Question

An organic compound 'P' is a constituent of wine. 'P' on reacting with acidified K₂Cr₂O₇ forms another compound 'Q'. When a piece of sodium is added to 'Q', a gas 'R' evolves which burns with a pop sound. Identify P, Q and R and write the chemical equations of the reactions involved. (Bored Term II Foreign Set-I, 2016)

Answer 1

Tartaric acid (P) reacts with acidified potassium dichromate (Q) to form potassium hydrogen tartrate (Q), which, on reacting with sodium (R), produces carbon dioxide gas (R).

Step-by-step explanation:

The organic compound 'P' that is a constituent of wine is tartaric acid (H₂C4H4O6). When 'P' reacts with acidified potassium dichromate (K₂Cr₂O₇), it forms another compound 'Q'. On adding a piece of sodium to 'Q', a gas 'R' evolves which burns with a pop sound. 'P' is tartaric acid, 'Q' is potassium hydrogen tartrate (KHC4H406), and 'R' is carbon dioxide gas (CO₂).

The reactions involved can be represented as:

Reaction 1:

tartaric acid (P) + acidified potassium dichromate (Q) → potassium hydrogen tartrate (Q) + other products

Reaction 2:

potassium hydrogen tartrate (Q) + sodium (R) → carbon dioxide gas (R) + other products