Question

A bulb with chlorine gas at ambient pressure contains 3.55 g at t${}^o$C. When the bulb is placed in a second thermostat at a temperature 30${}^o$C higher and the stopcock of the bulb temporarily opened (and closed again) to restore the initial pressure, the bulb is now found to contain 3.2 g of chlorine. What is the value of t${}^o$C?

• A. 2.81${}^o$C
• B. 8.21${}^o$C
• C. 8.12${}^o$C
• D. 1.28${}^o$C

Answer 1

The correct option is D 1.28${}^o$C

As we know the gas equation for an ideal gas is $PV=nRT$

As given in the initial and final pressure is maintained same so,

$\frac{n_{1}R{T}_1}{V_1}=\frac{n_{2}R{T}_2}{V_2}$

As the container remains the same hence initial volume and final volume will be the same

So,

As initial temperature $=t+273K$

final temperature $=t+30+273K$

Now,

$\frac{3.55\times (t+273)}{35.5}=\frac{3.2\times (t+303)}{35.5}$

$3.55t+(3.55\times 273)=3.2t+(3.2\times 303)$

$0.35t=3.2\times 303-3.55\times 273$

$0.35t=969.6-969.15$

$t=\frac{0.45}{0.35}=1.28$${}^{o}C$