Centre Number Candidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITYOF CAMBRIDGE LOCAL EXAMINATIONSSYNDICATE CHEMISTRY PAPER 3 0620/3 Thursday 9 NOVEMBER 2000 Morning 1 hour 15 minutes Candidates answer on the question paper. Additional materials: Electronic calculator and/or Mathematical tables TIME 1 hour 15 minutes INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer all questions. Write your answers in the spaces provided on the question paper. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. Mathematical tables are available. You may use a calculator. A copy of the Periodic Table is printed on page 12. This question paper consists of 10 printed pages and 2 blank pages. S8 (SLCfTC) OK07569/2 @ UCLES 2000 [Turn over FOR EXAMINER'S USE 1 2 3 4 5 TOTAL
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Centre NumberCandidateNumber
Candidate Name
International General Certificate of Secondary EducationUNIVERSITYOF CAMBRIDGE LOCAL EXAMINATIONSSYNDICATE
CHEMISTRYPAPER3
0620/3
Thursday 9 NOVEMBER 2000 Morning 1 hour 15 minutes
Candidates answer on the question paper.Additional materials:
Electronic calculator and/or Mathematical tables
TIME 1 hour 15 minutes
INSTRUCTIONS TO CANDIDATES
Write your name, Centre number and candidate number in the spaces at the top of this page.
Answer all questions.
Write your answers in the spaces provided on the question paper.
INFORMATION FOR CANDIDATES
The number of marks is given in brackets [ ] at the end of each question or part question.Mathematical tables are available.
You may use a calculator.
A copy of the Periodic Table is printed on page 12.
This question paper consists of 10 printed pages and 2 blank pages.
S8 (SLCfTC) OK07569/2@UCLES 2000 [Turn over
FOR EXAMINER'S USE
1
2
3
4
5
TOTAL
1 The element scandium, proton (atomic) number, Z = 21, was discovered by L Nilson inSweden in 1879.
(a) It forms only one ion which has the formula ~fSC3+.
(i) How many electrons, protons and neutrons are there in this ion?
number of electrons l.~ """""""""""""""'"
number of protons :;?...I.................................................................................
number of neutrons g.4 oo oo..........
(ii) Predict the electron distribution of this ion.-=:z.
(iii) An alternative method of extracting scandium is by the electrolysis of a moltenmixture that contains scandium chloride. Write ionic equations for the reactions atthe electrodes.
S 3+- + 3 - ~ Screaction at cathode ..C ~t)... e :: .C.~) .oooo..oooo...I
reaction at anode Q.CJ...::-{L~ ~.. ..C!. 'k .(j-} ..+...2e..::: [2J I
(c) The density of scandium is 2.99 g/cm3 and it has only one valency of three. Scandiumcompounds are white solids and form colourless solutions. Titanium is a more typicaltransition metal, predict how its properties would be different from those of scandium.
(ii) A diagram of the structure of poly(ethene) is given below.
'~
H H
I IC-C
I IH H
Draw a similar diagram to show the structure of poly(propene).
CH 3 H-
I ,
C-c
1. 1
H H
[3]
~
Examiner's
(b) (i) Ironfrom the blast furnace is impure. It containsabout5% of carbon and of other I Useimpurities such as silicon and sulphur. Describe how this impure iron is convertedinto mild steel. BA~Ic. OX'ft1£N S"T'£.E:.I- Mi\"KtNi( PR..OCe.~
(c) Two of the chemicals used to make concrete are limestone and sand. Limestone is anionic compound, containing the ions Ca2+andCO32-. Sand is mainly an oxide of siliconwhich is macromolecular.
/' Coc;:. -rCO ]) L.c ~ r h..,- To t1Ati'J 01<-~ E.. lJ-es '\L' (rT\.\""'" 'tr620/3NovOO [turn o~
.b IN
roc
3 Organic compounds that contain the halogens can have chloro, bromo or iodo in their names.
(a) The following diagram shows the structure of 1-bromobutane.
H H H H
I I I I
H-C-C-C-C-Br
I I I I
H H H H
Q
c'
~.
(i) Draw the structure of an isomer of this compound.
f-/ \4 B( I-J.
I I , r
H- C -C-C-C-H. , r I 1
H H H H(ii) Draw a possible structure of a dibromobutane.
e'3.t-\ (4 )-\ B~, , , '
H-C- c-c- (,-8...-\ , , ,H r\ ~ \1
t>r
S E'-fe. .<A'z..- ftI2£POSSl ~ \..E.
Bl" J+ ~ Br\ J , T
t\-e,-C-C- c:-141 \ , \H- H J.4. \..\
(iii) Name two chemicals that react together to make only one product -dibromobutane.
..&..lr..E;;...N'.~ and ...1:$.~. ~.~.. ...........................[4]
(b) Draw a diagram to show the arrangement of the valency electrons in the covalentcompound chloromethane.Use 0 to represent an electron from carbonUse x to represent an electron from hydrogenUse <8>to represent an electron from chlorine
CH3Ct
";'
[3]
(c) Organic halides react with water to form an alcohol and a halide ion.The halogen present in an organic compound can be determined by identifying thehalide ion.
Use
CH3CH2Br + H2O ~ CH3CH2OH + H+ + Br-bromoethane + water ethanol bromide ion
(i) Name the alcohol formed when 1-bromobutane reacts with water.
(ii) Describe how you could test for the bromide ion.
reagent used. ...C.ij.~ ~.~.t;.....~ " ....
result of test ...9..~§/9g~ c.~ ~ ~~2..{aI\')"""""""""'"
(iii) Suggest an explanation for the following observations.Bromine was bubbled through a solution containing a halide ion. The solutionturned dark brown.
The rate of reaction between an organi9 halide and water can be studied in the followingexperiment.
A mixture of 10cm3 of aqueous silver nitrate and 10cm3 of ethanol are warmed to60 DC.Drops of the organic halide are added and the time taken for a precipitate to formis measured.
The reaction produces halide ions which react with the silver nitrate to give a precipitateof a silver halide. The results are given in the table.
~
(i) Write the three organic halides in order of reactivity with water.
iQ.~<?.~n~ most reactive
b~9..ku:mtl.~.. tc:hloy'Q.buJ~~e least reactive
. (ii) ~B.~i.n.~;~O~~O.d.b.;;:t:~~ 7~r~e~~;'.in..~:.......c~.~~ tban A ...SO ~.. ..ce.~~9A ...
[3][Turnover
,IS ~\er (V\. "& 0620/3 NovOO
experiment organic halide number of drops time/min..
A bromobutane 4 5
B bromobutane 8 2
C chlorobutane 4 100
D iodobutane 4 0.1
4 The two non-metals, sulphur and selenium, are in Group VI.
(a) Sulphuric acid is made from sulphur. This acid is used to make detergents calledsulphonates. A hydrocarbon is made to react with oleum (fuming sulphuric acid) to formsulphonic acids. These form salts called sulphonates.
(i) Complete the word equations for some reactions of a sulphonic acid.
(iv) How is oleum changed into concer'ttratedsulphuric acid?
0 ...oleMt{\oo...ls dl.\.~d w.ith W~oo .oo ,.[7]
(b) Insoluble and soluble sulphates can each be made from dilute sulphuric acid. Describehow a pure sample of the insoluble salt, lead(II) sulphate, can be made.
(d) Selenium is used to make a device that can change light energy into electrical energy.
(i) Name the process used in green plants to change light energy into chemical energy.
p.~$~.0.fu~~.§................................................................................(ii) Explain how a liquid fuel can be obtained from plant material.
Chemistry is concerned with problem-solving and answering questions. For each of the' Usefollowing,describe any experiments that are needed and, when necessary, indicate how theresults should be used to solve the problem.
(a) Nickel sulphate-7-water exists as bright green crystals and anhydrous nickel sulphateas a yellowpowder. How could you show that the action of heat on the hydrated salt is areversible reaction?
(d) The formula of an acid is either of the type HY or H2Y. How could you find out which oneis correct by using aqueous solutions of the acid and of sodium hydroxide. Assume thatboth solutions have the same concentration, 0.1mol/dm3.