AS & A Level Chemistry - 9701 Paper 1 2013 Winter Zone 3

Ammonium nitrate, \( \text{NH}_4\text{NO}_3 \), can decompose explosively when heated.

\[ \text{NH}_4\text{NO}_3 \rightarrow \text{N}_2\text{O} + 2\text{H}_2\text{O} \]

What are the changes in the oxidation numbers of the two nitrogen atoms in \( \text{NH}_4\text{NO}_3 \) when this reaction proceeds?

In the extraction of aluminium by electrolysis, why is it necessary to dissolve aluminium oxide in molten cryolite?

A $10 \text{ cm}^{3}$ sample of $0.30 \text{ mol dm}^{-3}$ $Tl^+$ $NO_3^-$ required $20 \text{ cm}^{3}$ of $0.10 \text{ mol dm}^{-3}$ acidified $NH_4VO_3$ to oxidise it to $Tl^{3+}$ in solution. Vanadium is the only element reduced in this reaction.
What is the oxidation number of the vanadium in the reduced form?

Use of the Data Booklet is relevant to this question.
Element X forms $X^-$ ions that can be oxidised to element X by acidified potassium manganate(VII).
What could be the values of the first four ionisation energies of X?
[Table_1]

Na2S2O3 reacts with dilute HCl to give a pale yellow precipitate. If 1 cm^3 of 0.1 mol dm^{-3} HCl is added to 10 cm^3 of 0.02 mol dm^{-3} Na2S2O3 the precipitate forms slowly. If the experiment is repeated with 1 cm^3 of 0.1 mol dm^{-3} HCl and 10 cm^3 of 0.05 mol dm^{-3} Na2S2O3 the precipitate forms more quickly. Why is this?

Which stage in the free radical substitution of ethane by chlorine will have the lowest activation energy?

Measured values of the pressure, volume and temperature of a known mass of a gaseous compound are to be substituted into the equation $pV = nRT$.
The measurements are used to calculate the relative molecular mass, $M_r$, of a compound.
Which conditions of pressure and temperature would give the most accurate value of $M_r$?
[Table_1: Conditions of pressure and temperature]

Which solid contains more than one kind of bonding?

When an evacuated fluorescent light tube of volume 300 cm³ is filled with a gas at 300 K and 101 kPa, the mass of the tube increases by 1.02 g. The gas obeys the ideal gas equation $pV = nRT$.
What is the identity of the gas?

Nitrogen reacts with hydrogen to produce ammonia.
$$ \text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) $$
A mixture of 1.00 mol of nitrogen, 3.00 mol of hydrogen and 1.98 mol of ammonia is allowed to reach equilibrium in a sealed vessel under certain conditions. It was found that 1.64 mol of nitrogen were present in the equilibrium mixture.
What is the value of $K_c$ under these conditions?

Use of the Data Booklet is relevant to this question.
Which calcium compound contains 54.1 % by mass of calcium?

The reaction between aluminium powder and anhydrous barium nitrate is used as the propellant in some fireworks. The reaction produces the metal oxides and nitrogen.
$$10Al + 3Ba(NO_3)_2 \rightarrow 5Al_2O_3 + 3BaO + 3N_2$$
Which mass of barium oxide is produced when 5.40 g of aluminium powder reacts with an excess of anhydrous barium nitrate?

The diagram shows some applications of compounds of Group II elements.

Which numbered links are correct?

River water in a chalky agricultural area may contain $\text{Ca}^{2+}$, $\text{Mg}^{2+}$, $\text{CO}_3^{2-}$, $\text{HCO}_3^{-}$, $\text{Cl}^{-}$ and $\text{NO}_3^{-}$ ions. In a water treatment plant, such water is treated by adding a calculated quantity of calcium hydroxide.
What will be precipitated from the river water following the addition of calcium hydroxide?

Ammonia exists as simple covalent molecules, NH$_3$. Ammonia can react with suitable reagents to form products containing ammonium ions, NH$_4^+$. Ammonia can also react with suitable reagents to form products containing amide ions, NH$_2^-$.
Which of these nitrogen-containing species are present in an aqueous solution of ammonia?

Carbon, nitrogen and sulfur are non-metals.
Which statement about their oxides, $XO_2$, is correct? (Where X represents carbon, nitrogen or sulfur.)

Which oxide is insoluble in aqueous sodium hydroxide?

The graph below shows the variation of the first ionisation energy with the number of protons for some elements. [Graph_Image_1]
Which statement is correct?

Use of the Data Booklet is relevant to this question.
Elements $J$ and $K$ react together to form compound $L$. Elements $J$ and $K$ are both in Period 3. Element $J$ has the smallest atomic radius in Period 3. There are only two elements in Period 3 which have a lower melting point than element $K$.
Which compound could be $L$?

Which diagram gives the skeletal formula of 2-bromopentan-4-ol?

Including structural and stereoisomers, how many isomers are there of $C_2H_2Br_2$?

Which reaction will give the best yield of 2-chloropropane?

Pent-2-ene, CH3CH2CH=CHCH3, reacts in a similar way to ethene.
Pent-2-ene is reacted with cold, dilute, acidified manganate(VII) ions.
What will be produced in the greatest amount?

Including structural and stereoisomers, how many isomeric products are produced when alcoholic KOH reacts with 2-chlorobutane?

Chlorofluorocarbons, CFCs, can be used as refrigerants, aerosol propellants and fire extinguishers.
CFCs such as $\text{CCl}_3\text{F}$ and $\text{CCl}_2\text{F}_2$ are more stable than chloroalkanes such as $\text{CCl}_4$.

What is the reason for their greater stability?

Halogenoalkanes react with aqueous NaOH to give alcohols. The mechanism involved is either $S_N1$ or $S_N2$.
Which halogenoalkane produces the highest percentage of product by an $S_N1$ mechanism, when treated with aqueous NaOH?

An alcohol with molecular formula $C_nH_{2n+1}OH$ has a chiral carbon atom but does not react with hot, acidified $K_2Cr_2O_7$.
What is the smallest possible value for $n$?

Compound X reacts with ethanoic acid in the presence of an $H^+$ catalyst to produce the compound below. What is the molecular formula of compound X?

How many hydrogen atoms are added to each molecule of ethanal when it is reacted with NaBH$_4$ in water?

Which fragment could appear in the chain produced by polymerising 1,1-dichloroethene?

The $^{1}H^{+}$ ion was first characterised by J. J. Thomson over a century ago. $^{6}Li$ is a rare isotope of lithium which forms the $^{6}Li^{+}$ ion.
Which statements are correct?
1. Both ions contain the same number of protons.
2. Both ions contain the same number of electrons.
3. Both ions contain the same number of neutrons.

The diagram represents the Boltzmann distribution of molecular energies at a given temperature.

Which of the factors that affect the rate of a reaction can be explained using such a Boltzmann distribution?
1. increasing the concentration of reactants
2. increasing the temperature
3. the addition of a catalyst

Methanoic acid molecules, HCO_2H, and hydrogen carbonate ions, HCO_3^-, can both behave as acids.
Why does a solution of methanoic acid have a lower pH than a solution of sodium hydrogen carbonate of the same concentration?
1. HCO_2H molecules dissociate more fully than HCO_3^- ions do.
2. Each HCO_2H molecule has two hydrogen atoms; each HCO_3^- ion only has one.
3. Methanoic acid is a weaker acid than sodium hydrogen carbonate.

The following equilibrium is an exothermic reaction in the forward direction.
$$2\mathrm{CrO_4^{2-}(aq)} + 2\mathrm{H^+(aq)} \rightleftharpoons \mathrm{Cr_2O_7^{2-}(aq)} + \mathrm{H_2O(l)}$$ What happens when the concentration of $\mathrm{CrO_4^{2-}}$ ions increases and the temperature decreases?
1. The concentration of $\mathrm{Cr_2O_7^{2-}}$ ions increases.
2. The equilibrium constant increases.
3. The activation energy decreases.

Which processes involve the conversion of sulfur dioxide into sulfur trioxide?
1 the combustion of sulfur contaminated fossil fuels
2 the Contact process for manufacturing sulfuric acid
3 the catalytic oxidation of sulfur dioxide by oxides of nitrogen

Which chlorides of Period 3 elements will form a neutral solution when added to water?
1. $\text{NaCl}$
2. $\text{Al}_2\text{Cl}_6$
3. $\text{PCl}_5$

A series of tests was carried out on the compound shown below:



Which pairs of reagents would both give a positive result for this compound?

The reaction of ethanal, $\text{CH}_3\text{CHO}$, with HCN to form a cyanohydrin is catalysed by NaCN. What are features of the intermediate of this reaction?
1 It is chiral.
2 It has a single negative charge on one of its atoms.
3 It is a nucleophile.

The ester $C_2H_5CO_2CH_2CH_3$ can be made in a school or college laboratory by a sequence of reactions using compound X as the only organic material.
What might be the identity of compound X?

The structural formulae of two compounds are shown below. Which statements about these compounds are correct?
1. The two compounds are structural isomers of each other.
2. The empirical formula of both compounds is $C_3H_6O$.
3. Both compounds are carboxylic acids.