Chemistry
In the laboratory preparation of hydrogen from zinc and dil. acid. Give reasons for the following :
(a) The complete apparatus is air-tight.
(b) Dilute nitric acid is not preferred as the reactant acid.
(c) The lower end of the thistle funnel should dip below the level of the acid in the flask.
(d) Hydrogen is not collected over air.
Hydrogen
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Answer
(a) Hydrogen forms an explosive mixture with air hence the complete apparatus is air tight preventing any leakage of the gas.
(b) Nitric acid is a strong oxidizing agent, it oxidizes the hydrogen formed to water and hence is not preferred as the reactant acid.
(c) The lower end of the thistle funnel should dip below the level of the acid in the flask, otherwise hydrogen gas produced will escape through thistle funnel.
(d) Hydrogen is collected over water and not air as it forms an explosive mixture with air.
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