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Chemistry -
1997( I.C.S.E)
You are on questions 3 to 7 of Set
II
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SECTION - I (40 marks)
Answer
all questions. |
Q 3
(a)Write equations for the following reactions:
(i) burning of ammonia in oxygen;
(ii) catalytic oxidation of
ammonia.
Q 3 (b)(i) What would you see
in(a)(i) above?
(ii) Name the
catalyst used in(a)(ii).
(iii) In
the reaction referred to in (a)(ii) the catalyst glows red hot.
Why?
(iv) What is the name of the
industrial process which starts with the reaction referred to in (a)(ii)?
Q 3(c) (i) How soluble is ammonia
in water?
(ii) Give two reasons to
show that the solution of ammonia in water contains hydroxide
ions.
(iii) Name a simple method
you would employ to prepare ammonium salt in your laboratory.
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Q 4(a)Calculate the
empirical formula of the compound having 37.6 % sodium, 23.1%
silicon and 39.3% oxygen. (work to two decimal places).
[O=16;Na=23;Si=28]
Q 4(b)The empirical formula of a
compound is C2H5. It has a vapour density of
29. Determine the relative molecular mass of the compound and hence
its molecular formula.
Q 4(c) Solid ammonium
dichromate (relative molecular mass = 252) decomposes according to
the following equation:
(NH4)2Cr2O7® N2 + Cr2O3 +
4H2O
(i) What
volume of nitrogen, at STP will be evolved when 63g of ammonium
dichromate is decomposed?
(ii) If
63g of ammonium dichromate is heated above 1000c , what
will be the loss of mass? (H=1;N=14;O=16;Cr=52).
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Q5(a) The
following substances are put into the blast furnace when
manufacturing iron : iron ore,
coke, limestone and hot air.
(i)
what is the name of the most common ore of iron and what is its
chemical formula ?
(ii) what is
the purpose of using (1) the coke (2) the limestone?
(iii) write the equation for the
reduction reaction which produces iron.
(iv) Name the two substances which separate at the bottom of
the blast furnace.
Q 5(b)(i) What is the
main impurity present in the iron produced in the blast
furnace?
(ii) By what chemical
process is this impurity removed in steelmaking?
(iii) What is added
to steel to make stainless steel?
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Q6(a)(i) Write
the equation for the laboratory preparation of the sulphur dioxide
from sodium sulphite.
(ii)
How is the sulphur dioxide collected?
(iii) What does the method of collection tell you about
the density of sulphur dioxide?
(iv) What do you see when sulphur dioxide is bubbled
through an acidified potassium dichromate solution?
Q 6(b)Write one equation
in each case to show the action of sulphur dioxide?
(i) a reducing agent;
(ii) an oxidizing agent;
(iii) an acid anhydride.
Q 6(c)(i) what is the
similarity in the use of sulphur dioxide and chlorine as
bleaching agents?
(ii) When
chlorine is involved in bleaching , what is the type of
chemical reaction that changes the coloured compound to a colourless
one?
(iii) What is the
reason for not using chlorine to bleach wool?
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Q7.(a)Outline the
steps required to convert hydrogen chloride to anhydrous Iron (III)
Chloride. Write the equations for the reactions which take
place.
7(b)(i) What are the two steps necessary to
change Lead Carbonate into Lead Chloride?
(ii) Give the name of soluble lead salt and write
the equation for the action of heat on this salt.
(iii)Write the equation for the preparation of
nitric acid from potassium nitrate.
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