Question
Petroleum is a useful natural resource.
The diagram shows how petroleum can be separated into useful substances.
(a) What is the name of the separation process shown in the diagram?
(b) Name the fraction leaving at:
A ………………………………………………………………………………………………………………………………
B ………………………………………………………………………………………………………………………………
(c) Refinery gas is a mixture of hydrocarbons.
One refinery gas is butane, \(C_4H_{10}\).
(i) Suggest the names of two other refinery gases.
……………………………………………………… and ……………………………………………………..
(ii) Write the chemical equation for the complete combustion of butane.
(iii) Name the toxic gas produced by the incomplete combustion of butane.
(d) Gasoline and kerosene are both fuels. They have different properties.
(i) Describe the differences in the properties given.
viscosity of the fuel ……………………………………………………………………………………………….
flammability of the fuel …………………………………………………………………………………………..
(ii) What difference in the molecules of gasoline and kerosene causes these differences in
properties?
(e) Hydrogen fuel cells can be used to power vehicles.
Write the word equation for the overall reaction that takes place in a hydrogen fuel cell.
Answer/Explanation
Answer:
(a) distillation (1)
fractional (1)
(b) naphtha (1)
bitumen (1)
(c) (i) any two from:
methane ethane propane
(ii) \(2C_4H_{10} + 13O_2 \rightarrow 8CO_2 + 10H_2O\)
\(CO_2\) and \(H_2O\) as products (1) correct equation (1)
(iii) carbon monoxide
(d) (i) kerosene is more viscous
gasoline is more flammable
(ii) kerosene has molecules with a longer carbon chain
(e) hydrogen + oxygen \(\rightarrow \) water
Question
Aluminium is extracted from its ore. The ore is converted into pure aluminium oxide, which then
undergoes electrolysis as shown.
(a) (i) Name an ore of aluminium.
(ii) What is meant by the term electrolysis?
(b) Aluminium oxide has a melting point of about 2000°C, but the electrolysis process operates at
about 900°C.
(i) Name the compound added to aluminium oxide to reduce the operating temperature.
(ii) Suggest one benefit to the environment of reducing the operating temperature.
(iii) Write the ionic half-equation for the reaction taking place at:
the negative electrode (cathode) …………………………………………………………………………….
the positive electrode (anode) ………………………………………………………………………………..
(iv) Explain why the anodes need frequent replacement.
(c) Aluminium oxide reacts with acids and with alkalis.
(i) What term is used to describe an oxide that reacts with acids and with alkalis?
(ii) Aluminium oxide reacts with dilute sulfuric acid to form a salt.
State the name and write the formula of the salt formed.
name …………………………………………………………………………………………………………………..
formula ………………………………………………………………………………………………………………..
(iii) Aluminium oxide reacts with dilute sodium hydroxide to form a salt and one other product.
Name the other product.
(iv) Aluminium hydroxide, \(Al(OH)_3\), decomposes when heated to form aluminium oxide and
water.
Write the chemical equation for this reaction.
(v) Suggest the names of two other aluminium compounds that decompose when heated to
form aluminium oxide.
Answer/Explanation
Answer:
(a) (i) bauxite
(ii) breakdown by (the passage of) electricity (1)
of an ionic compound in molten / aqueous (state) (1)
(b) (i) cryolite
(ii) less \(CO_2\) emission
(iii) \(Al^{3+} + 3e^- \rightarrow Al\)
any positive Al species gainig electron(s) (1)
correct species and balance (1)
\(2O^{2–} \rightarrow O_2 + 4e^–\)
any negative O species losing electron(s) (1)
correct species and balance (1)
(iv) anodes or carbon / graphite react with oxygen / \(O_2\) (1)
(form) carbon dioxide (1)
(c) (i) amphoteric
(ii) aluminium sulfate (1) \(Al_2(SO_4)_3\) (1)
(iii) water
(iv) \(2Al(OH)_3 \rightarrow Al_2O_3 + 3H_2O\)
species (1) balance (1)
(v) aluminium carbonate (1)
aluminium nitrate (1)
Question
The Periodic Table is a method of classifying elements.
(a) Identify the element which is in Group VI and Period 4.
(b) Calcium is in Group II and chlorine is in Group VII of the Periodic Table.
Explain, in terms of number of outer shell electrons and electron transfer, how calcium atoms
and chlorine atoms form ions. Give the formulae of the ions formed.
(c) Group V chlorides are covalent molecules. The boiling points of some Group V chlorides are
shown.
(i) Suggest the approximate boiling point of \(PCl_3\).
(ii) Explain the trend in boiling points in terms of attractive forces between particles.
(iii) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of
\(PCl_3\).
Show outer electrons only.
(d) PCl 3 reacts with chlorine, Cl2, to form PCl 5. This reaction is exothermic and reaches an
equilibrium.
\(PCl_3(g) + Cl_2(g) \leftrightarrow PCl_5(g)\)
(i) Describe two features of an equilibrium.
(ii) State the effect, if any, on the position of this equilibrium when the following changes are
made.
Explain your answers.
temperature is increased ……………………………………………………………………………………….
pressure is increased ……………………………………………………………………………………………
(iii) Explain, in terms of particles, what happens to the rate of the forward reaction when the
reaction mixture is heated.
(e) \(PCl_5\) reacts with lithium fluoride, LiF, to form \(LiPF_6\).
\(PCl_5 + 6LiF → LiPF_6 + 5LiCl\)
Calculate the mass of LiF needed to form 3.04g of \(LiPF_6\) using the following steps.
● Calculate the number of moles of LiPF6 formed.
[Mr : \(LiPF_6\), 152]
number of moles = …………………………
● Deduce the number of moles of LiF needed.
number of moles = …………………………
● Calculate the mass of LiF needed.
mass = ………………………… g
(f) Lithium fluoride has ionic bonding.
(i) What is an ionic bond?
(ii) Give two physical properties of ionic compounds.
Answer/Explanation
Answer:
(a) selenium / Se
(b) Ca has 2 and Cl has outer electrons 7 (1)
Ca (atoms) lose electrons (1)
Cl (atoms) gain electrons (1)
\(Ca^{2+}\) (ions) (1)
\(Cl^–\) (ions) (1)
(c) (i) any number in the range 72 – 129°C
(ii) 3 P- Cl dot cross bonds (1)
2 (only) non-bonding electrons to make an octet on P (1)
6 (only) non-bonding electrons to make an octet on each Cl (1)
(d) (i)
constant concentrations (1)
rate of forward reaction
= rate of reverse reaction (1)
(ii) increased temperature:
(equilibrium) shifts to LHS (1)
(forward) reaction is exothermic (1)
increased pressure:
(equilibrium) shifts to RHS (1)
fewer moles (of gas) on RHS (1)
(iii) rate increases and particles have more energy (1)
more collisions (between particles) occur per second / per unit time
more (of the) particles / collisions have energy greater than activation energy
or
more (of the) particles / collisions have sufficient energy to react
or
a greater percentage / proportion / fraction of collisions (of particles) are successful
(e) mol of LiPF6 = 3.04 / 152 = 0.02(00) (1)
mol of LiF = 0.02(00) × 6 = 0.12(0) (1)
mass of LiF = 3.12 g (1)
(f) (i) oppositely charged ions
(ions) are attracted
(ii) any two from:
physical constants: high boiling point / melting point
conductivity: conduct (electricity) when aqueous or conduct (electricity) when molten
solubility: soluble in water
Question
Iron is a typical transition element.
Iron:
● acts as a catalyst
● forms coloured compounds
● has more than one oxidation state.
(a) Name one major industrial process that uses iron as a catalyst and name the product made in
this process.
process ……………………………………………………………………………………………………………………..
product made ……………………………………………………………………………………………………………..
(b) When aqueous sodium hydroxide is added to aqueous iron(II) sulfate, a precipitate forms.
(i) What colour is this precipitate?
(ii) Write the ionic equation for this reaction. Include state symbols.
(c) Iron(II) sulfate can be converted to iron(III) sulfate by potassium manganate(VII) at room
temperature.
(i) What is the role of potassium manganate(VII) in this reaction?
(ii) What condition must be used for this reaction to occur?
(iii) In terms of electron transfer, what happens to the iron(II) ions in this reaction?
(iv) State the colour change seen during this reaction.
from purple to …………………………………………………………………………………………………
(d) Deduce the charge on the iron ion in each of these compounds.
\(FeF_3\) ………………………………………………………………………………………………………………………….
\(Fe(NO_3)_3\) ……………………………………………………………………………………………………………………
Answer/Explanation
Answer:
(a) Haber (process) (1)
ammonia (1)
(b) (i) green
(ii) \(Fe^{2+}(aq) + 2OH^–(aq) \rightarrow Fe(OH)_2(s)\)
\(Fe(OH)_2\) (as only product) (1)
\(Fe^{2+}\) and \(2OH^–\) (as reactants) (1)
state symbols (1)
(c) (i) oxidising agent
(ii) presence of an acid
(iii) lose an electron
(iv) colourless
(d) 3+
3+
Question
There are two types of polymers.
(a) Addition polymers are made from many identical small units.
(i) What is the term used to describe these small units?
(ii) A section of an addition polymer is shown.
Draw the structure of the small unit used to make this addition polymer.
Show all of the atoms and all of the bonds.
(b) Polyamides are condensation polymers.
What does the term condensation mean when used to describe this type of polymer?
(c) A polyamide can be made from two different molecules.
A simplified structure of octanedioic acid is shown.
A simplified structure of 1,6-diaminohexane is shown.
(i) Complete the diagram to show a section of polyamide manufactured from octanedioic acid
and 1,6-diaminohexane. Include all of the atoms and all of the bonds in the linkages. 
(ii) State the name of a synthetic polyamide.
Answer/Explanation
Answer:
(a) (i) monomer
(ii)
any hydrocarbon with one C=C bond (with both C atoms having 4 bonds) (1)
structure of methylpropene (1)
(b) water is a product (when polymer is made)
(c) (i)
any correct amide link between any two blocks showing all atoms and all bonds (1)
correct orientation of 3 inter-block amide links (1)
continuation bonds (1)
(ii) nylon