ZIMSEC A Level Chemistry Paper 2 November 2000

Question 101

[1 marks]thermochemistry / enthalpy

Dinitrogen pentoxide is formed by the sequence

I $N_2(g) + O_2(g) \rightarrow 2NO(g)$ $\Delta H = +180\ kJ\,mol^{-1}$
II $NO(g) + \frac{1}{2}O_2(g) \rightarrow NO_2(g)$ $\Delta H = -57\ kJ\,mol^{-1}$
III $2NO_2(g) + \frac{1}{2}O_2(g) \rightarrow N_2O_5(g)$ $\Delta H = -55\ kJ\,mol^{-1}$

The enthalpy change of formation of $N_2O_5(g)$ , in $kJ\,mol^{-1}$ , is

A $-44$
B $+11$
C $+68$
D $+121$

Question 102

[1 marks]thermochemistry / enthalpy

The equation corresponding to the standard enthalpy change of formation of dinitrogen pentoxide is

A $2N_2(g) + 5O_2(g) \rightarrow 2N_2O_5(g)$
B $2N(g) + 5O(g) \rightarrow N_2O_5(g)$
C $N_2(g) + O_2(g) \rightarrow N_2O_5(g)$
D $N_2(g) + \frac{5}{2}O_2(g) \rightarrow N_2O_5(g)$

Question 103

[1 marks]thermochemistry / enthalpy

The reaction

N_2(g) + O_2(g) \rightarrow 2NO(g)

is endothermic because

Anitrogen and oxygen are both unreactive gases
Bnitrogen monoxide is a stable molecule
Cthe reaction requires a catalyst
Dthe bonds broken in $N_2$ and $O_2$ are stronger than the bonds formed

Question 104

[2 marks]thermochemistry / enthalpy

State where reaction I,

N_2(g) + O_2(g) \rightarrow 2NO(g)

, occurs both naturally and as a result of human activity. Which pair is correct?

Aforest fires; during the fermentation of sugars
Blightning strikes during thunderstorms; inside the hot cylinders of car engines
Cvolcanic eruptions; during photosynthesis in green plants
Devaporation from the ocean surface; inside refrigeration units

Question 105

[1 marks]thermochemistry / enthalpy

The standard enthalpy change of formation of a compound is the enthalpy change when one mole of the compound is formed from its constituent ___, each in their standard states.

Answer this when you sit the paper.

Question 106

[2 marks]thermochemistry / enthalpy

In the gas-phase structure of dinitrogen pentoxide,

O_2N-O-NO_2

, the shape around each nitrogen atom (bonded to two oxygens directly and one bridging oxygen, with no lone pair) is best described as

Atrigonal planar, with bond angles of about 120 degrees
Blinear, with the three oxygen atoms and the nitrogen atom all in one line
Ctetrahedral, with bond angles of about 109 degrees
Dpyramidal, with a lone pair pushing the three bonds closer together

Question 107

[2 marks]thermochemistry / enthalpy

When dinitrogen pentoxide reacts with water, the product formed is

Anitric acid, $HNO_3$ , only
Bnitrous acid, $HNO_2$ , only
Ca mixture of nitric acid and nitrous acid
Dnitrogen dioxide gas and oxygen gas

Question 201

[1 marks]periodic table / periodicity

The element which can undergo the reduction

XO_2^+(aq) + 2H^+(aq) + e^- \rightarrow XO^{2+}(aq) + H_2O(l)

Question 202

[1 marks]periodic table / periodicity

The element which forms a trifluoride whose molecules are trigonal planar is

Question 203

[1 marks]periodic table / periodicity

The element which has an insoluble chloride is

Question 204

[2 marks]periodic table / periodicity

Of the elements caesium (Cs), sodium (Na), fluorine (F), neon (Ne), lead (Pb) and radon (Rn), which pair correctly gives the element with the lowest first ionisation energy and the element with the highest first ionisation energy, respectively?

Aradon (Rn); caesium (Cs)
Bcaesium (Cs); neon (Ne)
Csodium (Na); radon (Rn)
Dlead (Pb); fluorine (F)

Question 205

[1 marks]periodic table / periodicity

Of the elements fluorine, nitrogen, oxygen and chlorine, the one whose hydride forms the strongest hydrogen bonds is

Anitrogen
Bfluorine
Coxygen
Dchlorine

Question 206

[1 marks]periodic table / periodicity

Give the symbol of an element that forms a nitrate of formula

X(NO_3)_2

which decomposes on heating to give a brown gas.

Answer this when you sit the paper.

Question 207

[1 marks]periodic table / periodicity

Of the ions

Ag^+

Cu^+

Na^+

and

Mg^{2+}

, the monopositive metal ion that readily forms a stable complex ion with ammonia is

A $Ag^+$
B $Mg^{2+}$
C $Cu^+$
D $Na^+$

Question 208

[1 marks]periodic table / periodicity

Of silicon, aluminium, tin and lead, the element whose oxide is the main raw material used to manufacture ordinary sand-based glass and ceramics is

Asilicon
Blead
Caluminium
Dtin

Question 209

[1 marks]periodic table / periodicity

Of caesium, sodium, magnesium and titanium, the element that reacts most exothermically with fluorine gas, per mole of metal, is

Asodium
Bmagnesium
Ctitanium
Dcaesium

Question 301

[1 marks]organic chemistry / combustion

In the apparatus shown,

100\ cm^3

of a mixture of ethane and ethene is passed repeatedly over liquid A, which absorbs only one of the gases. Liquid A is

Adilute sulphuric acid
Bwater
Caqueous bromine
Daqueous sodium chloride

Question 302

[1 marks]organic chemistry / combustion

The equation for the complete combustion of carbon disulphide is

A $CS_2 + O_2 \rightarrow CO_2 + S_2$
B $2CS_2 + 5O_2 \rightarrow 2CO_2 + 4SO$
C $CS_2 + 2O_2 \rightarrow CO_2 + 2S$
D $CS_2 + 3O_2 \rightarrow CO_2 + 2SO_2$

Question 303

[1 marks]organic chemistry / combustion

A mixture containing hydrogen sulphide and carbon disulphide in a 5 : 1 mole ratio is burned in excess oxygen. The

SO_2 : CO_2

mole ratio in the products is

A5 : 1
B6 : 1
C7 : 1
D12 : 1

Question 304

[2 marks]organic chemistry / combustion

Write a balanced equation, including state symbols, for the reaction between liquid A (bromine water) and ethene gas in the mixture.

Answer this when you sit the paper.

Question 305

[2 marks]organic chemistry / combustion

State the formula of the anion formed when

SO_2

dissolves in aqueous NaOH, and the formula of the anion formed when

CO_2

dissolves in aqueous NaOH.

Answer this when you sit the paper.

Question 401

[1 marks]organic chemistry / isomerism

Compound Q contains a

-CHO

group and compound R contains a

-CH_2OH

group. The reagent which distinguishes Q from R is

ATollens' reagent
Baqueous bromine
Cdilute hydrochloric acid
Dsodium metal

Question 402

[1 marks]organic chemistry / isomerism

The isomerism shown about a

C=C

double bond carrying two different groups on each carbon atom is

Astructural
Bcis-trans
Coptical
Dpositional

Question 403

[1 marks]organic chemistry / isomerism

Hot concentrated acidified

KMnO_4

acts on an alkene by

Areducing the $C=C$ bond
Bpolymerising the alkene
Cadding across the $C=C$ bond
Dbreaking the $C=C$ bond

Question 404

[2 marks]organic chemistry / isomerism

Compound R contains a functional group that is absent from both P and Q. This functional group, together with the observation made when R is treated with sodium metal, is

Aa carboxylic acid (-COOH) group; effervescence of a colourless gas (carbon dioxide)
Ban ether (C-O-C) linkage; no visible reaction at all
Ca hydroxyl (-OH) group; effervescence of a colourless gas (hydrogen)
Da carbonyl (C=O) group; a colour change from orange to green

Question 405

[2 marks]organic chemistry / isomerism

Hydrogenating P, Q and R separately, then oxidising each product under reflux with excess acidified potassium dichromate(VI), gives the same organic product in every case because

Ahydrogenation converts all three terminal groups directly into the same carboxylic acid before oxidation even begins
Bhydrogenation removes every C=C bond to leave the same saturated carbon skeleton in all three, and reflux with excess oxidising agent then oxidises both the -CHO of P and Q and the -CH2OH of R fully to the same -COOH group
Cacidified dichromate(VI) first breaks each carbon skeleton apart, so only the smallest common fragment survives in every case
DP, Q and R are actually the same compound, so hydrogenation and oxidation cannot give different products

Question 406

[1 marks]organic chemistry / isomerism

When compound Q, which contains a

-CHO

group, is warmed with Fehling's solution, a colour change to a brick-red precipitate of ___ is observed.

Answer this when you sit the paper.

Question 501

[1 marks]chlorine chemistry / environmental chemistry

Sodium chlorate(I), NaOCl, is used as a household bleach and disinfectant because it is

Aa strong oxidising agent
Ba weak base
Ca strong acid
Da strong reducing agent

Question 502

[1 marks]chlorine chemistry / environmental chemistry

A problem which arises when waste PVC is burned is that

Acarbon dioxide is released
Bchlorine dissolves in ground water
Ca hard insoluble ash is formed
Dtoxic hydrogen chloride and dioxins are produced

Question 503

[1 marks]chlorine chemistry / environmental chemistry

Chlorofluorocarbons released into the atmosphere are harmful because they

Acause acid rain
Bdeplete the ozone layer
Cdissolve in ground water
Dform photochemical smog

Question 504

[2 marks]chlorine chemistry / environmental chemistry

PVC (poly(chloroethene)) is widely used to make water pipes and electrical cable insulation mainly because it is

Abiodegradable, so old pipes break down harmlessly in landfill
Ba good electrical conductor, carrying current safely alongside the cable's copper wire
Cdurable, waterproof and an effective electrical insulator
Dhighly reactive, forming a protective oxide layer like some metals

Question 505

[2 marks]chlorine chemistry / environmental chemistry

Beyond the toxic gases released when chlorinated plastics such as PVC are burned, a further environmental problem with disposing of them in landfill is that they

Areact with atmospheric oxygen to reform the original monomer over time
Bgenerate enough heat through slow oxidation to start underground fires
Cpersist largely un-degraded for a very long time, since micro-organisms cannot readily break the strong C-Cl bonds
Ddissolve slowly in rainwater, releasing free chlorine gas into the soil

Chemistry Paper 2 November 2000

Sit this paper online

The questions

Question 101

Question 102

Question 103

Question 104

Question 105

Question 106

Question 107

Question 201

Question 202

Question 203

Question 204

Question 205

Question 206

Question 207

Question 208

Question 209

Question 301

Question 302

Question 303

Question 304

Question 305

Question 401

Question 402

Question 403

Question 404

Question 405

Question 406

Question 501

Question 502

Question 503

Question 504

Question 505

More sittings of this paper

The answers, and why they are the answers

Sit this paper online