Question

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?

Answer 1

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

Answer 2

 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