Question

A metal salt MX when exposed to light splits up to form metal M and a gas X₂. Metal M is used in making ornaments whereas gas X₂ is used in making bleaching powder. The salt MX is itself used in black and white photography.

1. What do you think metal M is?
2. What could be gas X₂?
3. Name the metal salt MX.
4. Name any two salt solutions which on mixing together can produce a precipitate of salt MX.
5. What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of the reaction.

Answer 1

1. Metal M is silver (Ag). Silver is a highly lustrous, precious metal used for making ornaments and jewellery.
2. The gas X₂ is chlorine (Cl₂). Chlorine gas is a key chemical used in the manufacturing of bleaching powder.
3. Silver chloride (AgCl)
4. Mixing Silver nitrate (AgNO₃) and sodium chloride (NaCl) solutions will produce an insoluble, white precipitate of silver chloride (MX).
5. Exposing the salt to light results in a photolytic decomposition reaction (or photolysis).
   \[\ce{2AgCl_{(s)} ->[Light] 2Ag_{(s)} + Cl2_{(g)}}\]