How do you use pV=nRT in chemistry?

The use is Determining the number of moles, and thus the quantity of a gas, at given pressure (P), volume (V) and temperature (T)

Explanation:

The general equation of ideal gases is expressed by the following form:
PV = nRT .................................. (1)

Where P is the pressure of a gas in atm, V is the volume in Liters, R is the universal gas constant (0.082 Lit.atm/mole.K) and T is the temperature in K (Kilven degree). Thus, after the form (1) above, the number of moles, n, of a gas [at specified pressure, volume and temperature] is determined by the following form:
n =$\text{PV"/"RT}$ ......................... (2)
Then the mass (quantity) of a gas will be calculated after the following form:
Mass of gas (grams) = Number of moles (n) x Molecular mass of a given gas ....................... (3)