Question

A gas with effervescence is evolved when pinch of sod.carb.is added to ethanoic acid

Answer 1

Carbon dioxide is the gas that is evolved with an effervescence when a pinch of sodium carbonate is added to ethanoic acid.

The equation for this reaction is - 

CH₃COOH + Na₂CO₃ → CH₃COONa + H₂O + CO₂

Ethanoic acid reacts with Sodium carbonate to form Sodium Ethanoate, water, and releases Carbon dioxide gas.

A strong effervescence due to the evolution of carbon dioxide confirms the presence of a carboxylic group. When this evolved CO2 gas is passed through lime water, it turns milky.

Answer 2

The answer of your question is " Carbon dioxide( CO2)"  

When a pinch pf sodium carbonate is added to ethanoic acid carbon dioxide gas is released with the effervescence . This reaction result in the production of sodium ethanoate and water also.And due to release of carbon dioxide (Being gas) a effervescence can also be observed 

The reaction will be like CH3COOH + Na3CO3⇒CH2COONa + H2O + CO2 

 

Hope this will help you in your study