Question

state reason for the following
(i) a tarnished copper vessel begins to shine again when rubbed with lemon.
(ii) use of a mild base like baking soda on the honey - bee stung area relief.

Answer 1

1) copper on reacting with air forms a layer of copper carbonate. when we rubbed with lemon, citric acid reacts with copper and form copper citrate. This copper citrate is soluble in water. hence the copper vessel begins to shine.

2) honey bee stings contains methanoic acid in it. when it bites it causes irritation. but when we use baking soda or mild base it neutralises the acid present and hence it gives us relief