a) Colourless solution becomes brown or black: Formula = I2(aq)
b) A blue precipitate dissolves to form a deep blue solution:
Formula = Cu(NH3)42+
johnmulu answered the question on February 13, 2017 at 13:57
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Hardness of water may be removed by either boiling or addition of chemicals
(Solved)
Hardness of water may be removed by either boiling or addition of chemicals.
a) Write an equation to show how boiling removes hardness of water.
b) Name two chemicals that are used to remove hardness of water.
Date posted:
February 13, 2017
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Answers (1)
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The elements nitrogen, phosphorous and potassium are essential for plant growth
(Solved)
The elements nitrogen, phosphorous and potassium are essential for plant growth.
Potassium in fertilizers may be in the form of potassium nitrate.
Describe how a sample of a fertilizer may be tested to find out if it contained nitrate ions.
Date posted:
February 13, 2017
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Answers (1)
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Name two methods that can be used to remove permanent hardness from water
(Solved)
Name two methods that can be used to remove permanent hardness from water.
Date posted:
February 13, 2017
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Answers (1)
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Explain why permanent hardness in water cannot be removed by boiling
(Solved)
Explain why permanent hardness in water cannot be removed by boiling.
Date posted:
February 13, 2017
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Answers (1)
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Starting from solid magnesium oxide, describe how a solid sample of magnesium hydroxide can be prepared
(Solved)
a) Starting from solid magnesium oxide, describe how a solid sample of magnesium hydroxide can be prepared.
b) Give one use of magnesium hydroxide.
Date posted:
February 13, 2017
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Answers (1)
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Water from a town in Kenya is suspected to contain chloride ions but not sulphate ions. Describe how the presence of the chloride ions in water can be shown
(Solved)
Water from a town in Kenya is suspected to contain chloride ions but not sulphate ions. Describe how the presence of the chloride ions in water can be shown.
Date posted:
February 13, 2017
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Answers (1)
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Zinc oxide reacts with acids and alkalis (a) Write the equation for the reaction between zinc oxide and...
(Solved)
Zinc oxide reacts with acids and alkalis
a) Write the equation for the reaction between zinc oxide and
i)Dilute sulphuric (VI) acid
ii) Sodium hydroxide solution
Date posted:
February 13, 2017
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Answers (1)
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Starting with aluminium sulphate, describe how solid sample of aluminium hydroxide could be prepared
(Solved)
Starting with aluminium sulphate, describe how solid sample of aluminium hydroxide could be prepared.
Date posted:
February 13, 2017
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Answers (1)
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State the constant force that opposes the motion of a stone initially at rest, as it fails through air from a tall building
(Solved)
State the constant force that opposes the motion of a stone initially at rest, as it fails through air from a tall building.
Date posted:
February 11, 2017
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Answers (1)
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Neutralization is one of the methods of preparing salts (i) What is meant by neutralization
(Solved)
Neutralization is one of the methods of preparing salts
i) What is meant by neutralization
ii) Describe how would prepare crystals of sodium nitrate starting with 200 cm3 of 2M sodium hydroxide
iii) Write an equation for the reaction that takes place when a solid sample of sodium nitrate is heated.
Date posted:
February 10, 2017
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Answers (1)
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(a) State one cause of temporary hardness in water (b) How does distillation remove hardness from water?
(Solved)
a) State one cause of temporary hardness in water
b) How does distillation remove hardness from water?
Date posted:
February 10, 2017
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Answers (1)
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A student was supplied with a colourless liquid suspected to be water (i) Describe one chemical test that could have been used to show that the liquid was water
(Solved)
A student was supplied with a colourless liquid suspected to be water
i) Describe one chemical test that could have been used to show that the liquid was water
ii) How could it have been shown that the liquid was pure water
Date posted:
February 10, 2017
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Answers (1)
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When solid magnesium carbonate was added to a solution of hydrogen chloride in methylbenzene, there was no apparent reaction
(Solved)
When solid magnesium carbonate was added to a solution of hydrogen chloride in methylbenzene, there was no apparent reaction. On addition of water to the resulting mixture, there was vigorous effervescence. Explain these observations.
Date posted:
February 10, 2017
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Answers (1)
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State and explain one disadvantage of using hard water in boilers
(Solved)
State and explain one disadvantage of using hard water in boilers.
Date posted:
February 10, 2017
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Answers (1)
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Give one advantage of using hard water for domestic purposes
(Solved)
Give one advantage of using hard water for domestic purposes
Date posted:
February 10, 2017
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Answers (1)
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A bee-keeper found that when stung by a bee, application of a little solution of sodium hydrogen carbonate helped to relieve the irritation from the affected area. Explain
(Solved)
A bee-keeper found that when stung by a bee, application of a little solution of sodium hydrogen carbonate helped to relieve the irritation from the affected area. Explain
Date posted:
February 10, 2017
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Answers (1)
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Distinguish between a strong and a weak acid. Give an example of each
(Solved)
Distinguish between a strong and a weak acid. Give an example of each.
Date posted:
February 10, 2017
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Answers (1)
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A sample of water drawn from a river passing through an agricultural district was divided into two portions
(Solved)
A sample of water drawn from a river passing through an agricultural district was divided into two portions. The first portion gave a white precipitate when acidified barium chloride was added. The second portion when warmed with aqueous sodium hydroxide gave a colourless gas which turned a moist red litmus paper blue.
i) Identify the ions present in the river water
ii) Suggest the possible source (s) of ions identified in (a) above
Date posted:
February 10, 2017
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Answers (1)
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Give the formula of an oxide which reacts with both dilute hydrochloric acid and hot concentrated sodium hydroxide
(Solved)
a) Give the formula of an oxide which reacts with both dilute hydrochloric acid and hot concentrated sodium hydroxide
b) Give the formulae of the products formed when the oxide in (a) above reacts with excess hot concentrated sodium hydroxide.
Date posted:
February 10, 2017
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Answers (1)
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90 cm3 of 0.01M calcium hydroxide were added to a sample of water containing 0.001 moles of calcium hydrogen carbonate
(Solved)
90 cm3 of 0.01M calcium hydroxide were added to a sample of water containing 0.001 moles of calcium hydrogen carbonate
a) Write an equation for the reaction which took place
b) Calculate the number of moles of calcium ions in 90 cm3 of 0.01M calcium hydroxide.
c) What would be observed if soap solution was added dropwise to a sample of the water after the addition of calcium hydroxide? Give a reason.
Date posted:
February 10, 2017
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Answers (1)