A balloon is filled with 1.00 mole of hydrogen gas. Using the ideal gas law, calculate the volume (𝑉) of the balloon at standard temperature and pressure (STP).

Question

I need help please, like i get confused when setting the Ideal Gas Law.

Answer 1

For this problem, you don't really need the ideal gas law, but since it says to use it, we will.

PV = nRT ... Ideal gas law

P = pressure = 1 atm (standard pressure)

V = volume in liters = ?

n = moles = 1.00

R = gas constant = 0.0821 Latm/Kmol

T = temperature in K = 273K (standard temperature)

Solving for V, we have...

V = nRT/P = (1)(0.0821)(273) / (1)

V = 22.4 L

Anytime you have STP (standard temperature and pressure), 1 mole of an ideal gas = 22.4 L. So, in the above problem we could have simply done 1.00 mol x 22.4 L / mol = 22.4 L (same answer)

Answer 2

The ideal gas law is

PV = nRT

In this case we're trying to solve for the Volume (V), so it becomes

V = nRT/ P

plugging in the given values that becomes

V = (1.00 mol x 0.0821 L*atm/mol*K)(273.15 K) / 1.00 atm = 22.43 L

meaning that the volume of the balloon at STP is 22.43 L