Question

In an experiment to study the properties of ethanoic acid, a student takes about 3 mL of ethanoic acid in a dry test tube. He adds an equal amount of distilled water to it and shakes the test tube well. After some time he is likely to observe that

• A. A colloid is formed in the test tube
• B. The ethanoic acid dissolves readily in water
• C. The solution becomes light orange
• D. Water floats over the surface of ethanoic acid

Answer 1

The correct option is B

The ethanoic acid dissolves readily in water

Ethanoic acid: Ethanoic acid (CH₃COOH) belongs to the group of Carboxylic acids and is commonly called Acetic acid.

1. After adding 5-8% of Acetic acid to water it becomes vinegar and is mostly used as a preservative in pickles.
2. Because it does not release all of its hydrogen in water, ethanoic acid (acetic acid) is classified as a weak acid. Instead, it dissociates partly and achieves equilibrium with its conjugate base.

Explanation for Correct answer:

When 3 ml of Ethanoic acid adds an equal amount of distilled water to it:

1. Ethanoic acid is a typical weak acid.
2. It reacts with water to produce Hydroxonium ions and Ethanoate ions, but the back reaction is more successful than the forward one.
3. The ions react very easily to reform the acid and the water.
4. The chemical reaction is:$\underset{\mathrm{Ethanoic}\mathrm{acid}}{{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{l}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}}\stackrel{}{\left(\mathrm{l}\right)\to }\underset{\mathrm{Ethanoate}\mathrm{ion}}{{\mathrm{CH}}_3{\mathrm{COO}}^{-}\left(\mathrm{l}\right)}+\underset{\mathrm{Hydronium}\mathrm{ion}}{{\mathrm{H}}_3{\mathrm{O}}^{+}\left(\mathrm{l}\right)}$

Final answer: Hence, the correct option is (b). Ethanoic acid readily dissolves in water to form vinegar.