Boiling point increases with increase in molecular mass
johnmulu answered the question on February 21, 2017 at 11:26
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Pentane and ethanol are miscible. Describe how water could be used to separate a mixture of pentane and ethanol
(Solved)
Pentane and ethanol are miscible. Describe how water could be used to separate a mixture of pentane and ethanol
Date posted:
February 21, 2017
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Answers (1)
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State the observation that would be made when a piece of sodium metal is placed in samples of:
(Solved)
State the observation that would be made when a piece of sodium metal is placed in samples of:
i) Pentane
ii) Pentanol
Date posted:
February 21, 2017
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Answers (1)
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a) Name the raw material from which sodium is extracted.
b) Give a reason why sodium is extracted using electrolysis
c) Give two reasons of sodium metal
(Solved)
a) Name the raw material from which sodium is extracted.
b) Give a reason why sodium is extracted using electrolysis
c) Give two reasons of sodium metal
Date posted:
February 21, 2017
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Answers (1)
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Aluminium is both malleable and ductile....
(Solved)
Aluminium is both malleable and ductile
a) What is meant by?
i) Malleable
ii) Ductible
b) State one use of alumunium based on:
i) Malleability
ii) Ductility
Date posted:
February 21, 2017
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Answers (1)
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a) Explain why the metals magnesium and aluminium are good conductors of electricity
b) Other than cost, give two reasons why aluminium is used for making electric cables while magnesium is not.
(Solved)
a) Explain why the metals magnesium and aluminium are good conductors of electricity
b) Other than cost, give two reasons why aluminium is used for making electric cables while magnesium is not.
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 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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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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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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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)
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An element P has a relative atomic mass of 88. When a current of 0.5 amperes was passed through the fused chloride of P for 32 minutes and 10 seconds, 0.44 g of P were deposited at the cathode.
(Solved)
An element P has a relative atomic mass of 88. When a current of 0.5 amperes was passed through the fused chloride of P for 32 minutes and 10 seconds, 0.44 g of P were deposited at the cathode. Determine the charge on an ion of P.
(1 Faraday = 96500 Coulombs)
Date posted:
February 16, 2017
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Answers (1)
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Give reason why aluminium metal would protect iron from rusting better than zinc metal
(Solved)
Give reason why aluminium metal would protect iron from rusting better than zinc metal.
Date posted:
February 16, 2017
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Answers (1)
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Aqueous potassium sulphate was electrolyzed using platinum electrodes in a cell......
(Solved)
Aqueous potassium sulphate was electrolyzed using platinum electrodes in a cell.
a) Name the products formed at the cathode and anode
b) How does the concentration of the electrolyte change during electrolysis?
c) Why would it not be advisable to electrolyse aqueous potassium sulphate using potassium metal electrodes?
Date posted:
February 16, 2017
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Answers (1)
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State and explain how the rate of reaction between zinc granules and steam can be increased
(Solved)
State and explain how the rate of reaction between zinc granules and steam can be increased.
Date posted:
February 15, 2017
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Answers (1)
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State the Hess's Law and its applications
(Solved)
State the Hess's Law and its applications.
Hess's law States that if a chemical change can be made to take place in two or more steps, the amount of the total heat change is the same no matter which method is used.
Its applications are:
1.Determination of heat of formation of substances which cannot be measured experimentally. Substances like methane,carbon dioxide and benzene cannot be prepared by uniting there elements. Therefore it is not possible to measure the heat of formation of certain compound directly.
2.Determination of heat of transition. The heat of transition from one allotropic form to another can also be calculated with the help of Hess's law.
3.Determination of heat of various reaction. By using Hess's law we can calculate enthalpies of many reactions which can not be measured directly. For example the enthalpy of dimerization of nitrogen dioxide.
Date posted:
February 15, 2017
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Answers (1)
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State two factors that should be considered when choosing fuel for cooking
(Solved)
State two factors that should be considered when choosing fuel for cooking.
Date posted:
February 15, 2017
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Answers (1)