substance acting as a base?
A. $\text{HNO}_3 + \underline{\text{H}_2\text{SO}_4} \rightarrow \text{H}_2\text{NO}_3^+ + \text{HSO}_4^-$
B. $\text{HSiO}_3^- + \underline{\text{HCN}} \rightarrow \text{CN}^- + \text{H}_2\text{O} + \text{SiO}_2$
C. $\text{HNO}_2 + \underline{\text{HCO}_3^-} \rightarrow \text{H}_2\text{O} + \text{CO}_2 + \text{NO}_2^-$
D. $\text{C}_6\text{H}_5\text{O}^- + \underline{\text{CH}_2\text{ClCO}_2\text{H}} \rightarrow \text{C}_6\text{H}_5\text{OH} + \text{CH}_2\text{ClCO}_2^-$

One molecule of haemoglobin, Hb, can bind with four molecules of oxygen according to the following equation.
$$\text{Hb(aq)} + 4\text{O}_2\text{(aq)} \rightleftharpoons \text{Hb(O}_2\text{)}_4\text{(aq)}$$
When the equilibrium concentration of $\text{O}_2$ is $7.6 \times 10^{-6}$ mol dm$^{-3}$, the equilibrium concentrations of Hb and Hb(O$_2$)$_4$ are equal.
What is the value of $K_c$ for this equilibrium?

The double bond between the two carbon atoms in an ethene molecule consists of one \( \sigma \) bond and one \( \pi \) bond.
Which orbitals overlap to form each of these bonds?
[Table_1]

The diagram shows a reaction pathway for an endothermic reaction.
Which arrow represents the activation energy for the forward reaction?

In the industrial electrolysis of brine to manufacture chlorine, the diaphragm used is a porous screen which allows the flow of electrolytes but keeps other chemicals separate.

Which substance needs to be kept separate from the chlorine by the diaphragm?

The three minerals below are obtained from mines around the world. Each one behaves as a mixture of two carbonate compounds. They can be used as fire retardants because they decompose in the heat, producing $CO_2$. This gas smothers the fire.

barytocite $BaCa(CO_3)_2$
dolomite $CaMg(CO_3)_2$
huntite $Mg_3Ca(CO_3)_4$

What is the order of effectiveness as fire retardant, from best to worst?

Which observations are made when a sample of silicon chloride, SiCl₄, is added to a beaker of water?

Which diagram correctly shows the atomic radii of the elements Mg, Al, Si and P plotted against their melting points?

Chlorine is widely used in water treatment plants.
Which reaction takes place when chlorine dissolves in water?

Astatine, At, is below iodine in Group VII of the Periodic Table. Which statement is most likely to be correct?

Mohr’s salt is a pale green crystalline solid which is soluble in water. It contains two cations, one of which is $\text{Fe}^{2+}$, and one anion which is $\text{SO}_4^{2-}$.
The identity of the second cation was determined by heating Mohr’s salt with aqueous sodium hydroxide. A colourless gas was evolved which readily dissolved in water giving an alkaline solution.
A green precipitate was also formed.
What are the identities of the gas and the precipitate?

Which mass of solid residue will be obtained from the thermal decomposition of 4.10 g of anhydrous calcium nitrate?

Which reagent will give a different observation with compounds P and Q?
HOCH_2CH(OH)CHO
P
HOCH_2COCH_2OH
Q

The cyclic compound M is heated with dilute hydrochloric acid. [Image_1: Compound M structure]
What are the products of the reaction?

Cottonseed oil contains large amounts of polyunsaturated carboxylic acids. When this oil is used to make margarine, the C=C double bonds in the unsaturated carboxylic acids are hydrogenated. What reagents and conditions would be suitable to bring about this hydrogenation reaction?

Which intermediate ion forms in the greatest amount during the addition of HBr to propene?

Coniine is the major constituent of the poison 'oil of hemlock'.

Coniine can be synthesised by reacting ammonia with a dibromo compound, X.
NH$_3$ + C$_8$H$_{16}$Br$_2$ → coniine + 2HBr
X
What is the name of compound X?

2-bromopropane reacts with a hot concentrated solution of sodium hydroxide in ethanol.
Which substance is the major product of this reaction?

The presence of a halogen in an organic compound may be detected by warming the organic compound with aqueous silver nitrate.
Which compound would be the quickest to produce a precipitate?

Which reagent will give a different observation with compounds W and X?

In 1869 Ladenburg suggested a structure for benzene, $C_6H_6$, in which one hydrogen atom is attached to each carbon atom. [Image_1: Ladenburg structure]
A compound $C_6H_4Cl_2$ could be formed with the same carbon skeleton as the Ladenburg structure. How many structural isomers would this compound have?

The citrus flavour of lemons is due to the compound limonene, present in both the peel and the juice. What is the mole ratio of carbon dioxide to water produced when limonene is completely burnt in oxygen? [Table_1]

What is the organic product when ethanamide, CH$_3$CONH$_2$, is boiled with excess aqueous sodium hydroxide?

The isotope $^{99}_{\phantom{9}43}\text{Tc}$ is radioactive and has been found in lobsters and seaweed adjacent to nuclear fuel reprocessing plants.
Which statements are correct about an atom of $^{99}_{\phantom{9}43}\text{Tc}$?
1 It has 13 more neutrons than protons.
2 It has 43 protons.
3 It has 99 nucleons.

Urea is a product of animal metabolism. It can also be used as a fertiliser.

The diagram shows angle x in this molecule.
Which statements about the structure of urea are correct?
1. Angle x is approximately 120°.
2. The molecule has two $\pi$ bonds.
3. The molecule has only three lone pairs of electrons.

Aluminium is extracted from aluminium oxide by electrolysis. Which statements are correct?
1. Aluminium oxide has an extremely high melting point.
2. Bauxite is added to the aluminium oxide to lower its melting point.
3. Oxygen produced at the graphite cathode reacts with the graphite to produce $\text{CO}_2$.

Why does raising the pressure of a fixed mass of gaseous reactants at a constant temperature cause an increase in the rate of reaction?
1 More collisions occur per second when the pressure is increased.
2 More molecules have energy greater than the activation energy at the higher pressure.
3 Raising the pressure lowers the activation energy.

Which statements about the industrial manufacture of sulfuric acid are correct?
1. Sulfur is burned to form sulfur dioxide.
2. The stage that forms sulfur trioxide involves a $V_2O_5$ catalyst.
3. The stage that forms sulfur trioxide is non-reversible.

X is a Group II metal. It forms a sulfate which is more soluble than barium sulfate. It forms a hydroxide which is more soluble than calcium hydroxide.
What could be the identity of X?

The diagram shows the structure of an alkene molecule.
Which statements about this molecule are correct?
1. All the carbon atoms are in the same plane.
2. It has geometrical isomers.
3. It is optically active.

An organic compound, $X$, will react with calcium metal to produce a salt with the empirical formula $\text{CaC}_4\text{H}_4\text{O}_4$.
What could be the identity of $X$?

Which compounds will react with HBr to give the compound R?

5-hydroxypentanoic acid is readily converted into the cyclic compound L. Which statements about this reaction are correct?

1. Acidified sodium dichromate(VI) is used as a reagent.
2. A water molecule is produced in the reaction.
3. The reaction is catalysed by concentrated H₂SO₄.