Question

In a calorimeter of water equivalent $20 \,g$, water of mass $1.1\, kg$ is taken at $288\, K$ temperature. If steam at temperature $373 \,K$ is passed through it and temperature of water increases by $6.5^{\circ} C$ then the mass of steam condensed is

• A. 17.5 g
• B. 11.7 g
• C. 15.7 g
• D. 18.2 g

Answer 1

Answer: (B)

Let mass of steam that gets condenced while the temperature of water is raised by $6.5^{\circ} C =x g$
So, heat released by steam $=540 x \,cal +x \times 1 \times 78.5$
$[Q=m L+m s \Delta T]$
This heat goes to the water + calorimeter system
$Q$ required by water $=1100 \times 1 \times 6.5=7150\, cal$
$Q$ required by calorimeter $=20 \times 1 \times 6.5=130 \,cal$
$Q_{\text {released }}=Q_{\text {required }}$
$78.5 x+540 x=7150+130$
$x \simeq 11.7 \,g$