Question
The diagram shows the structures of fi ve compounds, A, B, C, D and E, containing carbon.
(a) Answer these questions using the letters A, B, C, D or E.
Each compound can be used once, more than once or not at all.
Which one of these compounds
(i) is an unsaturated hydrocarbon, …………………………………………………………………
(ii) is a product of the complete combustion of a hydrocarbon, …………………………..
(iii) belongs to the alcohol homologous series, …………………………………………………
(iv) is an alkane, …………………………………………………………………………………………..
(v) is a product of respiration, ………………………………………………………………………..
(vi) is a product of fermentation? …………………………………………………………………….
(b) Write the molecular formula of compound C. …………………………………………………….
(c) Compound B is inert to most chemical reagents.
It is made by reacting chlorine with carbon disulfi de in the presence of an aluminium chloride catalyst.
What do you understand by the following terms?
compound ………………………………………………………………………………………………………….
inert ……………………………………………………………………………………………………………..
catalyst ………………………………………………………………………………………………………..
Answer/Explanation
Answer:
(a) (i) C / \(C_2H_4\) / ethene;
(ii) A / \(CO_2\) / carbon dioxide;
(iii) E / ethanol / correct formula for ethanol;
(iv) D / \(CH_4\) / methane;
(v) A / \(CO_2\) / carbon dioxide;
allow: E
(vi) E / ethanol / correct formula for ethanol;
allow: A
(b) \(C_2H_4\);
(c) compound: substance containing two or more different atoms joined / bonded
together / substance containing 2 or more elements that can only be separated by chemical
means;
allow: different atoms joined / different elements joined / 2 elements react to form a
molecule / molecule with 2 or more elements / substances chemically combined
ignore: two or more molecules combined / different elements react / substances made up of
molecules
reject: if reference to a mixture
inert: unreactive / doesn’t react;
catalyst: substance which speeds up a reaction / it speeds up a reaction;
allow: changes rate of reaction / changes speed of reaction
Question
Hydrogen chloride, HCl, is an acidic gas.
(a) Draw a dot and cross diagram of a molecule of hydrogen chloride.
Show only the outer electrons.
(b) Hydrogen chloride dissolves in water to form a solution of hydrochloric acid.
A student titrated aqueous ammonia with hydrochloric acid using the apparatus shown
below.
(i) State the name of the pieces of apparatus labelled A and B.
A is a
B is a
(ii) Describe how the pH value of the solution in B changes as hydrochloric acid is
added until the acid is in excess.
(iii) Complete the word and symbol equations for this reaction.
ammonia + hydrochloric acid → …………………………………
……….. + HCl → \(NH_4Cl\)
(c) Aqueous ammonia is used to test for copper(II) ions.
Describe what happens when you add aqueous ammonia to a solution of copper(II)
sulfate until the aqueous ammonia is in excess.
Answer/Explanation
Answer:
(a) structure completely correct;;
allow: 1 mark for 1 pair of electrons bonded between H and Cl;
ignore: inner shell electrons
(b) (i) A: burette;
B: flask / erlenmeyer;
(ii) pH starts above 7 / stated value above 7;
allow: high pH
decreases (on addition of acid);
(pH) ends at below 7 / stated value below 7;
allow: low pH
note: pH decreases to pH 7 = 2 marks
note: pH goes from alkali to acid = 1 mark
(iii) ammonium chloride;
reject: ammonia chloride
\(NH_3\);
(c) any 4 of:
blue solution at start /
precipitate formed /
(light) blue (precipitate) /
precipitate redissolves (in excess ammonia) / solution formed (in excess ammonia) /
precipitate disappears
(solution is) deep blue / dark blue
allow: goes deep blue / dark blue / goes darker blue
Question
The reactivity of different metal oxides was compared by heating them with metals in a
crucible.
The results are shown in the table below.
(a) (i) Use the results in the table to suggest the order of reactivity of the metals iron, lead,
magnesium and zinc.
(ii) Predict whether iron will react with zinc oxide.
Explain your answer.
(b) Which two of the following statements about metals are correct?
Tick two boxes.
(c) Sand and salt (sodium chloride) are both solids.
(i) Describe the arrangement and movement of the particles in a solid.
arrangement ………………………………………………………………………………………………..
movement ………………………………………………………………………………………………
(ii) Describe how you could separate the sand from a mixture of sand and salt.
Give full details of how this is carried out.
(d) The diagram below shows the apparatus used to separate ethanol and water from a mixture of ethanol and water.
Complete the following sentences about this separation using words from the list below.
condenser crystallisation distillation flask heavy
higher lower solid volatile vapour
Fractional ……………………… is used to separate a mixture of water and ethanol. The
temperature at the top of the fractionating column is ……………………… than the temperature
at the bottom. The more ……………………… liquid evaporates and moves further up the
column. It eventually reaches the ……………………… where the ……………………… changes
to a liquid.
Answer/Explanation
Answer:
(a) (i) magnesium → zinc → iron → lead / Mg > Zn > Fe > Pb;;
if: one pair reversed / complete order reversed = 1 mark
(ii) no / it will not react and zinc is more reactive / iron is less reactive;
ignore: zinc is reactive / iron is unreactive
(b) 1st box ticked;
last box ticked;
(c) (i) arrangement: regular / fixed pattern / any indication of regularity e.g. in layers;
allow: close together / packed together
ignore: stick together / all together
motion: cannot move / fixed in position/ (only) vibrate;
ignore: only move a little / move
(ii) any three of:
dissolve sodium chloride / add water /
filtration / use a filter paper /
sand remains on filter paper /
ignore: residue on filter paper
salt solution goes through (filter paper) / salt solution is the filtrate / salt water goes into
the collecting tube
allow: decanting for 1 mark (in place of filtration)
ignore: water goes through
ignore: distillation
(d) distillation; lower; volatile; condenser; vapour; (1 mark each)
Question
Lithium has two naturally-occurring isotopes, \(^6_3Li\) and \(^7_3Li\) .
(a) What do you understand by the term isotope?
(b) Draw a labelled diagram to show the atomic structure of an atom of \(^7_3Li\).
Show the particles in the nucleus as well as the electrons.
(c) Lithium reacts with oxygen to form lithium oxide, \(Li_2O\).
Complete the equation for this reaction.
……Li + ……… → ……\(Li_2O\)
(d) Aqueous lithium chloride is electrolysed using the apparatus shown below.
(i) On the diagram above, label:
● the electrolyte
● the anode.
(ii) What do you understand by the term aqueous?
(iii) Explain why aqueous lithium chloride is able to conduct electricity.
Answer/Explanation
Answer:
(a) atoms with same number of protons but different number of neutrons;
allow: atomic number for number of protons
allow: different mass number / nucleon number for different number of neutrons
allow: same (type of) atom with different mass numbers
ignore: atoms with different numbers of neutrons
ignore: element(s) with different numbers of neutrons
ignore: atoms with different relative atomic mass
(b) any 5 of:
nucleus (need not be labelled) in middle of atom and electrons round outside (electrons can
be shown as dots, crosses or e) /
protons in nucleus – labelled or shown by + or p /
3 (protons) /
neutrons in nucleus – labelled or shown by n /
4 (neutrons) /
3 electrons – labelled or shown by dots, crosses or e /
2 electrons in first shell and 1 in second
(c) \(4Li + O_2 → 2Li_2O\) ;;;
allow: two marks for \(2Li + O → Li_2O / 4Li + 2O → 2Li_2O\)
allow: 1 mark for \(O_2\) if no other marks scored
(d) (i) electrolyte correctly labelled;
anode rod correctly labelled;
ignore: label on circuit / label on + sign
(ii) dissolved in water / solution in water;
allow: answers implying substance is mixed with water
ignore: hydrated / hydrous
(iii) ions can move;
allow: ions are free
reject: electrons can move
Question
(a) Match the fuel on the left with the information on the right.
The first one has been done for you.
(b) Two students investigated some fuels to fi nd which gave off the most energy.
They tested four liquid fuels using the apparatus shown below.
(i) In each experiment, the amount of fuel burnt was the same.
Suggest one other factor that should be kept the same in each experiment.
(ii) The students used the thermometer to stir the water.
Suggest why it is important to keep the water stirred.
(iii) The results are shown in the table below.
Which fuel transfers the most energy to the water?
Explain your answer.
(c) Air is needed for fuels to burn.
The pie chart below shows the composition of the air.
State the name of
gas A, ………………………………………………………………………………………………………………..
gas B. ………………………………………………………………………………………………………….
(d) Argon is a noble gas.
(i) State one use for argon.
(ii) To which period in the Periodic Table does argon belong?
(iii) Describe the chemical properties of argon.
Answer/Explanation
Answer:
(a) hydrogen → a fuel with RMM of 2;
methane → the main constituent of natural gas;
fuel oil → fuel for ships;
kerosene → fuel for aircraft;
(b) (i) amount or mass or volume of water / distance of flame from can / height of flame / same
can;
ignore: the water (unqualified) / same amount of fuel / time
(ii) to make sure that the water has the same temperature (throughout) / it is at the same
temperature / so it is heated evenly / so there are no hot spots / so there are no cold
spots;
allow: so that all the particles are heated
ignore: so that particles mix
(iii) petroleum spirit;
highest temperature rise / highest increase in temperature;
allow: calculation of all the temperature differences form the table
ignore: because it releases most heat / because it has the highest temperature
if fuel incorrect = 0 for the question
(c) A = nitrogen / \(N_2\) / N;
B = oxygen / \(O_2\) / O;
(d) (i) lamps / (to provide an) inert atmosphere / in welding / lasers etc
allow: for lighting
ignore: for neon lights
(ii) 3 / third / III;
(iii) inert / unreactive;
ignore: it is stable
Question
A student placed a crystal of silver nitrate and a crystal of potassium iodide in a dish of water.
After an hour she observed that
● the crystals had disappeared,
● a yellow precipitate had appeared near the middle of the dish.
(a) Use your knowledge of the kinetic particle theory and reactions between ions to explain these observations.
(b) Potassium iodide reacts with aqueous chlorine.
Complete the equation for this reaction.
2KI + …….. → ……KCl + \(I_2\)
Answer/Explanation
Answer:
(a) any 4 of:
crystals dissolve or go into solution /
diffusion /
random movement of ions or named particles (can be atoms or ions or particles or
molecules) / particles move everywhere / particles spread out / particles mix
both ions and water in constant movement /
particles collide /
particles react / ions react / atoms react
Ag ions and iodide ions (react) /
(to make) precipitate of silver iodide /
ignore: particles move (unqualified)
(b) \(2KI + Cl_2 → 2KCl + I_2\) ;
allow: 1 mark for 2KI + 2Cl → 2KCl + \(I_2\) ;
Question
The diagram shows one molecule of sulfur.
(a) How many atoms are there in three molecules of sulfur?
(b) Calculate the relative molecular mass of sulfur.
(c) Explain how acid rain is formed when fossil fuels containing sulfur are burnt.
In your answer, include
● the name of a fossil fuel which contains sulfur,
● the gas formed when sulfur burns,
● the reactions which lead to the formation of acid rain.
(d) Potassium sulfate can be used as a fertiliser.
The potassium in this fertiliser is an important element for plant growth.
Name two other elements, important for plant growth, which are present in most
fertilisers.
……………………………………………………. and …………………………………………………….
(e) Describe a test for sulfate ions.
test ……………………………………………………………………………………………………………………
result ……………………………………………………………………………………………………………
Answer/Explanation
Answer:
(a) 24;
(b) 256;
(c) any 4 of:
coal / petroleum / crude oil / named fraction from crude oil
sulfur reacts with oxygen / air
(sulfur burns) to form sulfur dioxide
ignore: sulfur oxide
sulfur dioxide reacts (with gases) in the atmosphere / sulfur dioxide reacts with oxygen /
nitrogen oxides
to form sulfur trioxide
sulfur dioxide / trioxide react with water / rain
allow: sulfur dioxide / trioxide dissolves in water / rain
allow: sulfur oxide(s) mix with water / rain
(to form) sulfurous/ sulfuric acid
(d) nitrogen / N2 / N; phosphorus / P;
(e) add (acidified) barium chloride / barium nitrate;
white precipitate;
note: second mark dependent on correct reagent