Question

Steam at $100^{\circ }C$ is passed into $1.1kg$ of water contained in a calorimeter of water equivalent $0.02kg$ 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

Answer: (A)

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 $m\times 540$
(ii) to change water at $100^{\circ }C$ to water at $80^{\circ }C$ is $m\times 1\times (100$ $80)$,
where $m$ is the mass of steam condensed.
Total heat lost by steam is $m\times 540+m\times 20=560m$ (cals) Heat gained by calorimeter and its contents is
$=(1.1+0.02)\times (80-15)=1.12\times 65$ cals.
using Principle of calorimetery, Heat gained = heat lost
$\therefore 560m=1.12\times 65m=0.130gm$