I have a hot air balloon that has 18.0 g helium gas inside of it. if the pressure is 2.00 atm and the temperature is 297k, what is the volume of my balloon?

M = molar mass of the helium gas = 4.0 g/mol

m = mass of the gas given = 18.0 g

n = number of moles of the gas

number of moles of the gas is given as

n = m/M

n = 18.0/4.0

n = 4.5 moles

P = pressure = 2.00 atm = 2.00 x 101325 Pa = 202650 Pa

V = Volume of balloon = ?

T = temperature = 297 K

R = universal gas constant = 8.314

Using the ideal gas equation

P V = n R T

(202650) V = (4.5) (8.314) (297)

V = 0.055 m³

The volume of balloon is 54.86 L

calculation

The volume is calculated using the ideal gas equation

That is PV=nRT

where,

p = 2.00 atm

V=?

n (number of moles) which is calculated as below

moles = mass / molar mass = 18.0g / 4 g/mol = 4.5 moles

R (gas constant) = 0.0821 L. atm / mol. K

T (Temperature) = 297 K

make V the subject of the formula by diving both side by P

V = nRT/P

V = { (4.5 moles x 0.0821 L. atm/mol. K x 297 K) / 2.00 atm} = 54.86 L