download the exercise with solution: ideal gas law

A bottle with volume 3 m³ is filled with oxygen gas. Its temperature is 20°C and pressure equals 1.45 bar. The molar mass of oxygen is M=32 g/mol. Oxygen gas here is assumed to be ideal gas. Please determine:

1)   the mass of gas in bottle;

2)   the number of oxygen gas molecules.

Solution:

1) We first determine the specific gas constant for oxygen gas:

where R=8.314 J/mol∙K is the universal gas constant.

Then we calculate the gas mass through the ideal gas law:

2) We should first calculate the mole of gas in bottle: n=m/M Here N_A is Avogadro constant and equals 6.022∙10²³mol^-1