A mixture of neon and krypton gases at a total pressure of...

A mixture of neon and krypton gases, at a total pressure of 775 mm Hg, contains 1.85 grams of neon and 10.8 grams of krypton. What is the partial pressure of each gas in the mixture? PNe = _____ mm Hg PKr = ______ mm Hg

Transcript

00:02 Hi there.

00:03 In this question, we are trying to find the partial pressures of the two gases that make up this mixture.

00:12 We have neon and we have krypton.

00:16 And we also know the total pressure, but we know the mass of each gas, and we know the total pressure in the container.

00:25 So what we know about gases is that if we have the mold fraction, that is also going to be the pressure fraction.

00:34 So in other words, if i can find the mole fraction, which i can because i have mass of each of these, i can use that mole fraction and determine the partial pressure of each gas by multiplying that mole fraction times the total pressure.

00:49 So that's going to be our plan.

00:51 We're going to convert from grams to moles of each substance so that we can determine the mole fraction, and we'll use the mole fraction of each gas multiplied by the total pressure to give us the partial pressure.

01:10 For each one.

01:14 All right, so that's where we're heading and what we're going to do.

01:17 So first thing is we need to convert each of these to moles.

01:20 We have 1 .85 grams of neon and we have 10 .8 grams of the krypton.

01:33 Well, to convert these from grams to moles, we need to divide each one by its respective molar mass.

01:40 So one mole of neon is 20 .18 grams.

01:45 And remember, molar masses come from the periodic table.

01:50 This gives us 0 .0917 moles of the neon.

02:00 For the krypton, its molar mass is 83 .8.

02:07 0 grams of krypton for every mole of krypton.

02:16 Calculating its moles, we get 0 .1289.

02:22 And i left an extra significant figure here.