Question
(a) The electronic structures of five atoms, A, B, C, D and E, are shown.
Answer the following questions about these electronic structures.
Each electronic structure may be used once, more than once or not at all.
State which electronic structure, A, B, C, D and E, represents:
(i) an atom in Group V of the Periodic Table.[1]
(ii) an atom which contains only two shells of electrons.[1]
(iii) an atom that forms a stable ion with a charge of 2–.[1]
(iv) an atom of an element that exists as a monoatomic gas.[1]
(v) an atom of the metal that is extracted from bauxite.[1]
(b) Complete the table to show the number of electrons, neutrons and protons in the uranium atom and rubidium ion shown.
Answer/Explanation
Ans:
(a)(i) A
(a)(ii) C
(a)(iii) C
(a)(iv) B
(a)(v) D
(b) number of electrons in Rb ion: = 36 (1)
number of neutrons in U = 143 (1)
number of protons in U = 92
AND
number of protons in Rb ion = 37 (1)
Question
(a) Biogas is a mixture of gases produced when agricultural waste is broken down in the absence of oxygen.
The table compares the percentage by mass of the gases present in two samples of biogas, X and Y.
Answer these questions using only the information in the table.
(i) Deduce the percentage by mass of the other gases in biogas X.[1]
(ii) Describe two major differences in the compositions of biogas X and biogas Y.[2]
1
2
(b) Complete the diagram to show the electronic structure in a methane molecule.
Show only the outer shell electrons.[1]
(c) Hydrogen sulfide burns in air to produce sulfur dioxide and water.
(i) Complete the chemical equation for this reaction.
…..H2S + …..O2 → 2H2O + 2SO2 [2]
(ii) Explain how this equation shows that hydrogen sulfide is oxidized.[1] [Total: 7]
Answer/Explanation
Ans:
(a)(i) 1 (%)
(a)(ii) 1 mark each for any two of:
- less carbon dioxide in X / more carbon dioxide in Y
- more methane in X / less methane in Y
- less nitrogen in X / more nitrogen in Y
(b) 2 electrons in each of the four overlap areas
AND
no unpaired electrons on the hydrogen atoms
(c)(i) 2 (H2S) (1)
3 (O2) (1)
(c)(ii) sulfur has gained oxygen / hydrogen sulfide has gained oxygen
Question
This question is about metals.
(a) State three general physical properties common to most metals.[3]
1
2
3
(b) Metals are often used in the form of alloys.
(i) State the meaning of the term alloy.[1]
(ii) Explain in terms of their properties why alloys are used instead of pure metals.[1]
(iii) Stainless steel is an alloy.
Give one use of stainless steel.[1]
(c) Place these metals in order of their reactivity with oxygen.
copper
magnesium
potassium
zinc
Put the least reactive metal first.[2]
(d) When 4.8g of magnesium reacts with excess oxygen, 8.0g of magnesium oxide is formed.
Calculate the minimum mass of magnesium needed to produce 24.0g of magnesium oxide.
minimum mass = g [1] [Total: 9]
Answer/Explanation
Ans:
a) 1 mark each for any three of:
- conduct electricity / conduct heat
- malleable
- ductile
- shiny / lustrous
- sonorous / rings when hit
(b)(i) mixture of metal with another element
(b)(ii) (alloy is) hard(er) / (more) resistant to corrosion / strong(er)
(b)(iii) cutlery / chemical plant / surgical equipment
(c) copper , zinc , magnesium , potassium (2)
if 2 marks not scored: 1 mark for one consecutive pair reversed
(d) 14.4 (g)
Question
This question is about acids, bases and salts.
(a) Sodium hydroxide is a base.
(i) Name the products formed when sodium hydroxide reacts with dilute nitric acid.[2]
(ii) Describe the effect of sodium hydroxide on a named indicator.[2]
(iii) Complete the word equation for the reaction of sodium hydroxide with ammonium chloride.
(b) Describe how to prepare pure, dry crystals of the salt zinc sulfate from an aqueous solution of zinc sulfate.[2]
(c) The rate of reaction of zinc powder with dilute sulfuric acid is found by measuring the increase in volume of hydrogen gas produced as time increases.
Describe the effect, if any, of each of the following on the rate of this reaction.
- The reaction is carried out with large pieces of zinc instead of zinc powder.
All other conditions stay the same.
- The reaction is carried out using a catalyst.
All other conditions stay the same.
- The reaction is carried out with dilute sulfuric acid of a lower concentration.
All other conditions stay the same. [3] [Total: 11]
Answer/Explanation
Ans:
(a)(i) sodium nitrate (1)
(and) water (1)
(a)(ii) named suitable indicator e.g. methyl orange / litmus (1)
correct colour in alkali e.g. blue (for litmus) / yellow (for methyl orange) (1)
(a)(iii) ammonia (1)
sodium chloride (1)
(b) 1 mark each for any two of:
- evaporate to point of crystallisation / heat to point of crystallisation / evaporate some of the water and leave (1)
- filter crystals / pick out crystals (1)
- dry with filter paper / dry in drying oven
(c) large pieces: (rate) decreases / (reaction gets) slower (1)
catalyst: (rate) increases / (reaction gets) faster (1)
lower concentration: (rate) decreases / (reaction gets) slower (1)
Question
This question is about air.
(a) The pie chart shows the proportions of the main gases in clean, dry air.
(i) Name the gases G and H.[2]
gas G
gas H
(ii) The graph shows how the volume of a sample of gas G changes as temperature increases. The pressure is kept constant.
Describe how the volume of gas G changes as temperature increases.[1]
(iii) There is a small percentage of noble gases in the air.
The noble gases are unreactive.
Explain why the noble gases are unreactive in terms of their electronic structure.[1]
(iv) Describe the arrangement and separation of the particles in a gas.[2]
arrangement
separation
(b) Two of the pollutants in air are oxides of nitrogen and lead compounds.
(i) Give one effect of each of these pollutants on health.[2]
oxides of nitrogen
lead compounds
(ii) Name two other pollutants present in air.
State the source of each of these pollutants.[4]
pollutant 1
source of pollutant 1
pollutant 2
source of pollutant 2 [Total: 12]
Answer/Explanation
Ans:
(a)(i) G is oxygen (1)
H is nitrogen (1)
(a)(ii) volume increases (as temperature increases)
(a)(iii) they have a full outer shell (of electrons) / they have a complete outer shell (of electrons)
(a)(iv) arrangement: irregular / random (1)
separation: far apart (1)
(b)(i) oxides of nitrogen:
breathing difficulties / irritates lungs / irritates eyes / irritates throat / irritates skin / lung problems (1)
lead compounds:
poisonous / toxic / harms nervous system / harms brain (1)
(b)(ii) 1 mark for each correct pollutant and one 1 mark for each correct source e.g.
sulfur dioxide (1)
burning fossil fuels / volcanoes (1)
carbon monoxide (1)
incomplete combustion of carbon containing substance / incomplete combustion of named carbon compound (1)
Question
The table shows some properties of four Group I elements.
(a) (i) Complete the table by estimating:
- the boiling point of sodium
- the relative hardness of lithium. [2]
(ii) Predict the physical state of lithium at 200°C.
Give a reason for your answer. [2]
(b) Potassium reacts with water.
2K + 2H2O → 2KOH + H2
Describe two observations when potassium reacts with water.[2]
1
2
(c) Lithium is extracted by the electrolysis of molten lithium chloride.
(i) Name a non-metal used to make the electrodes.[1]
(ii) Give one property, other than the conduction of electricity, that makes this substance suitable for use as an electrode.[1]
(iii) State the products of the electrolysis of molten lithium chloride at:[2]
the negative electrode (cathode)
the positive electrode (anode)
(d) Lithium chloride conducts electricity when molten and when in aqueous solution.
Give two other physical properties of lithium chloride that show it is an ionic compound.[2]
1
2 [Total: 12]
Answer/Explanation
Ans:
(a)(i) boiling point of Na any values between 800 and 1300 (°C) (inclusive of these values) (1)
hardness of Li: any value above 0.70 (MPa) up to a maximum of 5.0 (MPa) (1)
(a)(ii) liquid (1)
200 °C is above the melting point and below the boiling point / 200 °C is between the melting and boiling points (1)
(b) 1 mark each for any 2 of:
- bubbles / effervescence / fizzing
- potassium disappears
- potassium moves around
- potassium floats on the surface
- (bursts into) flame / sparks / explodes
BUT
colour of flame is lilac = 2 marks
(c)(i) carbon / graphite
(c)(ii) inert / unreactive
(c)(iii) negative electrode: lithium (1)
positive electrode: chlorine (1)
(d) high boiling point / high melting point (1)
soluble in water (1)
Question
(a) The structures of four organic compounds, P, Q, R and S, are shown.
Answer the following questions about these structures.
Each structure may be used once, more than once or not at all.
(i) State which structure, P, Q, R or S, has a carboxylic acid functional group.[1]
(ii) State which structure, P, Q, R or S, is in the same homologous series as ethane.[1]
(iii) State which structure, P, Q, R or S, decolourises aqueous bromine.[1]
(iv) Deduce the molecular formula of structure Q to show the number of carbon, hydrogen and oxygen atoms.[1]
(b) Structure S is produced by cracking petroleum fractions.
(i) Complete the sentence using a word from the list.
acids alkenes alcohols nitrogen
During cracking, long-chain alkanes are converted to shorter chain alkanes and[1]
(ii) Cracking is an example of thermal decomposition.
State the meaning of the term thermal decomposition.[2]
(c) Link each petroleum fraction on the left to its use on the right.
The first one has been done for you.
Answer/Explanation
Ans:
(a)(i) Q
(a)(ii) S
(a)(iii) R
(a)(iv) C4H8O2
(b)(i) alkenes
(b)(ii) breakdown of a compound (1)
using heat / by heat (1)
(c) naphtha → making chemicals
lubricating fraction → waxes and polishes
kerosene → jet fuel
all 3 correct (2)
1 or 2 correct (1)
Question
This question is about chlorine and compounds of chlorine.
(a) Chlorine is an element in Group VII of the Periodic Table.
State the meaning of the term element.[1]
(b) State one use of chlorine.[1]
(c) Chlorine reacts with phosphorus to produce phosphorus(V) chloride.
(i) Balance the equation for this reaction.
…..P + …..Cl2 → 2PCl5 [2]
(ii) This reaction is exothermic.
State the meaning of the term exothermic.[1]
(d) Chlorine reacts with aqueous sodium bromide.
(i) Complete the word equation for this reaction.
(ii) Describe a test for bromide ions.[2]
test
observations
(iii) When bromine is mixed with aqueous sodium chloride there is no reaction.
Suggest in terms of chemical reactivity why there is no reaction.[1]
(e) A compound of chlorine has the formula C3H6Cl2.
Complete the table to calculate the relative molecular mass of C3H6Cl2.
relative molecular mass = [2] [Total: 12]
Answer/Explanation
Ans:
(a) substance containing only one type of atom / substance where the atoms have the same proton number
(b) water treatment / water purification / killing bacteria
c)(i) 2 (P) (1)
5 (Cl2) (1)
c)(ii) releases thermal energy / releases heat
(d)(i) bromine (1)
sodium chloride (1)
(d)(ii) (add nitric acid and aqueous) silver nitrate (1)
cream precipitate / cream solid (1)
(d)(iii) bromine is less reactive than chlorine / chlorine more reactive than bromine 1
(e) 113 (2)
If two marks not scored, allow 1 mark for H = 6 × 1 / 6 OR Cl = 2 × 35.5 / 71