If I have an unknown quantity of gas at a pressure of 380 mmHg, a volume of 25 L, and a temperature of

300° K, how many moles of gas do I have?

0.5077 moles

Explanation:

Data Given:

Moles = n = ?

Temperature = T = 300 K

Pressure = P = 380 mmHg = 0.50 atm

Volume = V = 25 L

Formula Used:

Let's assume that the hydrogen gas in balloon is acting as an Ideal gas, the according to Ideal Gas Equation,

P V = n R T

where; R = Universal Gas Constant = 0.082057 atm. L. mol⁻¹. K⁻¹

Solving Equation for n,

n = P V / RT

Putting Values,

n = (0.50 atm * 25 L) / (0.082057 atm. L. mol⁻¹. K⁻¹ * 300 K)

n = 0.5077 moles