When a burning magnesium is introduced into a gas jar containing carbon dioxide, the intense heat burning magnesium produces, decomposes the carbon dioxide gas into carbon and oxygen. This oxygen now supports the continuous burning of magnesium.
Kavungya answered the question on March 25, 2019 at 09:46
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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)
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The boiling points of some compounds of hydrogen with some elements in group 4 and 6 of the periodic table are given below.
(Solved)
The boiling points of some compounds of hydrogen with some elements in group 4 and 6 of the periodic table are given below.
a) Which of the compounds CH4 and SiH4 has the stronger inter molecular forces?Explain.
(b) Explain why the boiling points of H2O and H2S show different trends from that of CH4 and SiH4.
Date posted:
March 19, 2019
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Answers (1)
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In terms of structure and bonding explain why silicon (IV) oxide is a solid while sulphur (IV) oxide is a gas at room temperature.
(Solved)
In terms of structure and bonding explain why silicon (IV) oxide is a solid while sulphur (IV) oxide is a gas at room temperature.
Date posted:
March 19, 2019
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Answers (1)
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The data given below was recorded when metal M was completely burnt in air. M is not the actual symbol of the metal. (RAM M...
(Solved)
The data given below was recorded when metal M was completely burnt in air. M is not the actual symbol of the metal. (RAM M = 56.0, O=16)
Mass of empty crucible and lid = 5.240g
Mass of crucible, lid and metal m = 5.352g
Mass of crucible, lid, metal oxide = 5.400g
(a) Determine the mass of
(i) Metal m
(ii) Oxygen.
(b) Determine the empirical formula of the meat oxide.
Date posted:
March 19, 2019
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Answers (1)
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In an experiment air was passed through several reagents as shown in the flow chart below.
(Solved)
In an experiment air was passed through several reagents as shown in the flow chart below.
(a) Write an equation for the reaction which takes place in the chamber with magnesium powder.
(b) State the Role of concentrated potassium hydroxide solution.
(c) What observation is made in the chamber containing copper turnings.
Date posted:
March 19, 2019
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Answers (1)
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List the uses of chlorine gas and its compounds.
(Solved)
List the uses of chlorine gas and its compounds.
Date posted:
March 5, 2019
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Answers (1)
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Explain the effects of chlorine gas on a burning candle.
(Solved)
Explain the effects of chlorine gas on a burning candle.
Date posted:
March 5, 2019
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Answers (1)