Question

Write T for true and F for false statements.

When common salt dissolves in water, heat is evolved.

• A. True
• B. False

Answer 1

The correct option is B False

Exothermic changes:

1. When a chemical change takes place with the release of energy, it is called an exothermic change.
2. Energy can be released in the form of light or heat.
3. Example of exothermic change: burning of woods, Combustion, Freezing of water.

Dissolving common salt (Sodium Chloride/NaCl) in water is an endothermic change because:

• It takes energy to separate the ions (${\mathrm{Na}}^{+},{\mathrm{Cl}}^{-}$) from one another.
• The system absorb heat from the surrounding in order to proceed the dissolution.
• The temperature of solution of salt in water is little lower than the temperature of pure water.

Thus, the given statement is false.