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Question
Identify the gas evolved and give the chemical test in the following case:
Dilute hydrochloric acid reacts with sodium sulphite.
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Solution
Gas Evolved: When dilute hydrochloric acid reacts with sodium sulphite, the gas evolved is sulphur dioxide.
Reaction:
\[\ce{Na2SO3 + 2HCl -> 2NaCl + H2O + SO2 ^}\]
Chemical Test for sulphur dioxide: Pass the gas through an acidified potassium dichromate (K2Cr2O7) solution.
Observation: The solution changes color from orange to green due to the reduction of chromium from Cr6+ to Cr3+.
\[\ce{SO2 + H2O + K2Cr2O7 + H2SO4 -> Cr2(SO4)3 + K2SO4 + H2O}\]
RELATED QUESTIONS
In the contact process for the manufacture of sulphuric acid give the equations for the conversion of sulphur trioxide to sulphuric acid.
Give two balanced reactions of the type to show the following property of sulphuric acid:
Acidic nature
Name the following:
The precipitate obtained by treating aqueous barium chloride with dilute sulphuric acid.
Name the following:
The precipitate obtained by treating carbon with hot concentrated sulphuric acid.
What would you observe in the following case?
Dilute sulphuric acid is added to ferrous sulphate solution.
Give reason for the following:
Concentrated sulphuric acid should not be added to oxalic acid or formic acid in the open laboratory.
How are the following conversion brought about? Give equation and condition:
Sucrose to sugar charcoal.
What do you observe when barium chloride solution is added to dilute sulphuric acid ?
Write balanced equation for the reaction of dilute sulphuric acid with the following:
Zinc hydroxide
Hydrogen chloride gas is prepared in the laboratory by the action of concentrated sulphuric acid on sodium chloride.
Give a balanced chemical equation for the above reaction.
