When solid sodium bicarbonate is added to a dilute aqueous solution of ethanoic acid

Carbon and its Compounds

Chemical Properties of Carbon Compounds

Options

(A)Brisk effervescence takes place and an odourless gas is evolved.

(B)Brisk effervescence takes place and a pungent smelling gas is evolved.

(C)No effervescence occurs and no gas is evolved.

(D)Brisk effervescence occurs and a gas is evolved which helps a glowing splinter to burn with a flame.

Official Answer

Brisk effervescence takes place and an odourless gas is evolved.

brisk effervescenceodourless gascarbon dioxideCO2sodium bicarbonate

Marking Scheme

11 mark for selecting the correct option (A).

Hint

Recall the reaction between an acid and a metal hydrogen-carbonate mentioned in the text context of carbon forms.

Quick Oral Answer

The gas evolved is carbon dioxide ( $CO_2$ ). It can be tested by passing it through lime water, which turns milky.

Analysis & Explanation

When ethanoic acid (acetic acid, $CH_3COOH$ ) reacts with sodium bicarbonate ( $NaHCO_3$ ), a neutralization reaction occurs that releases carbon dioxide gas ( $CO_2$ ). The reaction is: $CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + H_2O + CO_2 \uparrow$ . The rapid evolution of $CO_2$ causes 'brisk effervescence'. Carbon dioxide is a colourless and odourless gas, making Option A correct. Option B is wrong because $CO_2$ is not pungent. Option C is wrong because a reaction definitely occurs. Option D is wrong because $CO_2$ does not support combustion; it would actually extinguish a glowing splinter.

Common Mistakes

1Identifying the gas as oxygen which supports combustion.
2Confusing the odourless CO2 with pungent gases like SO2 or NH3.

Interesting Facts

This reaction is the basis for the 'volcano' experiment often performed in school science fairs.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2011?

This question carries 1 mark in the CBSE Class 10 Science 2011 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Carbon and its Compounds" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Chemical Properties of Carbon Compounds" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2011 paper?

This is a MCQ question from Section B in the CBSE Class 10 Science 2011 paper.