# Density of Gas Formula

## What is the Density of Gas?

Density is defined as mass per unit volume of a substance under specific conditions of temperature and pressure. The density of gas is equal to its mass divided by the volume. You can calculate the molar mass of the substance once the density of gas is known. The Density varies with temperature and pressure.
If density is expressed in moles per liter, Density of gas formula is mathematically expressed as

$\dpi{120}&space;\large&space;d=\frac{n}{V}=\frac{P}{RT}=P(\frac{MW}{RT})$

Where in,

P is the pressure of gas

V is the volume of gas

n is the amount of gaseous substance in moles

R is the universal gas constant

T is the temperature of the gas

### Example 1

A 564.3 ml volume of chlorine at 27oC and 740 torr has a mass of 1.607g. Determine the density of chlorine.

Solution

Reduce the volume to standard conditions.

V2 = 564.3 x 273 K/300 K x 740 torr/760 torr

= 500 mL

The mass of chlorine is not changed

x/1 mL = 1.607/ 500mL

x =  0.003214 g/mL

Hence, the density of Chlorine is 0.003214 g/mL

Example 2

Determine the density of SO2 gas at 40oC and 730 mmHg.

Solution

The molecular weight of SO2 is 64 g/mol. Substituting in the corresponding equation, we get

D = P(MW) / RT

D = 730 x 64 / 62.4 x 313K

= 2.39 g/L

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