Find p using this equation PV=nRT

Question

A sample of hydrogen gas, H2, has a volume of 8.5 L at a temperature of 0oC and a pressure of 1.5 atm. Calculate the number of moles present in this gas sample.

Answer 1

PV = nRT ... ideal gas law

The question says "find P" but P is given as 1.5 atm, so we are actually going to find n, moles.

P = pressure = 1.5 atm

V = volume = 8.5 L

n = moles =?

R = gas constant = 0.0821 L-atm/K-mol

T = temperature in K = 0ºC + 273 = 273 K

Solving for n:

n = PV/RT = (1.5 atm)(8.5 L) / (0.0821 L-atm/K-mol)(273K)

n = 0.569 moles = 0.57 moles (to 2 significant figures)