Question

A colourless organic liquid X of molecular formula C₂H₄O₂ turns blue litmus to red. Another colourless organic liquid Y of molecular formula C₃H₆O has no action on any litmus but it is used as a nail polish remover. A yet another colourless organic liquid Z of molecular formula C₂H₆O has also no action on litmus but it is used in tincture of iodine.

(a) Name the liquid X. To which homologous series does it belong? Give the name of another member of this homologous series.
(b) Name the liquid Y. To which homologous series does it belong? Write the name of another member of this homologous series.
(c) Can you name an organic compound having the same molecular formula as liquid Y but which belongs to a different homologous series? What is this homologous series?
(d) Name the liquid Z. To which homologous series does it belong? Write the name of another member of this homologous series.

Answer 1

(a) The liquid 'X' is ethanoic acid which turns the blue litmus red. It belongs to the homologous series of carboxylic acid. Methanoic acid is the other member of this homologous series.
(b) The liquid 'Y' is propanone which is colourless, and is widely used as a nail polish remover. It belongs to the homologous series of ketones. Butanone is the name of the other member of this homologous series.
(c) Propanal is an organic compound having the same molecular formula as of the liquid 'Y' (Propanone), but the former belongs to the homologous series of aldehydes.
(d) The liquid 'Z' is ethanol which has no action on the litmus, and is used in the tincture of iodine. It belongs to the homologous series of alcohols. Methanol is the other member of this homologous series.