chemistry

1 compound x is an organic compound that contains 30.6% carbon, 3.8% hydrogen, 20.4%
oxygen and 45.2% chlorine by mass.
what is the empirical formula of x?
a c2h30cl b  c2h4,oc1 c c3hs,ocl d c,4h302cl2

2 a sample of propane, c3hs, with a mass of 9.61g is completely combusted in an excess of
oxygen under room conditions.
which volume of carbon dioxide gas is produced?
a 4.89dm?* b 5.24dm° c 14.7dm3 d 15.7dm?

3 which atom has the same number of electrons as an ammonium ion?
a mg b na c ne do

4  ethanal reacts with hydroxylamine, nh2oh, to form the molecule shown.
h h
ln a
hoenn
a
h
what is the order of increasing bond angle in this structure from smallest to largest?
a zx y b y,z,x cc xzzy d zy,x

5 descriptions of the bonding in three substances are given.
substance 1. strong covalent bonds between atoms, permanent dipole-dipole
attractions between molecules
substance 2 strong covalent bonds between atoms, weak forces between molecules
substance 3__ strong covalent bonds between atoms, hydrogen bonding between
molecules
which compounds could be substances 1, 2 and 3?
[[-sibstnce 1 | subsance2 | substance 3
a ch30h al2cle¢ ch2cl2
b al2cle ch,cl, ch,
cc ch2cl2 ch, ch30h
d ch, ch30h h,0

6 which type of bonding is never found in elements?
a covalent
bionic
c_ metallic
d_ van der waals’ forces

7 using the information in the table, what is the enthalpy change, gq, for the reaction described?

cs*(g) + br-(g) > csbr(s) ah = qkjmol*

standard value
enthalpy change /kj mol"

ah®,, csbr(s) +25.9

ah? cs*(g) -276

ah, , br-(g) -335

a -636.9 b -585.1 c +585.1 d +636.9

8 which enthalpy change is indicated by x in the enthalpy cycle shown?
c(s) + 2h,(g) + 20,(9)
ah? ch,(g) nero +x
ah¢ ch,(9)
ch,(g) + 20,(g) | ——————+ | co,(g) + 2h,o(1)

a -4-x the enthalpy of combustion of hydrogen
b +4 -x the enthalpy of combustion of hydrogen
c  -2-.x the enthalpy of formation of water

d +2. the enthalpy of formation of water

9 copper dissolves in dilute nitric acid producing a blue solution of cu(nos)2, water and
nitrogen(ii) oxide as the only products.
how many moles of acid react with three moles of copper in the balanced equation?
a 2 b 4 cc 6 d 8

10 nitrogen reacts with hydrogen to produce ammonia.
no(g) + 3h2(g) == 2nhs(g)

a mixture of 2.00 mol of nitrogen, 6.00 mol of hydrogen and 2.40 mol of ammonia is allowed to
reach equilibrium in a sealed vessel of volume 1 dm”. it is found that 2.32 mol of nitrogen were
present in the equilibrium mixture.
which expression will give the value of k,?
a (1.76)?

(2.32)(6.96)°
b (1.76)?

(2.32)(6.32)8
cc (2.08)?

(2.32)(6.32)8
d (2.40)?

(2.32)(6.00)?

11. nitric acid is produced by oxidising ammonia. the first step is to react ammonia with oxygen in
the presence of a catalyst to form nitrogen monoxide.
4nh3(g) + 502(g) == 4no(g) + 6h20(g) ah =-1636kjmol

which set of conditions will produce the greatest yield of nitrogen monoxide at equilibrium?
[| emperatre | pressure |

a high high

b high low

c low high

d low low

12 the height of the peak of the curve in a boltzmann distribution represents the number of
molecules that have the most probable energy.
a sample of gas has its temperature decreased without changing the number of molecules
present.
which statement correctly describes a feature of the boltzmann distribution for the gas when the
temperature decreases?
a_ the value of the most probable energy would stay the same.
b the number of molecules with the most probable energy would increase.
c_ the area under the molecular energy distribution curve would decrease.
d the number of molecules at the very high energy end of the distribution would stay the

same.

13 ammonia exists as simple covalent molecules, nh3. ammonia can react with suitable reagents to
form products containing ammonium ions, nh,”. ammonia can also react with suitable reagents
to form products containing amide ions, nh2 .
which of these nitrogen-containing species are present in an aqueous solution of ammonia?
a ammonia molecules and amide ions
b ammonia molecules and ammonium ions
c ammonia molecules only
d ammonium ions only

14 which problem can result if too much nh4nos is applied to crops by farmers?
a not all the nh,nos; is used by plants and the excess makes the soil alkaline.
b_ rain washes some of the nh,4no; into rivers where it forms a precipitate.
c some of the nh4no; dissolves in groundwater which may eventually be used for drinking.
d ammonia is produced; this lowers the ph of the soil.

15 when descending group 17 from chlorine to iodine, which statement is correct’?
a_ the hydrides become less thermally stable as they become weaker reducing agents.
b_ the hydrides become more thermally stable as the reactivity of the elements decreases.
c_ the volatility of the elements decreases as the van der waals’ forces increase.
d_ the volatility of the elements increases as the size of the molecules increases.

16 a powder is known to be either a single sodium halide or a mixture of two sodium halides.
a sample of the powder was dissolved in water.
aqueous silver nitrate was added, and a pale yellow precipitate was formed. when concentrated
aqueous ammonia was then added, this precipitate partly dissolved leaving a darker yellow
precipitate.
what could the powder be?
a sodium bromide only
b _ sodium iodide only
c  amixture of sodium chloride and sodium bromide
d  amixture of sodium chloride and sodium iodide

1/7 which statement is correct’?
a_ doctors can use the very insoluble mgso, to investigate the digestive system.
b_ farmers can lower the ph of soil by spreading cacos on it.
c students can test a solution for so,” ions by using ba(no3),(aq) followed by hno,(aq).
d_ the insoluble hydroxide, ba(oh)2, can be safely used to lower the acidity of the stomach.

18 asolid, x, was placed in an excess of the liquid y.
a colourless gas was given off and a white precipitate was seen. the precipitate was not x.
what could be the identities of x and y?
x y
a baco3 h20
b ca dilute h»so,
cc mg dilute h2so,
d srco3 dilute hcl

19 two oxides of period 3 elements are added separately to water. both react to form colourless
solutions. one solution is alkaline, the other is acidic.
what could be the two oxides?
a_ ali203 and sioz
b_ ai2,03 and p4019
c nazo and p4019
d na2o and sioz

20 which compound shows stereoisomerism?
a 2-methylbut-2-ene
b= 2-chloropropan-1-ol
c_ difluorochlorobromomethane
d_pent-1-ene

21 two carbon-containing products result from the reaction of alkene z with a hot, concentrated,
acidified solution of potassium manganate(vij).
one product forms an orange precipitate with 2,4-dinitrophenylhydrazine reagent. the other
product is a gas which gives a white precipitate with aqueous calcium hydroxide.
which alkene could be alkene z?
a but-2-ene
b  2-methylpropene
c 2-methylbut-2-ene
d_propene

23 halogenoalkanes react with nucleophiles such as oh’.
which pair of halogenoalkanes both react via an sy1 mechanism?
a b
br cl —
and and “~\nu™

a a br os

cc d

br

— a and a ae a and a a

24 a mixture of ethanol and methanol is burned in oxygen to produce 35cm* of co, and 55cm® of
h20.
complete combustion occurs and the volumes of both products are measured at 101kpa and
120°c.
what is the molar ratio, ethanol: methanol, in the mixture?
a 1:3 b 2:3 c 3:2 d 3:1

25 two reactions are shown. only one product is identified in each reaction.
ethanol + acidified cr20;2 > ethanal
ethanol + sodium — sodium ethoxide
which statement about these reactions is correct?
a the formations of both ethanal and sodium ethoxide are redox reactions.
b_ the formations of both ethanal and sodium ethoxide result in colour changes.
c_ the formation of ethanal is catalysed by potassium dichromate.
d_ the formation of sodium ethoxide is a dehydration reaction.

26 =|he skeletal formulae of three compounds are shown.
r is) il
oh ew ™
—_s a, a,
which compounds will give a positive test with 2,4-dinitrophenylhydrazine reagent?
a ronly b randsonly c sandtonly d r,sandt

27 the diagram shows the structure of a compound formed by the reaction of hcn with a carbonyl
compound, x.
c,h,
a a
on
what is the mechanism of this reaction and what is the functional group in x?
mechanism of reaction functional group in x
a electrophilic addition aldehyde
b electrophilic addition ketone
cc nucleophilic addition aldehyde
d nucleophilic addition ketone

28 compound y is treated with a single reagent under suitable conditions. 2-methylbutanoic acid is
produced.
what could compound y be?
a _pentan-2-one
b  2-methylbutan-2-ol
c 2-methylbutanenitrile
d_ methylpropanenitrile

29 two reactions are shown.
lialh,
(ch,),;chco,h -————* alcohol p
hydrolysis
ch,co,ch(ch,), ———————>_ alcohol q + acid r
to which classes of alcohol do p and q belong?
a primary primary
b primary secondary
cc secondary primary
d secondary secondary

30 the infra-red spectrum of molecule z is shown.
100
transmittance /%
50
0
4000 3000 2000 1500 1000 500
wavenumber/cm-'
what could be the identity of z?
a b
ho oh
0. 0.
ho {j so fo) \ | re)
c d
0. 0.
oo an oy

31 which statements about first ionisation energies are correct?
1 they are always endothermic.
2 they decrease down group 2.
3 they decrease across period 3.

32 the equation shows the decomposition of three moles of an ion containing chromium in an acid
solution.
3cro,> (aq) + 8h*(aq) > 2cro,?(aq) + cr°*(aq) + 4h,o(i)
which statements are correct?
4 one mole of cro,° is reduced.
2 two moles of cro,°* are oxidised.
3 three moles of electrons are transferred.

33 disaccharides are hydrolysed in slightly acidic solutions. this reaction is very slow.
a biological catalyst is added to a slightly acidic mixture of three disaccharides, sucrose, maltose
and lactose. the hydrolysis reaction remains slow for sucrose and maltose but is now much
faster for lactose.
which statements about the catalyst are correct?
1 the catalyst increases the activation energy of all three hydrolysis reactions.
2 the catalyst shows specificity.
3 the hydrolysis of lactose using a catalyst has a different mechanism to the hydrolysis of
lactose without a catalyst.

34 element x is a solid under room conditions. it occurs as a contaminant of fossil fuels.
its oxide, y, is formed when fossil fuels are burned.
in the atmosphere, y can be further oxidised to z.
which statements about x, y and z are correct?
1. atoms of x have paired p electrons.
2 the atmospheric oxidation of y to z is a catalysed reaction.
3 with water, z forms a strong acid.

35 which reagents produce a solution of sodium chlorate(v)?
1 chlorine and hot concentrated sodium hydroxide solution
2 chlorine and cold dilute sodium hydroxide solution
3. chlorine dissolved in water at room temperature

36 which statements help to explain the increase in melting point from sodium to aluminium?
1. the charge on the metal ion increases.
2 there are more delocalised electrons per metal ion.
3. the radius of the metal ion decreases.

37 the diagram shows a molecule of a compound used as a flame retardant.
br
br
br
br br
br
which statements about this structure are correct?
1. each brominated c atom is chiral.
2 the molecular formula is c;z2hobre.
3 the c—c-—c bond angles are all 120°.

38 bromoethane reacts with naoh in different ways depending on the solvent used.
which rows about these reactions are correct?
[| sovent used [erga proauct_|
water ethan-1 ,2-diol
ethanol ethene
water ethanol

39 three compounds, x, y and z, are shown.
x y z
c2hscoch3 c2hscho ch3co2h
which statements about x, y and z are correct?
1 xreacts with alkaline aqueous iodine.
2  y reacts with tollens’ reagent.
3  zdoes not react with alkaline aqueous iodine.

40 5-hydroxypentanoic acid is readily converted into the cyclic compound l.
l
o
o
which statements about this reaction are correct?
1 acidified sodium dichromate(vi) is used as a reagent.
2  awater molecule is produced in the reaction.
3. the reaction can be catalysed by concentrated h2sox,.

Solve 9701_s21_qp_13