a) Electrolysis
b) Al2O3.2H2O
c) i) Iron (iii) oxide
ii) silica
ii) Add hot concentrated sodium hydroxide (NaOH). Silica and alumium oxide (Al2O3) dissolves. Filter iron (iii) oxide. Bubble Carbon (IV) oxide (CO2) through the filtrate to precipitate aluminium hydroxide. Filter to obtain aluminium hydroxide as a residue
d) It lowers the melting point of Aluminum oxide
e) The reaction of aluminium with oxygen forms a firm layer of aluminium oxide
The layer prevents aluminium metal from further attack.
johnmulu answered the question on February 21, 2017 at 07:14
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Brass is an alloy of zinc and copper. Give one use of brass.
(Solved)
Brass is an alloy of zinc and copper. Give one use of brass.
Date posted:
February 21, 2017
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Answers (1)
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Iron is extracted from its ore by the blast furnace process, name one ore from which iron is extracted.
(Solved)
Iron is extracted from its ore by the blast furnace process
a) Name one ore from which iron is extracted.
b) One of the impurities in iron is removed in the form of calcium silicate. Write an equation for the reaction in which calcium silicate is produced.
Date posted:
February 21, 2017
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Answers (1)
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When the oxide of element H was heated with element H was heated with powdered carbon the mixture glowed and carbon (IV) oxide was formed. When the experiment was repeated using the oxide of element J, there was no apparent reaction.
(Solved)
When the oxide of element H was heated with element H was heated with powdered carbon the mixture glowed and carbon (IV) oxide was formed. When the experiment was repeated using the oxide of element J, there was no apparent reaction.
a) Suggest one method that can be used to extract element J from its oxide
b) Arrange the elements H, J and carbon in the order of their decreasing reactivity.
Date posted:
February 21, 2017
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Answers (1)
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Aluminium metal is a good conductor and is used for overhead cables. State any other two properties that make aluminium suitable for this use.
(Solved)
Aluminium metal is a good conductor and is used for overhead cables. State any other two properties that make aluminium suitable for this use.
Date posted:
February 21, 2017
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Answers (1)
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State one advantage and one disadvantage of using petrol containing tetraethyl lead in motor vehicles
(Solved)
Give one advantage and one disadvantage of using petrol containing tetraethyl lead in motor vehicles
Date posted:
February 21, 2017
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Answers (1)
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Explain why the sodium metal is stored under kerosene.
(Solved)
Explain why the sodium metal is stored under kerosene.
Date posted:
February 21, 2017
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Answers (1)
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Explain why it is not advisable to use wood ash for cleaning aluminium utensils
and state the advantage of using duralumin in place of aluminium for manufacture of aeroplane n parts
(Solved)
a) Explain why it is not advisable to use wood ash for cleaning aluminium utensils
b) Duralumin is an alloy of aluminium. What is the advantage of using duralumin in place of aluminium for manufacture of aeroplane parts
Date posted:
February 21, 2017
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Answers (1)
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State three uses of copper
(Solved)
State two uses of copper
Date posted:
February 21, 2017
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Answers (1)
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State two applications of electrolysis
(Solved)
State two applications of electrolysis.
Date posted:
February 20, 2017
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Answers (1)
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Calculate the time in minutes required to deposit 1.184 g of copper if a current of 2 amperes was used. (1 Faraday = 96500 coulombs, Cu = 63.5).
(Solved)
Calculate the time in minutes required to deposit 1.184 g of copper if a current of 2 amperes was used. (1 Faraday = 96500 coulombs, Cu = 63.5).
Date posted:
February 18, 2017
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Answers (1)
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A student electroplated a spoon with copper metal. Write an equation for the process that took place at the cathode.
(Solved)
A student electroplated a spoon with copper metal. Write an equation for the process that took place at the cathode.
Date posted:
February 18, 2017
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Answers (1)
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Hydrogen and oxygen can be obtained by electrolysis of acidified water. Using equations for the reactions at the electrodes, explain why the volume of hydrogen obtained is twice that of oxygen.
(Solved)
Hydrogen and oxygen can be obtained by electrolysis of acidified water. Using equations for the reactions at the electrodes, explain why the volume of hydrogen obtained is twice that of oxygen.
Date posted:
February 18, 2017
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Answers (1)
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State and explain the observations made when a copper rod is placed in a beaker containing silver nitrate solution
(Solved)
State and explain the observations made when a copper rod is placed in a beaker containing silver nitrate solution.
Date posted:
February 16, 2017
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Answers (1)
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During the electrolysis of aqueous silver nitrate, a current of 5.0 A was passed through the electrolyte for 3 hours.
(Solved)
During the electrolysis of aqueous silver nitrate, a current of 5.0 A was passed through the electrolyte for 3 hours.
a) Write the equation for the reaction which took place at the anode
b) Calculate the mass of silver deposited. (Ag = 108; IF = 96500 C)
Date posted:
February 16, 2017
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Answers (1)
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When brine is electrolysed using inert electrodes, chlorine gas is liberated at the anode instead of oxygen. Explain this observation and name the product formed at the cathode.
(Solved)
a) When brine is electrolysed using inert electrodes, chlorine gas is liberated at the anode instead of oxygen. Explain this observation.
b) Name the product formed at the cathode.
Date posted:
February 16, 2017
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Answers (1)
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State how the following substances conduct electricity
(Solved)
State how the following substances conduct electricity:
i) Molten calcium chloride
ii) Graphite
Date posted:
February 16, 2017
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Answers (1)
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What is an electrolyte?
(Solved)
What is an electrolyte?
Date posted:
February 16, 2017
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Answers (1)
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When a current of 0.82 A was passed for 5 hours through an aqueous solution of metal Z, 2.65 g of the metal were deposited....
(Solved)
When a current of 0.82 A was passed for 5 hours through an aqueous solution of metal Z, 2.65 g of the metal were deposited. (1 Faraday = 96500 Coulombs: Relative atomic mass of Z = 52)
(a) Calculate the number of faradays used.
(b) Determine the charge on the ion of metal P.
(c) Write the equation for the formation of ion of P.
Date posted:
February 16, 2017
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Answers (1)
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Brine usually contains soluble calcium and magnesium salts. Explain how sodium carbonate is used to purify brine
(Solved)
Brine usually contains soluble calcium and magnesium salts. Explain how sodium carbonate is used to purify brine
Date posted:
February 16, 2017
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Answers (1)
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During purification of copper by electrolysis, 1.48 g of copper were deposited when current was passed through aqueous copper (II) sulphate for 2$\frac{1}{2}$ hours. Calculate the amount of current used. (Cu = 63.5; 1 F = 96500 C
(Solved)
During purification of copper by electrolysis, 1.48 g of copper were deposited when current was passed through aqueous copper (II) sulphate for 2$\frac{1}{2}$ hours. Calculate the amount of current used. (Cu = 63.5; 1 F = 96500 C).
Date posted:
February 16, 2017
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Answers (1)