Calculate the volume occupied by 16.5 of methane @STP

Question

Calculate the volume occupied by 16.5 g of methane at STP

Answer 1

One mole of an ideal gas will occupy a volume of 22.4 liters at STP. Standard Temperature and Pressure, "STP" is 0°C (273.15 K) and one atmosphere pressure (101,325 Pa). You can plug these into the Ideal Gas Law to solve for which ever quantity is being varied.

 

Ideal Gas Law

PV = nRT

 

In this problem, you're  given mass and must find volume. So first calculate the mole of ideal gas you have. I will assume that's supposed to be 16.5 grams. Make sure to always include units in the questions and solutions.

 

16.5 g CH₄

Molecular weight of methane = 1*(12 g/mol C) + 4*(1 g/mol H) = 16 g/mol CH₄

 

(16.5 g)/(16 g/mol) = 1.03 mol methane

 

That's pretty close to 1 mole which coincides with our other STP conditions so the solution will be very close to 22.4 L

At STP the Ideal Gas Law can be written as;

 

V = 0.022414n

 

by plugging in the values for R, P and T at STP. Volume is in cubic meters (mL)

 

V = 0.022414(1.03 mol methane) = 0.02311 mL

0.02311 mL * 1000mL/L = 23.1 L Methane