Question

To prevent air from interacting with highly reactive chemicals, noble gases are placed over the chemicals to act as inert “blanketing” gases. A chemical engineer places a mixture of noble gases consisting of 5.50 g of He, 15.0 g of Ne, and 35.0 g of Kr in a piston-cylinder assembly at STP. Calculate the Partial Pressure per Gas​

Answer 1

Explanation:

Given parameters:

Mass of He  = 5.5g

Mass of Ne  = 15g

Mass of Kr  = 35g

Pressure at STP = 1atm

Unknown:

Partial pressure per gas = ?

Solution:

Partial pressure is the pressure a gas would exert it alone occupies the container.

 Partial pressure of a gas  = Mole fraction of a gas x Total pressure of mixture

        Number of moles  = $\frac{mass}{molar mass}$

Number of moles of He  = $\frac{5.5}{4}$   = 1.375mole

Number of moles of Ne = $\frac{15}{20}$   = 0.75mole

Number of moles of Kr = $\frac{35}{83.8}$  = 0.42mole

Sum total of moles  = 1.375 + 0.75 + 0.42 = 2.54moles

Partial pressure of He  = $\frac{1.375}{2.54}$ x 1atm = 0.54atm

Partial pressure of Ne = $\frac{0.75}{2.54}$ x 1atm  = 0.29atm

Partial pressure of kr  = $\frac{0.42}{2.54}$ x 1atm = 0.17atm