KCSE CHEMISTRY QUESTIONS AND ANSWERS PER TOPIC
a) The table below shows properties of chlorine, bromine and iodine.
Complete the table by giving the missing information in (i),(ii) and (iii)
b) Chlorine gas is prepared by reacting concentrated hydrochloric acids with manganese (iv) oxide. i) Write the equation for reaction between concentrated hydrochloric acid and manganese (iv) oxide. ii) What is the role of manganese (Iv) oxide in this reaction c) i) Iron (II) chloride reacts with chlorine gas to form substance E. Identify substance E ii) During the reaction in c(i) above,6.30g of iron chloride were converted to 8.06 of substance E. Calculate the volume of chlorine used.(Cl = 35.5, Molar gas volume at room temperature = 24000cm3, Fe =56 ) d) Draw and name the structure of the compound formed when excess chlorine gas is reacted with ethane gas. e) Give the industrial use of chlorine
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Apiece of chromatography paper was spotted with coloured inks obtained from pens labeled 1 to 6. The diagram below shows the spots after the chromatogram was developed.
a) Which two pens contained in the same pigment?
b) Which pens contained only one pigment c) According to the chromatogram, which pigments are present in the ink of pen number 6.
ANSWERS
(a) 4 and 5 blue and Green (full) H2SO4 (aq) is on electrolyte
(b)2 and 3 yellow and red (c)Yellow and red 4 – Blue 5 – Green 2 – Yellow 3 – Red award it the colour is tied to the number
ANSWERS
Carbon dioxide can be dissolved in water under pressure to make an acidic solution.
a) What is meant by an acidic solutions? b) aqueous lead (II) nitrate reacts with the acidic solution to form a precipitate. Write anionic equation for the reaction.
The react between a piece of magnesium ribbon with excess 2m hydrochloric acid was investigated at 25°C by measuring the volume of hydrogen gas produced as the reaction progressed. The sketch below represents the graph that was obtained.
a) Name one piece of apparatus that may be used to measure the volume of hydrogen gas produced.
b) On the same diagram, sketch the curve that would be obtained if the experiment when excess chlorine gas was bubbled into hot concentrated sodium hydroxide, the following reaction occurred.
In which product did chorine undergo oxidation? Explain
State two factors which determine the stability of an isotope.
answers
answers
Write an equation for the reaction that takes place when carbon monoxide gas is passed over heated lead (II) oxide. (1mks)
Expected response
Pentane: It is non poler and will not react with sodium Hydroxide solution which is an ionic compound.
Study the set – up below and answer the question that follows.
State and explain the observations that would be made when the circuit is completed.
Name the organic compound formed when CH3CH2CH2CH2CH2OH is reacted with concentrate sulphuric acid at 170°C
answer
Four metal F,G,H and J were each separately added to cold water, and steam. The table below is a summary of the observations made and the formulae of the hydroxides formed.
a) Which two elements are likely to be in the same group of the periodic table?
b) Arrange the metals in the order of their reactivity starting with the most reactive
answers
In an experiment, a student put equal volumes of mixtures of ethanoic acid in water and ethanoic acid in hexane in two test – tubes as shown below. In each test tube, equal amounts of solid sodium hydrogen carbonate were added.
a) State the observation which was made in each test – tube
Test tube 1 Test tube 2 b) Explain the observation in (a) above
When X cm3 of a solution of 0.5m magnesium carbonate was 8.4g.
a) Write the ionic equation for the reaction that took place b) Calculate the value of X. (C = 12.0, Mg 24.0; 016.0
a) What is the name given to the smallest repeating unit of a polymer.
b) Draw the structure of the smallest repeating unit of a polyvinyl chloride
Starting with aluminium sulphate, describe how a solid sample of aluminium hydroxide could be prepared.
answers
answers
Explain why a high temperature is required for nitrogen of react with oxygen
answer
answers
When wood is burnt, a grey powder called ash remains. The ash is stirred with water and filtered, a colourless solution is obtained.
a) What is the main component of the colourless solution? b) Explain your answer in (a) above
answers
Nitrogen forms many compounds in which its oxidation state varies.
a) What is meant by oxidation state? b) What is the oxidation state of nitrogen in Mg3N2
ANSWERS
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