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Why is it better to use indicators rather than the sense of taste when testing for acids and alkalis?
(Solved)
Why is it better to use indicators rather than the sense of taste when testing for acids and alkalis?
Date posted:
March 25, 2019
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Answers (1)
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Explain briefly the following observations about a sample of hard water (a) when boiled it formed some white precipitate (b) even after boiling the water...
(Solved)
Explain briefly the following observations about a sample of hard water (a) when boiled it formed some white precipitate (b) even after boiling the water formed scum with soap (c) Sodium Carbonate made the water completely soft.
Date posted:
March 25, 2019
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Answers (1)
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Name the materials used to prepare soaps and soapless detergents.
(Solved)
Name the materials used to prepare soaps and soapless detergents.
Date posted:
March 25, 2019
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Answers (1)
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In an experiment, dry hydrogen chloride gas was passed through heated Zinc turnings as shown in the diagram below. The gas produced was then passed...
(Solved)
In an experiment, dry hydrogen chloride gas was passed through heated Zinc turnings as shown in the diagram below. The gas produced was then passed through heated Lead II Oxide.
(i) What is the function of the water in the flask?
(ii) Write equations for the reactions that took place in the tubes.
(iii) How would the total mass of tube V and its contents compare before and after the experiment? Explain.
Date posted:
March 25, 2019
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Answers (1)
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Paper chromatography of a plant extract gave the following results.
Which Solvent is the most suitable for purifying the extract? Explain.
(Solved)
Paper chromatography of a plant extract gave the following results.
Which Solvent is the most suitable for purifying the extract? Explain.
Date posted:
March 25, 2019
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Answers (1)
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Carbon dioxide doesn’t support combustion, yet burning of magnesium ribbon introduced in jar of carbon dioxide continues to burn. Explain this.
(Solved)
Carbon dioxide doesn’t support combustion, yet burning of magnesium ribbon introduced in jar of carbon dioxide continues to burn. Explain this.
Date posted:
March 25, 2019
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Answers (1)
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Describe an experiment to investigate the “active part of air”.
(Solved)
Describe an experiment to investigate the “active part of air”.
Date posted:
March 25, 2019
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Answers (1)
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Briefly explain how ice-cream vendors use solid carbon dioxide (dry ice) to keep the ice-cream frozen.
(Solved)
Briefly explain how ice-cream vendors use solid carbon dioxide (dry ice) to keep the ice-cream frozen.
Date posted:
March 25, 2019
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Answers (1)
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The following are some of the methods used to collect gases. With reasons state which method is suitable for each of the following gases, Ammonia,...
(Solved)
The following are some of the methods used to collect gases. With reasons state which method is suitable for each of the following gases, Ammonia, carbon dioxide, oxygen.
Date posted:
March 25, 2019
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Answers (1)
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Where in Kenya is Crystallization method used? State what happens briefly.
(Solved)
Where in Kenya is Crystallization method used? State what happens briefly.
Date posted:
March 25, 2019
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Answers (1)
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When fine chalk is suspended in water and viewed through a microscope the chalk particles appear to move in a random fashion. This motion is...
(Solved)
When fine chalk is suspended in water and viewed through a microscope the chalk particles appear to move in a random fashion. This motion is a result of?
Date posted:
March 25, 2019
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Answers (1)
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Against each mixture write down suitable methods of separation.
(a) Coloured extracts of grass dissolved in ethanol.
(b) Kerosine from Crude oil.
(c) Paraffin from water.
(d)...
(Solved)
Against each mixture write down suitable methods of separation.
(a) Coloured extracts of grass dissolved in ethanol.
(b) Kerosine from Crude oil.
(c) Paraffin from water.
(d) Iron filings from Sulphur powder.
(e) Ammonium chloride from Sodium chloride.
(f) Seawater, to obtain salt.
(g) Blue Copper Sulphate crystals from aqueous copper sulphate.
Date posted:
March 25, 2019
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Answers (1)
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Why is fractional distillation suitable for separating crude oil constituents?
(Solved)
Why is fractional distillation suitable for separating crude oil constituents?
Date posted:
March 25, 2019
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Answers (1)
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Which observation made when helium is ignited in oxygen?
(Solved)
Which observation made when helium is ignited in oxygen?
Date posted:
March 24, 2019
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Answers (1)
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The flow chart below shows the various stages of water treatment. Study it and answer the questions that follow.
(Solved)
The flow chart below shows the various stages of water treatment. Study it and answer the questions that follow.
i) What is the purpose of filtration unit I
ii) What is the name of process X
What is the purpose of
I.Process X
II.Addition of sodium hypochlorite
b) A sample of tap water was found to contain magnesium sulphate.
i) What type of hardness was present in the water?
ii) Explain how the hardness can be removed.
c)i) Describe how a solid sample of calcium carbonate can be prepared starting with magnesium oxide.
ii) State one use of calcium carbonate.
Date posted:
March 19, 2019
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Answers (1)
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a)The set up below was used during electrolysis of aqueous copper (II) sulphate using inert electrodes.
(Solved)
a)The set up below was used during electrolysis of aqueous copper (II) sulphate using inert electrodes.
i) Name a suitable pair of electrodes for this experiment.
ii) Identify the ions and cations in the solution.
iii) On the diagram label the cathode.
iv) Write ionic equations for the reactions that took place at the anode
v) Explain the change that occurred to the Copper (II) Sulphate solution during the experiment.
vi) During the electrolysis a current of 2 amperes was passed through the solution for 4 hours. Calculate the volume of the gas produced at the anode. (1 Faraday = 96500 coulombs and volume of gas at room temperature is 24000cm3 )
b) i) Draw a diagram to show how an impure copper lump can be refined through electrolysis.
ii) State one other use of electrolysis other than the one shown in b (ii) above.
Date posted:
March 19, 2019
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Answers (1)
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(a) Below is a paper chromatogram of pure substances W, X and Y
(Solved)
(a) Below is a paper chromatogram of pure substances W, X and Y
The mixture K contains substances W and X only. Indicate on the diagram the chromatogram of K.
(b) State one application of chromatography.
Date posted:
March 19, 2019
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Answers (1)
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Moist hydrogen sulphide gas was passed through a tube containing wet sulphur (IV) oxide gas as shown below.
(Solved)
Moist hydrogen sulphide gas was passed through a tube containing wet sulphur (IV) oxide gas as shown below.
(a) State the observation (s) made.
(b) Write an equation for the reaction above.
(c) Giving a reason, which substance undergoes reduction above.
Date posted:
March 19, 2019
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Answers (1)
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Give two differences between chemical reactions and nuclear reactions.
(Solved)
Give two differences between chemical reactions and nuclear reactions.
Date posted:
March 19, 2019
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Answers (1)
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0.585g of sodium chloride were dissolved in 50cm³ of de-ionised water. The temperature of the water dropped from 29°C to 17°C. Find the molar heat...
(Solved)
0.585g of sodium chloride were dissolved in 50cm³ of de-ionised water. The temperature of the water dropped from 29°C to 17°C. Find the molar heat of solution of sodium chloride. Specific heat capacity of solution 4.2 kJk-2Kg-1, density of solution is 1g/cm³. (Na - 23.0, Cl = 35.5)
Date posted:
March 19, 2019
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Answers (1)