Question

At $25^{\circ}C$ and $760\, mm\, Hg$ pressure a gas occupies $600\, mL$ volume. What will be its pressure at a height where temperature is $10^{\circ}C$ and volume of the gas is $640\, mL$?

• A. $576.6$ mm Hg
• B. $676.6$ mm Hg
• C. $777.7$ mm Hg
• D. $667.8$ mm Hg

Answer 1

Answer: (B)

$P_{1} = 760$ mm Hg, $V_{1} = 600 mL$
$T_{1} = 25 + 273 = 298 K$
$V_{2} = 640$ mL and $T_{2} = 10 + 273 = 283 K$
According to combined gas law,
$\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}$
$\Rightarrow P_{2} = \frac{P_{1}V_{1}T_{2}}{T_{1}V_{2}}$
$\Rightarrow P_{2} = \frac{760\left(mm Hg\right) \times\left(600 mL\right) \times\left(283 K\right)}{\left(640 mL\right) \times\left(298 K\right)}$
$= 676.6$ mm Hg