## Molecules in a Flask of Air

A flask that appears to be empty can actually be filled with a mixture of gases called air. If the flask volume is 3.00 L and the air is at standard temperature and pressure, the number of gaseous molecules it contains can be calculated using the Ideal Gas Law.

## Ideal Gas Law

The Ideal Gas Law states that the pressure of a gas is proportional to the number of molecules of the gas and the temperature of the gas. The equation for the Ideal Gas Law is PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

## Calculating the Number of Molecules

To calculate the number of molecules in a volume of air, we must first calculate the number of moles. To do this, we can use the Ideal Gas Law equation to solve for n. We know that the pressure and volume are 3.00 L and that the temperature is at standard temperature and pressure, so we can solve for n. n=PV/RT, where n is the number of moles, and R is the ideal gas constant. Once we have the number of moles, we can calculate the number of molecules by multiplying the number of moles by Avogadro’s number, which is 6.022 x 1023 mol-1.

## Related Questions

• What is the Ideal Gas Law?
• What is the temperature for standard pressure and temperature?
• How do you calculate the number of moles in a sample?