Question

1. a mixture of helium and neon gases has a total pressure of 1.2 atm. if the mixture contains twice as many moles of helium as neon, what is the partial pressure due to neon?

Explanation:

Step1: Let moles of neon be $n$.

Moles of helium is $2n$.

Step2: Calculate mole - fraction of neon.

Mole - fraction of neon $X_{Ne}=\frac{n}{n + 2n}=\frac{n}{3n}=\frac{1}{3}$

Step3: Use Dalton's law of partial pressures.

$P_{Ne}=X_{Ne}\times P_{total}$
$P_{total}=1.2$ atm, so $P_{Ne}=\frac{1}{3}\times1.2$ atm

Answer:

$0.4$ atm