A cylinder of argon gas contains 50.0 L of Ar at 18.4 atm and 127 °C. How many moles of argon are in the cylinder?

1 Answer
Feb 19, 2016

The cylinder contains "28.0 mol Ar".

Explanation:

Use the ideal gas law.

PV=nRT, where n is moles and R is the gas constant.

Known
P="18.4 atm"
V="50.0 L"
T=127^@"C+273.15=400 K"
R="L atm K"^(-1) "mol"^(-1)
https://en.m.wikipedia.org/wiki/Gas_constant

Unknown
n

Solution
Rearrange the equation to isolate n. Substitute the known values into the equation and solve for n.

PV=nRT

n=(PV)/(RT)

n=(18.4cancel"atm" * 50.0cancel"L")/(0.082057338 cancel"L" * cancel"atm" * cancel"K"^(-1) * "mol"^(-1) * 400"K")="28.0 mol Ar"