List two observations which you make when you add a pinch of sodium hydrogen carbonate to acetic acid in a test tube. Write chemical equation for the reaction that occurs.

Q: List two observations which you make when you add a pinch of sodium hydrogen carbonate to acetic acid in a test tube. Write chemical equation for the reaction that occurs.

When a pinch of sodium hydrogen carbonate ($NaHCO_3$) is added to acetic acid ($CH_3COOH$), the following observations are made: 1. Brisk effervescence is observed due to the rapid evolution of a gas. 2. A colorless and odorless gas (carbon dioxide, $CO_2$) is evolved, which turns lime water milky. The chemical equation for the reaction is: $$CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + H_2O + CO_2$$

Carbon and its Compounds

Chemical Properties of Carbon Compounds

Official Answer

When a pinch of sodium hydrogen carbonate ( $NaHCO_3$ ) is added to acetic acid ( $CH_3COOH$ ), the following observations are made:

Brisk effervescence is observed due to the rapid evolution of a gas.
A colorless and odorless gas (carbon dioxide, $CO_2$ ) is evolved, which turns lime water milky.

The chemical equation for the reaction is:

$CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + H_2O + CO_2$

brisk effervescencecarbon dioxideturns lime water milkysodium acetate

CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + H_2O + CO_2

Marking Scheme

11 Mark for listing two correct observations (e.g., brisk effervescence, evolution of a colorless/odorless gas that turns lime water milky).
21 Mark for writing the balanced chemical equation with correct formulas: $CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + H_2O + CO_2$

Hint

Think about the reaction between an acid and a metal hydrogen carbonate. What gas is typically evolved, and what does it look like?

Quick Oral Answer

When sodium hydrogen carbonate is added to acetic acid, we observe brisk effervescence due to the evolution of carbon dioxide gas. The chemical equation is: $CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + H_2O + CO_2$ .

Analysis & Explanation

Acetic acid is a weak organic acid. When it reacts with a metal hydrogen carbonate like sodium hydrogen carbonate ( $NaHCO_3$ ), a neutralization-like reaction occurs, producing a salt (sodium acetate), water, and carbon dioxide gas. The rapid release of carbon dioxide gas bubbles is seen as brisk effervescence. This reaction is a characteristic test for carboxylic acids.

Common Mistakes

1Writing the formula of sodium acetate incorrectly as $CH_3COONa_2$ or $NaCH_3COO$ .
2Forgetting to mention 'brisk effervescence' as a key observation.
3Not balancing the equation (though this reaction is self-balanced).

Interesting Facts

This reaction is the chemical basis behind the classic 'school volcano' experiment, where baking soda (sodium bicarbonate) and vinegar (dilute acetic acid) are mixed to produce a foaming eruption of carbon dioxide gas.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2015?

This question carries 2 marks in the CBSE Class 10 Science 2015 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 2015 paper?

This is a Short Answer question from Section B in the CBSE Class 10 Science 2015 paper.