Question

A flask having a volume of 250 mL and containing air is heated to 100${}^{\circ }$C and sealed. Then the flask is cooled to 25${}^{\circ }$C, immersed in water, and opened. What volume of water will be drawn back into the flask, assuming the pressure remaining constant?

• A. 55.27 cm³
• B. 63.24 cm³
• C. 72.32 cm³
• D. 50.27 cm³

Answer 1

The correct option is D

50.27 cm³

Let the volume ($V_1$) of the flask be 250 mL

Temperature ($T_1$) = 100 + 273 = 373 K

Flask cooled to temperature $T_2$ = 25 + 273 = 298 K

According to Charles' law,

$\frac{V_1}{T_1}=\frac{V_2}{T_2}$

Hence, the volume $V_2$ at 298 K is $\frac{V_1\times T_2}{T_1}$

Therefore, $V_2$ =$\frac{250\times 298}{273}$= 199.73 $c{m}^3$

Therefore, water drawn back is 250 - 199.73 = 50.27 $c{m}^3$