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The flow chart below illustrates the extraction of Zinc. Study it and answer the questions that follow:
a) Name:-
i) Gas Q
ii) Liquid R
(iii) Residues S
b) Name the sulphide ore used
c) Before the ore is roasted, it is first concentrated;
(i) Explain why it is necessary to concentrate the ore
(ii) Explain briefly the process of concentrating the ore
d) Write an equation for the reaction that takes place in the:-
(i) Roaster
(ii) Reaction chamber
(e) (i) Name one major impurity present in the sulphide ore used
(ii) Write an equation to show how the impurity in (e)(i) above is removed
f) Given that the sulphide ore contains only 45% Zinc sulphide by mass, calculate :
(i) The mass in grams of Zinc sulphide that would be obtained from 250kg of the ore.
(ii) The volume of Sulphur (IV) oxide that would be obtained from the mass of sulphide
ore at room temperature and pressure
(Zn = 65.4, S = 32.0, O= 16.0, I mole of gas occupies 24.0 liters at r.t.p)
Date posted:
November 1, 2019
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The diagram below is a flow chart for the extraction of copper. Study it and answer the questions that follow:
(a) Write the formula of the major ore of copper metal
(b) Name process II
(c) Give an equation for the reaction that occurs in stage III
(d) Explain what happens in stage IV
(e) Write half cell equations occurring at the anode and cathode in stage VII
(f) Draw a simple diagram showing the set-up that is used in electrolytic purification of copper
Date posted:
November 1, 2019
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The flow chart below shows steps used in the extraction of zinc from one of its ores.
(a) Name the process that is used in step 2 to concentrate the ore
(b) Write an equation for the reaction which takes place in step 3
Date posted:
November 1, 2019
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The stages shown in the following diagram can be used to extract zinc from its oxide.
Name the stage and the process taking place in it:-
Stage 1
Stage 2
Stage 3
Date posted:
November 1, 2019
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What properties of aluminium and its alloys make it suitable for use in making aircraft parts
Date posted:
November 1, 2019
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Suggest one manufacturing plant that can be set up near zinc extraction plant. Give
reasons for your answer
Date posted:
November 1, 2019
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Give one environmental hazard associated with the extraction of zinc metal
Date posted:
November 1, 2019
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You are provided with 20.0cm3 of 2M sodium hydroxide solution. Explain how you would prepare a solution of sodium hydroxide whose concentration is 0.16M.
Date posted:
October 31, 2019
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The following diagram represents the electrolysis of dilute sodium chloride solution using inert
electrodes
Determine the electrode at which different electrolytic products would be produced if the solution is electrolysed for several hours. Explain
Date posted:
October 31, 2019
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The standard hydrogen electrode is used as the reference electrode. Some of the difficulties in using hydrogen gas as an electrode are:
- Hydrogen is a gas at 25oC
- Hydrogen does not conduct electricity
-The half-cell reaction,
is slow and takes long to reach equilibrium.
Explain how these difficulties are solved in the standard hydrogen electrode
Date posted:
October 31, 2019
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Give the chemical formula of Zinc blende
Date posted:
October 31, 2019
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The following is an equation for the reaction between ammonia and water
Name the base in the backward reaction
Date posted:
October 31, 2019
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Calculate the volume at s.t.p of hydrogen evolved when 2A of electricity are passed
through dilute sulphuric acid for 2hours.
(Molar gas volume at s.t.p = 22.4dm3, one Faraday= 96500coulombs)
Date posted:
October 31, 2019
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State Faradays First Law of Electrolysis
Date posted:
October 31, 2019
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Copper (II) sulphate solution was electrolysed using copper electrode. A Current of 0.5A was
passed for 64.3 minutes and a mass of 0.64g of copper was deposited. (Cu = 63.5)
a) Which electrode decreased in mass during electrolysis? Explain
b) Calculate the quantity of charge needed to deposits 1 mole of copper
Date posted:
October 31, 2019
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A student set up the experiment shown below. Study it and answer the questions that follow.
a) State any two observations the student made during the experiment
b) Explain what happens to the pH of the resultant solution at the end of the experiment
Date posted:
October 31, 2019
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The following table shows the standard reduction potentials of some half cells. Study the table and refer to it to answer the questions that follow;
a) Identify the strongest oxidizing agent
b) Which substance would be used to oxidize R- ion to the atom R
c) Study the cell represented below;
i) Identify the electrodes
ii) Write equations for the reaction taking place in each half- cell
iii) Determine the cell equation and the electromotive force (e.m.f) of the cell represented in
(c) above
iv) In which direction does the electrons flow in the external circuit of the cell whose e.m.f
is determined in (iii) above
d) A steady current of 2.5A was passed for 15 minutes through a cell containing divalent ions
M2+. During this process 0.74g of metal M was deposited (IF = 96500C)
i) Calculate the quantity of electricity passed in this cell
ii) Determine the relative atomic mass of M
Date posted:
October 31, 2019
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Sodium hydroxide may be manufactured by the electrolysis of brine as in the diagram below:-
(i) State the chemical name of brine
(ii) Write the equations for the reactions at the electrodes
-Anode
-Cathode
(iii) Explain how sodium hydroxide is obtained from the product of this process
Date posted:
October 31, 2019
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The diagram below shows a Zinc –copper cell.
(i) Given the standard electrode potential of Zinc is -0.76V and that of copper is +0.34V, suggest;
(i)The identity of W
(ii) The identity of X
(iii) The equation for the overall cell reaction
(iv) The reading on the voltmeter
Date posted:
October 31, 2019
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Cheptoo set-up some apparatus as shown in the diagram below:-
At the start of the experiment, the bulb did not light:-
(a) State and explain the observation made when the tap was opened to allow the hydrogen chloride gas through the water for about 20 minutes
(b) Write the chemical equation for the reaction that took place at the cathode
Date posted:
October 31, 2019
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The flow chart below shows an analysis of mixture R that contains two salts. Study it and answer the questions that follow:-
(i) Write two ionic equations for the reactions between the cation in filtrate X and aqueous
ammonia (Ammonium hydroxide)until in excess
(ii) What conclusion can be drawn from Step IV only? Explain
(iii) What observation would indicate the presence of a NO3- ion in step I?
(iv) Write the formula of the anion in residue V. Explain
(v) Suggest the identity of the cation present in solution Z
(vi) Name the two salts present in mixture R
Date posted:
October 29, 2019
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When nitrate solution of a certain metal X was electrolysed, 1.174g of metal X was deposited by a current of 4 amperes flowing for 16 minutes. Determine the formula of the metal nitrate. (1F= 96,500, R.A.M of X= 59)
Date posted:
October 29, 2019
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The standard electrode potential for the elements chlorine and magnesium are:-
Which one of the two elements will act as an oxidizing agent? Explain.
Date posted:
October 29, 2019
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The table gives the standard redox potentials for a number of half reactions. Use it to answer the questions that follow:-
(i) Relative to which half-cell reaction are the above electrode potentials expressed?
(ii) Calculate the e.m.f of the cell made up by combining the 
electrode and 
electrode
(iii) Which of the substances listed in the above table is :-
I. The strongest oxidising agent
II. The strongest reducing agent
(iv) Which substances could be used to convert iodide ions to iodine? Write balanced equations for any possible conversions
Date posted:
October 29, 2019
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Study the standard electrode potential for the half-cells given below and answer the questions that follow.(The letter do not represent the actual symbols of the elements)
i) Identify the strongest oxidizing agents. Give a reason for your answer
ii) Which two half-cells would produce the highest potential difference when combined?
iii) In the space below draw a complete electro-chemical cell of the two-half cells mentioned
in (ii) above
Date posted:
October 29, 2019
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Study the flow chart below and answer the questions that follow:
(a) Name gas Q
(b) With the help of diagram, describe how step (V) is carried out
Date posted:
October 29, 2019
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What mass of Zinc will be deposited from a solution of Zinc (II) Chloride when a current of 3A is passed through the Zinc (II) Chloride solution during electrolysis for 50 minutes?
(Zn= 65, 1 Faraday = 96500C)
Date posted:
October 29, 2019
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In an electrolysis, a current of 200A was passed through molten oxide of metal Q for 58 minutes and 64.8g of the metal deposited. Determine;
i) Charge on metal Q
ii) The volume of oxygen gas produced at standard temperature and pressure
Q = 27 IF = 96500C, molar gas volume stp =22.4dm3
Date posted:
October 29, 2019
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The following is a thermochemical equation for the reaction between hydrogen and oxygen
Calculate the bond energy between the elements in water given that:
Date posted:
October 29, 2019
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The graph below represents the volume of gas collected against time when dilute sulphuric acid is reacted with Zinc granules:-
(a) Determine the rate of reaction between the 1st and 3rd minute
(b) When did the reaction stop?
(c) Give a possible reason for the reaction to stop
Date posted:
October 29, 2019