Question

A 2.50 L flask was used to collect a 5.65g sample of propane gas $C_{3}H_{8}$. After the sample was collected, the gas pressure was found to be 956 mmHg. What was the temperature of the propane in the flask?

Answer 1

From the given,

Mass of sample (propane) = 5.65 g

Pressure = 956 mm Hg

Let's convert pressure mm Hg into atm.

$P\quad =\quad \frac { 956 }{ 760 } \quad atm\quad =\quad 1.26\quad atm$

Volume = 2.50 L

Molar mass of Propane = ${ C }_{ 3 }{ H }_{ 8 }$  = 44 g/ mol

According to the ideal gas,

$PV\quad =\quad nRT\\ \\ T\quad =\quad \frac { PVM }{ mR } \\\\ =\quad \frac { 1.26\quad atm\quad \times \quad 2.50\quad L\quad \times \quad 44\quad g/mol }{ 5.65\quad g\quad \times \quad 0.0821\quad L\quad atm.\quad mo{ l }^{ -1 }{ K }^{ -1 } } \\ \\T\quad =\quad 298.8\quad K$

Therefore, total temperature of the propane in flask is 298.8 K