Question

The Boiling point of salt water is higher than pure water.
(A) True
(B) False

Answer 1

Hint: Solutes like salts, sugars can easily dissolve in water. While taking the solute from the water and converting it into gas phase requires a lot of energy. These solutes are in the liquid phase at a temperature around the water boiling point. Increasing the boiling point of a solvent by adding a solute refers to the elevation of boiling point.

Complete Answer:
The vapour pressure of the solution decreases when a volatile solute is added to that volatile solvent. There are many properties of solutions depending on this decrease in vapour pressure. Those are,
(i) Relative lowering of the vapour pressure of the solvent
(ii) Depression of freezing point of the solvent
(iii) Elevation of the boiling point of the solvent
(iv) Osmotic pressure
Elevation of the boiling point of the solvent: This is dependent on the solute to the solvent ratio which the elevation in the boiling point of a solution is observed when a solute like saltwater is added to it. The boiling point of water means the temperature at which its vapour pressure is equal to the pressure of its surrounding environment. When a non-volatile solute like saltwater is added to the solvent, the resulting solution is lower than that of the pure solvent. Therefore, a greater amount of heat is required for water to boil. This increasing the boiling point of the saltwater than the pure water is the elevation of boiling point.

Hence, the given statement is true.

Note: All of these properties mentioned are known as colligative properties which are the number of solute particles irrespective of their nature related to the total number of particles present in the solution. These properties are used to determine the molar mass of the solutes.