Question

Steam at ${100}^{\circ }C$ is passed into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at ${15}^{\circ }C$ till the temperature of the calorimeter and its contents rises to ${80}^{\circ }C$. The mass of the steam condensed in kg is

• A. 0.130
• B. 0.065
• C. 0.260
• D. 0.135

Answer 1

The correct option is A

0.130

Heat is lost by steam in two stages (i) for change of state from steam at ${100}^{\circ }C$ to water at ${100}^{\circ }C$ is m × 540
(ii) to change water at ${100}^{\circ }C$ to water at ${80}^{\circ }C$ is
m × 1 × (100 - 80), where m is the mass of steam condensed.

Total heat lost by steam is m × 540 + m × 20 = 560 m (cals) Heat gained by calorimeter and its contents is

= (1.1 + 0.02) × (80 - 15) = 1.12 × 65 cals.

using Principle of calorimetery, Heat gained = heat lost

\ 560 m = 1.12 × 65, m = 0.130 gm