Question

What is the volume of 0.20 moles of helium at STP?

Answer 1

The volume of 0.20 moles of helium at STP is 4.5 liters.

Explanation:

Given:

Number of moles  = 0.20 moles

To Find:

The volume of Helium at STP =?

Solution:

According to ideal gas law

PV = nRT

where

P is pressure,  

V  is volume,  

n  is the number of moles  

R  is the gas constant, and  

T  is temperature in Kelvin.

The question already gives us the values for  p  and  T ,because helium is at STP. This means that temperature is  273.15 K  and pressure is  1 atm .

We also already know the gas constant. In our case, we'll use the value of  

0.08206 L atm/K mol  since these units fit the units of our given values the best

On substituting these values we get

$1 atm \times V = 0.20 moles \times 0.08206 L atm/K mol$

$V = \frac{0.20 moles \times 0.08206 L atm/K mol }{ 1 atm}$

$V = \frac{4.482}{1}$

V =  4.5 Liters