Question

An organic compound with molecular formula ${{\text{C}}_{\text{2}}}{{\text{H}}_{\text{4}}}{{\text{O}}_{\text{2}}}$ produces brisk effervescence on addition of sodium carbonate/bicarbonate.
Identify the organic compound.
A) Name the gas evolved.
B) How will you test the gas evolved?
C) Write the chemical equation for the above reaction.
D) List two important uses of the above compound.

Answer 1

Hint: To solve this we must first identify the organic compound with the molecular formula ${{\text{C}}_{\text{2}}}{{\text{H}}_{\text{4}}}{{\text{O}}_{\text{2}}}$. We must know the gas that produces brisk effervescence and how do we test the gas.

 Complete step by step answer:
We are given an organic compound with molecular formula ${{\text{C}}_{\text{2}}}{{\text{H}}_{\text{4}}}{{\text{O}}_{\text{2}}}$. The compounds reacts with sodium carbonate or sodium bicarbonate and produces brisk effervescence.
The organic compound with molecular formula ${{\text{C}}_{\text{2}}}{{\text{H}}_{\text{4}}}{{\text{O}}_{\text{2}}}$ is acetic acid. The molecular formula for acetic acid is ${\text{C}}{{\text{H}}_{\text{3}}} - {\text{COOH}}$.

Acetic acid on reaction with sodium carbonate or sodium bicarbonate produces a gas. The gas is evolved with brisk effervescence. When acetic acid reacts with sodium carbonate or sodium bicarbonate carbon dioxide gas is produced. The molecular formula for carbon dioxide is ${\text{C}}{{\text{O}}_{\text{2}}}$.
The evolved carbon dioxide gas when passed through lime water, turns lime water milky. Thus, the evolved carbon dioxide gas can be tested by passing through lime water. If the lime water turns milky, carbon dioxide gas is confirmed.

The reaction of acetic acid with sodium carbonate produces sodium salt of acetic acid. Along with it carbon dioxide gas and water is produced. The reaction of sodium carbonate with acetic acid is as follows:
${\text{2C}}{{\text{H}}_{\text{3}}}{\text{COOH}} + {\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} \to {\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}} + {\text{C}}{{\text{O}}_{\text{2}}} + {{\text{H}}_{\text{2}}}{\text{O}}$

The reaction of acetic acid with sodium bicarbonate produces sodium salt of acetic acid. Along with it carbon dioxide gas and water is produced. The reaction of sodium bicarbonate with acetic acid is as follows:
${\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} + {\text{NaHC}}{{\text{O}}_{\text{3}}} \to {\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}} + {\text{C}}{{\text{O}}_{\text{2}}} + {{\text{H}}_{\text{2}}}{\text{O}}$
The uses of acetic acid are as follows:
1-Acetic acid is used as vinegar. Vinegar is mostly used in cooking.
2-Acetic acid is used in preservation of pickles, etc.

Note: The reaction of carbon dioxide gas with lime water i.e. calcium hydroxide produces calcium carbonate and water. The calcium carbonate is a white precipitate which appears milky. The reaction is as follows:
${\text{C}}{{\text{O}}_{\text{2}}} + {\text{Ca}}{\left( {{\text{OH}}} \right)_{\text{2}}} \to {\text{CaC}}{{\text{O}}_{\text{3}}} + {{\text{H}}_{\text{2}}}{\text{O}}$.