Page 165 - ICSE Chemistry 8

AT LENGTH

A. Read the following ac vity performed to demonstrate the forma on of hydrogen chloride gas.
Iden fy the incorrect parts.
To show the forma on of hydrogen chloride gas

• Take two jars. Fill both the jars with hydrogen gas.
• Invert the jar fi lled with hydrogen over the jar fi lled with chlorine gas.

• Remove the lids of both jars to mix the two gases.
• Expose the two jars to sunlight.

Observa on:
The bluish yellow colour of hydrogen gas disappears and a red-coloured gas is formed.

• Now bring a glass rod dipped sodium chloride solu on near the mouth of the gas jar.
Observa on:

Dense green fumes of sodium chloride are produced.
This shows the forma on of sodium chloride gas when hydrogen gas reacts with chlorine in the presence
of diff used sunlight

B. Answer in detail.

1. Discuss the occurrence of hydrogen in nature.
2. With the help of examples, discuss the prepara on of hydrogen by the ac on of water on metals.

3. Give balanced equa ons to show that hydrogen can be prepared by the ac on of dilute acids on
metals.

4. How is hydrogen prepared by electrolysis of water?
5. Describe the laboratory prepara on of hydrogen with the help of a diagram.

6. List safety precau ons to be taken during laboratory prepara on of hydrogen.
7. Write a note on oxida on and reduc on reac ons. Also, explain redox reac ons with the help of
examples.
8. List a few uses of hydrogen.

OBSERVE AND PERFORM

Observe the given ac vity series on page 138 carefully and answer the following ques ons.
1. Name the most reac ve metal and the least reac ve metal.
2. Name the metals that react with cold water, steam and acids to produce hydrogen gas and
hydroxides.
3. Name the metals that cannot react with cold water and react only with steam and acids to produce
hydrogen gas and metal oxides.

4. Name the metals that react only with dilute acids to produce hydrogen gas.
5. Name the metals that do not react with water, steam or dilute acids.

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