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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
Write a balanced chemical equation for the following:
Action of concentrated sulphuric acid on Sulphur.
Write balanced chemical equations to show how SO3 is converted to Sulphuric acid in the contact process.
Give reason for the following:
Concentrated sulphuric acid should not be added to oxalic acid or formic acid in the open laboratory.
Give main difference between drying agent and dehydrating agent.
What would you see, when a crystal of CuSO4.5H2O is placed in concentrated sulphuric acid? Give reason to explain your observation.
A, B, C and D summarize the properties of sulphuric acid depending on whether it is dilute or concentrated. Choose the property (A, B, C or D), depending on which is relevant to each of the preparations (i) to (ii).
A. Dilute acid (typical acid properties)
B. Non-volatile acid
C. Oxidizing agent
D. Dehydrating agent
(i) Preparation of hydrogen chloride.
(ii) Preparation of ethane from ethanol
(iii) Preparation of copper sulphate from copper oxide.
Name the gas evolved in following case:
The gas produced by the action of concentrated sulphuric acid on sodium chloride.
Distinguish between the following pair of compounds using the test given with brackets:
Dilute sulphuric acid and dilute hydrochloric acid (using barium chloride solution)
Name the acid formed when sulphur dioxide dissolves in water.
Name the anion present in the following compound:
Compound D, when warmed with dilute sulphuric acid, gives a gas that turns acidified dichromate solution green.
