Centre Number
Candidate Number
Candidate Name
UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE General Certificate of Education Ordinary Level
5070/2
CHEMISTRY PAPER 2 Theory Theor y
MAY/J MAY/JUNE UNE SESSIO SESSION N 200 2001 1
1 hour hour 30 minu minute tes s
Additional materials: Answer paper
TIME
1 hour 30 minutes
INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page and on any separate answer paper used. Section A Answer all questions. Write your answers in the spaces provided on the question paper. pap er. Section B Answer any three questions. Write your answers on the separate answer an swer paper. At the end of the examination, fasten any separate answer paper used securely to the question paper. INFORMATION FOR CANDIDATES The number of marks is given in brackets brackets [ ] at the end of each question or part question. A copy of the Periodic Table Table is printed on page 16. FOR EXAMINER’S USE Section A B9 B10 B11 B12 TOTAL
This question paper consists of 13 printed pages and 3 blank pages. SB (SLC/JB) QF10457/1 © UCLES 2001
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Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 45.
A1 Choose from the following metals to answer the questions below. aluminium
calcium
copper
iron
magnesium
potassium
sodium
zinc
Each metal can be used once, more than once, or not at all. Name a metal which (a) is manufactured by the electrolysis of its molten oxide, ......................................................................................................................................[1] (b) has a variable valency, ......................................................................................................................................[1] (c) is used to galvanise iron, ......................................................................................................................................[1] (d) has a carbonate which is coloured, ......................................................................................................................................[1] (e) is alloyed with zinc to make brass. ......................................................................................................................................[1]
A2 A precipitate may be formed when two aqueous solutions are mixed. Complete the following table. solu soluti tion ons s mix mixed tog toget ethe herr
form ormula ula of prec precip ipit itat ate e formed
colo colour ur of of prec precip ipit itat ate e formed
copper(II) sulphate and sodium hydroxide sodium chloride and silver nitrate potassium iodide and lead(II) nitrate dilute sulphuric acid and barium chloride
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A3 (a) The table shows some information about the oxides of the elements A to E. The letters are not the symbols of the elements. element
state of oxide at room temperature and pressure
type of oxide
bonding in oxide
A
solid
basic
ionic
B
solid
acidic
covalent
C
gas
acidic
covalent
D
liquid
neutral
covalent
E
gas
neutral
covalent
Use
Which one of the elements A to E could be (i)
hydrogen, ...............................................................................................................................[1]
(ii)
sodium, ...............................................................................................................................[1]
(iii)
silicon? ...............................................................................................................................[1]
(b) State the name of an element which forms an amphoteric oxide. ......................................................................................................................................[1]
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A4 Helium-6 and helium-7 are isotopes. The nucleon (mass) number of helium-6 is 6 and of helium-7 is 7. (a) What is the meaning of the term isotopes ? .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[1] (b) Compare the number of electrons, neutrons and protons in one atom of helium-6 and one atom of helium-7. (i)
electrons ...................................................................................................................
(ii)
protons ......................................................................................................................
(iii)
neutrons .................................................................................................................... ...............................................................................................................................[3]
(c) Explain why helium does not react with other elements to form compounds. .......................................................................................................................................... ......................................................................................................................................[1]
A5 Aqueous copper(II) sulphate reacts with aqueous potassium iodide according to the equation below. below. 2Cu2+(aq) + 4I–(aq)
→
2CuI(s) +
I2(s)
(a) Identify the reducing agent in this reaction. Explain your answer. answer. .......................................................................................................................................... ......................................................................................................................................[2] (b) Describe briefly how acidified potassium manganate(VII) can be used to test for a reducing agent. .......................................................................................................................................... ......................................................................................................................................[1]
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A6 Magnesium reacts with chlorine to form the ionic compound magnesium chloride. (a) Draw a ‘dot and cross’ diagram to show the bonding in magnesium chloride. You only need to draw the outer (valence) electrons of o f magnesium and of chlorine.
[2] (b) The physical properties of a compound are related to its structure and bonding. Magnesium chloride has an ionic lattice structure. Suggest two physical properties of magnesium chloride. 1. ...................................................................................................................................... 2. ..................................................................................................................................[2]
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A7 A student investigates the reaction between zinc and dilute hydrochloric acid. The student uses the apparatus shown in the diagram. measuring cylinder
small test-tube held by a piece of cotton
zinc powder water
hydrochloric acid
To start the reaction the student tips the flask so that the acid and zinc can mix. Every minute the student measures the volume of gas collected. The results are plotted on the graph below.
500
400 total volume 300 of hydrogen / hydrogen / 3 cm 200
100
0 0
2
4
6 time / time / minutes minutes 5070/2 Jun01
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10
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(a) Write the equation for the reaction between zinc and dilute hydrochloric acid. ......................................................................................................................................[1] (b) A sample sample of 0.65 g of zinc and 50 cm3 of 2.0 mol/dm mol/dm3 hydrochloric acid is used. Which reagent, zinc or hydrochloric acid, is in excess at the end of the reaction? Explain your answer.
[3] (c) The rate of reaction changes as the reaction proceeds. How and why does the rate of reaction change? .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] (d) The investigation is repeated using exactly the same amounts of zinc and dilute hydrochloric acid. The only difference is that warm hydrochloric acid is used rather than cold hydrochloric acid. On the grid, sketch the graph of the results you would expect. [1]
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A8 The table shows some information about compounds in a homologous series. nam name of comp compou ound nd
mollecul mo ecular ar form ormula ula
rela relati tiv ve molec olecul ular ar mass
boi boiling ling poi point/ °C
methanol
CH3OH
32
65
ethanol
C2H5OH
46
78
propan-1-ol
C3H7OH
60
97
butan-1-ol
C4H9OH
74
117
pentan-1-ol
C5H11OH
88
138
(a) (i)
Name the homologous series to which these compounds belong. ...............................................................................................................................[1]
(ii)
Predict the relative molecular mass of the compound, in the same series, which has seven carbon atoms in one molecule. ...............................................................................................................................[1]
(iii)
Predict the boiling point of hexan-1-ol, which has six carbon atoms in one molecule. ...............................................................................................................................[1]
(iv)
Write the general formula for a compound in this homologous series. ...............................................................................................................................[1]
(b) State a use for ethanol, other than in drinks. ......................................................................................................................................[1]
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(c) Ethanol can be oxidised to form ethanoic acid. (i)
(ii)
Draw the structure of ethanoic acid.
Name a reagent that can be used to oxidise ethanol to ethanoic acid. ...................................................................................................................................
(iii)
Give the name and the structure of the organic product formed when ethanol and ethanoic acid react with each other. name of product ........................................................................................................ structure of product
[4]
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10 Section B Answer three questions from this section. The total mark for this section is 30.
B9 Petrol and diesel are liquid fuels used in the internal intern al combustion engines of motor cars and lorries. (a) Describe how petrol and diesel are obtained from petroleum (crude oil).
[3]
(b) The exhaust gas from an internal combustion engine contains pollutants. The table below shows the mass of pollutants formed when one kilogram of each fuel is burnt. mass of pollutant/g fuel
carbon monoxide
oxides of nitrogen
sulphur dioxide
volatile organic compounds e.g. unburnt hydrocarbons
petrol
236
29
0. 9
25
0.6
diesel
10
59
3.8
17
18.6
(i)
parti rticulates
Which pollutant is a poisonous gas formed by the incomplete combustion of the fuels?
(ii)
Which fuel contributes the most towards acid rain for each kilogram burnt? Explain your answer.
(iii)
Nitrogen dioxide is formed when oxygen reacts with nitrogen. Write the equation for this reaction.
(iv)
Many cars are fitted with catalytic converters. In the catalytic converter carbon monoxide is oxidised and nitrogen dioxide is reduced to form two harmless gases. Suggest the names of these two gases. [5]
(c) Octane, C8H18, is a hydrocarbon found in petrol. Complete combustion of one mole of octane releases 5518 kilojoules of energy. Calculate the energy released on complete combustion of 1.14 g of octane.
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[2]
11 B10 Ethanol is manufactured by the reversible reaction between ethene and a nd steam. C2H4(g) + H2O(g)
CH3CH2OH(g)
The position of equilibrium is affected by changes in pressure and temperature. In an experiment, one mole of ethene was allowed to react with excess steam. The table shows the amount of ethanol in the equilibrium mixture under five different sets of conditions.
(a) (i) (ii)
tempera erature/ °C
pressure/ atm
amoun untt of etha han nol at equilibrium/mol
300 300 300 250 350
50 60 70 50 50
0.40 0.46 0.55 0.42 0.38
Describe the effect of increasing the pressure on the amount of ethanol at equilibrium. Is the reaction between ethene and steam endothermic or exothermic? Explain your answer. answer.
(iii)
Which set of conditions (temperature and a nd pressure) will give the lowest rate of reaction? [4]
(b) Ethene also reacts with hydrogen and bromine. (i) (ii)
Name the product of the reaction between ethene and hydrogen. Draw the structure of the product of the reaction between ethene and bromine. [2]
(c) Ethene forms an addition polymer called poly(ethene). The polymer is used to make plastic bags. Dra Draw th the st struc ructure of and de des scrib ribe a po polllution pr problem caused used by poly oly(ethen ene e).
[2]
(d) Draw a ‘dot and cross’ diagram to show the bonding in a molecule of ethene. You only need to draw the outer electrons of carbon and of hydrogen.
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[2]
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12 B11 There are four stages in the conversion of sulphur into sulphuric acid. • • • •
Stage Stage 1 – Su Sulp lphur hur is burne burned d to to mak make e sul sulph phur ur dio dioxide xide.. Stage Sta ge 2 – Sulphur Sulphur dioxid dioxide e is oxidi oxidised sed to sulph sulphur ur trio trioxid xide e (the (the Contac Contactt Proce Process) ss).. Stage Sta ge 3 – Sulph Sulphur ur trio trioxid xide e is dissol dissolve ved d in sulphur sulphuric ic acid acid to form form oleum oleum.. Stage Sta ge 4 – Oleu Oleum m is is dilu diluted ted with with water water to form form concentr concentrated ated sulphur sulphuric ic acid. acid.
(a) State the catalyst and give the equation for stage 2 (the Contact Process).
[3]
(b) Calculate the mass of sulphur needed to make 196 kg kg of sulphuric acid.
[3]
(c) Give two uses of sulphuric acid.
[2]
(d) Describe what you would see and name the products formed when dilute sulphuric acid reacts with magnesium carbonate. [2]
B12 Chlorine, bromine and iodine are elements in Group VII of the Periodic Table. Table. (a) Describe the trend in colour and physical state at room temperature and pressure as the atomic number increases. [2] (b) Aqueous chlorine is an oxidising agent. (i)
Name the products formed and write an ionic equation for the reaction between aqueous chlorine and aqueous potassium bromide.
(ii)
Name the product formed when aqueous chlorine reacts with aqueous iron(II) chloride. [3]
(c) An oxide oxide of chlorine chlorine was analysed. analysed. A 0.366 g sample was was found found to contain 0.224 0.224 g of oxygen. oxygen. Calculate the empirical formula of this oxide.
[3]
(d) Chlorine (IV) oxide, ClO2, is a powerful oxidising agent. (i) (ii)
Construct an equation to show the decomposition of chlorine(IV) oxide into its elements. Chlorine(IV) oxide reacts explosively with powdered sulphur. Suggest the name or formula of one of the products of the reaction between sulphur and chlorine(IV) oxide. [2]
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