a) State how burning can be used to distinguish between ethane and ethyne.
Explain your answer.
b) Draw the structural formula of the third member of the homologous series of ethyne.
c) The flow chart below shows a series of reactions starting with ethanol.
Study it and answer the questions that follow.
ii) Write the equation for the combustion of ethanol
iii) Explain why it is necessary to use high pressure to change gas B into the polymer
iv) State one use of methane
The set – up below was used to prepare hydrogen gas
a) Complete the diagram to show how a dry sample of hydrogen gas can be collected
b) Write an equation for the reaction, which takes place when hydrogen gas burns in air.
c) i)1.2 litres of hydrogen gas produced at room temperature and pressure when 3.27g of zinc was used. Determine the relative atomic mass of zinc.(Molar gas volume is 24 litres)
d) State two industrial uses of hydrogen gas.
The basic raw material for extraction of aluminium is bauxite
a) Name the method that is used to extract aluminium from bauxite
b) Write the chemical formula of the major component of bauxite
c) i) Name two major impurities in bauxite
ii) Explain how the impurities in bauxite are removed
d) Cryolite is used in the extraction of aluminium from bauxite.
State its function
f) Aluminium is a reactive metal yet utensils made of aluminium do not corrode easily. Explain this observation
Excess marble chips (calcium carbonate ) was put in a beaker containing 100cm3 of dilute hydrochloric acid. The beaker was then placed on a balance and the total loss in mass recorded after every two minutes as shown in the table below.
a) Why was there a loss in mass?
b) Calculate the average rate of loss in mass between:
i) 0 and 2 minutes
ii) 6 and 8 minutes
iii) Explain the difference in the average rates of reaction in (b) (i) and (ii) above
c) Write the equation for the reaction which takes place in the beaker
d) State three ways in which the rate of the reaction above could be increased
e) The solution in the beaker was evaporated to dryness what would happen if the open beaker and its contents were left in the laboratory overnight.
f) Finally some water was added to the contents of the beaker.
When aqueous sodium sulphate was added to the contents of the beaker, a white precipitate was formed.
i) Identify the white precipitate
ii) State one use of the substance identified in (f) (i) above
i) Identify the particles emitted in steps I and III
ii) Write the nuclear equation for the reaction which takes place in step V
The table below give the percentages of a radioactive isotope of Bismuth that remains after decaying at different times.
i) On the grid provided, plot a graph of the percentage of Bismuth remaining (Vertical axis) against time.
ii) Using the graph, determine the:
I. Half – life of the Bismuth isotope
II. Original mass of the Bismuth isotope given that the mass that remained after 70 minutes was 0.16g
d) Give one use of radioactive isotopes in medicine
a) The diagram below is a cross- section of a dry cell. Study it and answer the questions that follow.
i) On the diagram, show with a (+) sign the positive terminal
ii) Write the equation for the reaction in which electrons are produced
iii) The zinc can is lined with ammonium chloride and zinc chloride paste.
iv) Give one advantage and one disadvantage of dry cells.
b) The set – up below was used to (electrolyse roller lead (II) ionide.
i) State the observation that was made at the anode during the electrolysis.
Give a reason for your answer.
ii) A current of 0.5 A was passed for two hours. Calculate the mass of lead that was deposited (Pb = 1F = 9,500C)
a) The chart below is an outline of part of the periodic table.
With the help of vertical and horizontal lines, indicate the direction of increasing metallic nature of the elements.
Which types of elements are represented in the shaded area?
b) i) Element A is the same group of the periodic table as chlorine.
Write the formula of the compound formed when A reacts with potassium metal.
ii) What type of bonding exists in the compound formed in (b) (l) above?
Give a reason for your answers.
c) Starting with aqueous magnesium sulphate, describe how you would obtain a sample of magnesium oxide.
d) Write two ionic equations to show that aluminum hydroxide is amphoteric
During purification of copper by electrolysis, 1.48g of copper were deposited when current was passed through aqueous copper(II) sulphate for 2 1/2 hours. Calculate (CU = 63.5, 1 Faraday = 96,500C).
The graph below shows the behaviour of a fixed mass of a gas at constant temperature.
a) What is the relationship between the volume and the pressure of the gas?
b) 3 litres of oxygen gas at one atmosphere pressure were compressed to two atmospheres at constant temperature. Calculate the volume occupied by the oxygen gas
Explain why the reactivity of group (VII) elements decreases down the group
a) State the observation made when excess pentane is reacted with bromine gas
b) Name the compound formed in (a) above.
The set – up below was used to prepare hydrogen chloride a gas and react it with iron powder. Study it and answer the questions that follow.
At the end of the reaction, the iron powder turned into a light green solid.
a) Identity the light green solid.
b) At the beginning of the experiment, the Ph of the solution in container L was about 14.. At the end, the pH was found to be 2. Explain
An organic compound with the formula C4 H10 O reacts with potassium metal to give hydrogen gas and white solid
(a) Write the structural formula of the compound
(b) To which homologous series does the compound belong?
(c) Write the equation for the reaction between the compound and potassium metal
Brass is an alloy of zinc and copper. Give one use of brass
Maurice Atika is a teacher and a netprenuer.