Question

A gas has a volume of 31.2 L at a temperature of 28 degrees Celsius and a pressure of 82.6 kPa. How many moles are in the sample of gas?
Under what conditions do gases deviate from ideal behavior?
high pressure and high temperatures
high pressure and low temperatures
low pressure and low temperatures
low pressure and high temperatures

Answer 1

1.02 moles of the gas is present in the sample.

The conditions in which the gases deviate from ideal behavior is high pressure and low temperatures.

Correct option is 2.

Explanation:

Data given:

volume of the gas = 31.2 litres

temperature of the gas = 28 degrees or 301.15 K

pressure of the gas = 82.6 kPa or 0.815 atm

R (Gas constant) = 0.0820 Latm/moles K

number of moles =?

From the ideal gas law, we have

PV = nRT

rearranging the equation:

n = $\frac{PV}{RT}$

n = $\frac{0.815 X 31.2}{301.15 X 0.0820}$

n = 1.02 moles

At high pressure and low temperature an ideal gas deviates from ideal behaviour. Under high pressure the gas molecules get closer to each other and intermolecular force acts on them as molecules attract each other while in ideal case gas has no attractions in its molecules.