AS & A Level Chemistry - 9701 Paper 1 2016 Winter Zone 1

The diagram represents, for a given temperature, the Boltzmann distribution of the kinetic energies of the molecules in a mixture of two gases that react together. The activation energy for the reaction, $E_a$, is marked.

The dotted curves below show the Boltzmann distribution for the same reaction at a higher temperature. On these diagrams, $H$ represents the activation energy at the higher temperature.
Which diagram is correct?

In the ideal gas equation, $pV = nRT$, what are the units of $n$ and $T$?

The reaction between acidified dichromate(VI) ions, $\text{Cr}_2\text{O}_7^{2-}$, and aqueous Fe$^{2+}$ ions results in the dichromate(VI) ions being reduced to Cr$^{3+}$ ions.
What is the correct equation for this reaction?

Sodium azide, NaN₃ is an explosive used to inflate airbags in cars when they crash. It consists of positive sodium ions and negative azide ions.
What are the numbers of electrons in the sodium ion and the azide ion?

The $^{68}\text{Ge}$ isotope is medically useful because it undergoes a natural radioactive process to give an isotope of a different element, $^{68}\text{X}$, which can be used to detect tumours. This transformation of $^{68}\text{Ge}$ occurs when an electron enters the nucleus and changes a proton into a neutron.
Which statement about the composition of an atom of $^{68}\text{X}$ is correct?

Histamine is produced in the body to help fight infection. Its shape allows it to fit into receptors which expand blood vessels.
[Image_1: Structure of histamine]
What are the bond angles $x$, $y$ and $z$ in histamine, from the smallest to the largest?

The approximate percentage composition of the atmospheres on four different planets is given in the table below.
Which mixture of gases has the greatest density?
[Table:
planet | major gases / % by number of molecules
H₂ He CH₄
A Jupiter 89.8 10.2 0.0
B Neptune 80.0 19.0 1.0
C Saturn 96.3 3.3 0.4
D Uranus 82.5 15.2 2.3 ]

An important reaction in the manufacture of nitric acid is the catalytic oxidation of ammonia.
$$4\text{NH}_3(g) + 5\text{O}_2(g) \rightleftharpoons 4\text{NO}(g) + 6\text{H}_2\text{O}(g)$$
For every mole of $\text{O}_2$ that reacts in this way, 181.8 kJ of energy are released.
A factory makes $2.50 \times 10^5$ mol of NO every day.
How much energy, in kJ, is released every day?

Sodium chromate(VI), Na2CrO4, is manufactured by heating chromite, FeCr2O4, with sodium carbonate in an oxidising atmosphere. Chromite contains $\text{Cr}_2\text{O}_4^{2-}$ ions.
$$2\text{FeCr}_2\text{O}_4 + 4\text{Na}_2\text{CO}_3 + 3\frac{1}{2}\text{O}_2 \rightarrow 4\text{Na}_2\text{CrO}_4 + \text{Fe}_2\text{O}_3 + 4\text{CO}_2$$
What happens in this reaction?

The table shows the partial pressures in an equilibrium mixture formed by the Haber process.

[Table_1]

$$ \text{substance} \quad \text{partial pressure / kPa} $$
nitrogen \quad 7000
hydrogen \quad 8000
ammonia \quad 4000

$$ 3\text{H}_2(g) + \text{N}_2(g) \rightleftharpoons 2\text{NH}_3(g) $$

What is the numerical value of the equilibrium constant, $K_p$, for this reaction?

An autocatalytic reaction is a reaction in which one of the products catalyses the reaction.
Which curve would be obtained if the rate of an autocatalytic reaction is plotted against time?

1.15g of a metallic element needs 300cm$^3$ of oxygen for complete reaction, at 298K and 1 atm pressure, to form an oxide which contains O$^{2-}$ ions.
What could be the identity of this metallic element?

The diagram shows the melting points of eight elements with consecutive atomic numbers. Which element could be sodium?

The properties of chlorine, bromine and their compounds are compared.
Which property is smaller for chlorine than for bromine?

At 550°C nitrogen dioxide reacts with unburnt hydrocarbon fragments such as CH₃• in the catalytic converter of a motor vehicle.
$$4CH_3• + 7NO_2 \rightarrow \frac{3}{2}N_2 + 4CO_2 + 6H_2O$$
The following table lists types of energy change for this reaction and possible reasons for them.
Which row gives the energy change for this reaction and the reason for it?
[Table_1]

Magnesium nitrate, Mg(NO_3)_2, will decompose when heated to give a white solid and a mixture of gases. One of the gases released is an oxide of nitrogen, X.
7.4 g of anhydrous magnesium nitrate is heated until no further reaction takes place.
What mass of X is produced?

Compound T is a white crystalline solid.

When a sample of T was mixed with aqueous sodium hydroxide and heated, a pungent smelling gas was produced which turned damp red litmus paper blue. This same gas produced dense white smoke with hydrogen chloride gas.

Further testing of a solution of T with barium chloride solution produced a dense white precipitate which did not dissolve when dilute hydrochloric acid was added to the mixture.

What is the identity of compound T?

Which row of the table gives correct comparisons between the solubilities of calcium and barium hydroxide and the thermal stabilities of calcium and barium carbonate?
[Table_1]

X, Y and Z represent different halogens. The table shows the results of nine experiments in which aqueous solutions of $X_2$, $Y_2$ and $Z_2$ were separately added to separate aqueous solutions containing $X^-$, $Y^-$ and $Z^-$ ions.

[Table_1]

Which row of the following table contains the ions $X^-$, $Y^-$ and $Z^-$ in order of their decreasing strength as reducing agents?

[Table_2]

In 1865 Kekulé suggested a ring structure for benzene, $C_6H_6$, in which a hydrogen atom is attached to each carbon atom. Kekulé structure In this structure all of the bonds remain in the places shown. Assuming this is the structure of benzene, how many isomers of dichlorobenzene, $C_6H_4Cl_2$, would exist?

The diagram shows the structure of vitamin A.
How many chiral centres are present in one vitamin A molecule?

PVC is difficult to dispose of. Two possible methods are burying it in landfill sites and disposal by combustion.
Which row of the table is correct?
[Table_1]

Part of the structure of a fungicide, strobilurin, is shown. R and R' are inert groups.

In this reaction, strobilurin is warmed with aqueous sulfuric acid producing compound X. Compound X is then treated with hydrogen in the presence of a nickel catalyst producing compound Y.
What could be the structure of compound Y?

Chloroethane can be used to make sodium propanoate.
chloroethane → Q → sodium propanoate
The intermediate, Q, is hydrolysed with boiling aqueous sodium hydroxide to give sodium propanoate.
Which reagent would produce the intermediate, Q, from chloroethane?

X, Y and Z are three isomeric alcohols.

• X: CH3CH2CH2CH2CH2OH
• Y: CH3CH2CH(OH)CH2CH3
• Z: (CH3)2C(OH)CH2CH3

Two or more of these alcohols react with mild oxidising agents.

One of these alcohols, when dehydrated, will give a pair of cis-trans isomers with molecular formula C5H10.

Which is correct?

Propanone reacts with an aqueous mixture of HCN and NaCN by a nucleophilic addition mechanism.
The first stage of the mechanism involves attack by cyanide ions.
Which diagram correctly represents this?

P, Q and R are carbonyl compounds.
Fehling’s solution can be used to help identify these compounds.
Which compounds form a red-brown precipitate on warming with Fehling’s solution?

Which reaction would not give ethanoic acid?

Which formula represents an ester that will form propanoic acid on hydrolysis with dilute sulfuric acid?

A solvent, X, used in printing inks has a molecular formula C₆H₁₀O₄. It may be made by reacting ethane-1,2-diol with ethanoic acid in the presence of an acid catalyst.
[Image_1: Structure of ethane-1,2-diol]
What is the structure of solvent X?

A sample of boron contains aluminium as the only impurity. A mass spectrum of the mixture shows three lines corresponding to three ions, $X^+$, $Y^+$ and $Z^+$.
[Table_1]
Which statements are correct?
1. There are more electrons in $Z^+$ than in $X^+$.
2. The $A_r$ of boron in the sample is 10.83 to four significant figures.
3. There are more protons in $Y^+$ than in $X^+$.

Which elements can form $\pi$ bonds in their compounds?

For which enthalpy changes is the value of $\Delta H$ always negative?

In the manufacture of sulfuric acid, the following exothermic reaction occurs:

$2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$

Which changes will move the position of the equilibrium to the right?
1. increasing the pressure
2. increasing the temperature
3. using twice as much catalyst

Water is added to anhydrous aluminium chloride to make a 0.1 mol dm^-3 solution.
Which observations are correct?
1. The reaction is endothermic.
2. The solution is acidic.
3. The solution contains the ion $[Al(H_2O)_6]^{3+}.$

Catalytic converters are used to modify exhaust emissions from motor vehicles. Which reactions occur in catalytic converters?
1. $C_8H_{18} + 12\frac{1}{2}O_2 \to 8CO_2 + 9H_2O$
2. $2NO + 2CO \to N_2 + 2CO_2$
3. $NO + SO_3 \to NO_2 + SO_2$

Which compounds would produce a carboxylic acid and a ketone when treated with hot, concentrated, acidified KMnO$_4$?

Bromoethane reacts with NaOH in different ways depending on the solvent used. Which statements about these reactions are correct?
[Table_1]

The responses A to D should be selected on the basis of [Table_1]
No other combination of statements is used as a correct response.
Several structural isomers of $C_3H_6O_3$ are listed below.
HOCH$_2$COCH$_2$OH
HOCH$_2$CH(OH)CHO
HOCH$_2$CH$_2$CO$_2$H
CH$_3$CH(OH)CO$_2$H
Which statements about these structural isomers are correct?
1. One mole of each reacts with two moles of sodium.
2. Only one of the isomers contains a tertiary alcohol group.
3. They all contain a primary alcohol group.

When onions are peeled in air, the reaction shown is thought to occur.



Which tests would give a positive reaction with the organic product?

1. warming with Tollens’ reagent
2. warming with acidified potassium manganate(VII)
3. warming with alkaline aqueous iodine