Question

Helium gas has a volume of 18.5 L and 85.5 KPa and 296 K what is the mass of a helium under these conditions

Answer 1

2.572 g

Step-by-step explanation:

From the question;

Volume of Helium gas, V is 18.5 L

Pressure,P is 85.5 kPa

Temperature, T is 296 K

We are required to calculate the mass of Helium gas

Step 1: Calculate the number of moles of Helium gas

• This can be done using the ideal gas equation.
• The ideal gas equation is PV=nRT, where P is the pressure, V is the volume, n is the number of moles, T is the temperature and R is the ideal gas constant which is 8.314 kPa.L/K.mol

Rearranging the formula;

`n=(PV)/(RT)`

Thus,
`n=((85.5kPa)(18.5L))/((8.314)(296K))`

`n=0.6427`

n = 0.643 moles

Therefore, moles of Helium are 0.643 moles

Step 2: Calculate the mass of Helium gas

To calculate the mass we multiply the number of moles by the molar mass.

Mass = Number of moles × Molar mass

Molar mass of Helium = 4.00 g/mol

Therefore;

Mass of He = 0.643 moles × 4.00 g/mol

= 2.572 g

Hence, mass of helium gas is 2.572 g