Question

A 12​-liter ​[l] flask contains 1.3 moles​ [mol] of an ideal gas at a temperature of 20 degrees celsius ​[degrees​c]. What is the pressure in the flask in units of atmospheres​ [atm]

Answer 1

Given: Volume of flask=12 L

Number of moles of an ideal gas=1.3 mol

Temperature=20°C

Gas is an ideal gas thus, it follows the ideal gas equation as follows:

$PV=nRT$

Here, P is pressure, V is volume, n is number of moles, R is Universal gas constant $0.0821 atm L K^{-1} mol^{-1}$ and T is temperature.

First convert temperature from °C to K as follows:

$0 ^{o}C=273.15 K$

Thus,

$20 ^{o}C=293.15 K$

Rearrange ideal gas equation to calculate pressure,

$P=\frac{nRT}{V}$

Putting the values,

$P=\frac{(1.3 mol)(0.0821 atm L K^{-1}mol^{-1})(293.15 K)}{(12 L)}=2.6 atm$

Therefore, pressure in the flask will be 2.6 atm.