What is the mole fraction of each gas in the mixture described in Problem 9.77?

Name: Problem 78, Chapter 9: Chemistry
Uploaded: 2020-05-07T18:56:11-08:00
Duration: 5 min 25 s
Channel: Jason Boomer
Description: What is the mole fraction of each gas in the mixture described in Problem 9.77?

What is the mole fraction of each gas in the mixture...

Key Concepts

Partial Pressure

Partial pressure is the pressure exerted by an individual gas in a mixture as if it occupied the entire volume alone. It is directly related to the mole fraction of that gas in the mixture, which makes it a fundamental concept when working with gas mixtures and applying the ideal gas law.

Ideal Gas Law

The ideal gas law, expressed as PV = nRT, relates the pressure, volume, temperature, and number of moles of a gas. It provides a framework for understanding the behavior of gases under ideal conditions and is essential when calculating properties like mole fractions and partial pressures in gas mixtures.

Mole Fraction

Mole fraction is the ratio of the number of moles of a component to the total number of moles in a mixture. It is a dimensionless quantity that indicates the relative abundance of each component and is key in calculating properties like partial pressure in gas mixtures.

Gas Mixtures

Gas mixtures consist of two or more gases combined into one system. Understanding how these gases interact and their individual contributions—often evaluated through mole fractions and partial pressures—is crucial in predicting the overall behavior of the mixture.

Transcript

00:03 So this question gives us a mixture of gases, and they tell us the percentage by weight of each of the component gases, and they ask us to find the mole fraction.

00:15 So we've got 5 % hydrogen chloride, 1 % hydrogen, and 94 % neon by weight.

00:21 We need to figure out what those are by molar percentage, which means we need to figure out what the relative number of moles of each of them is.

00:32 So we aren't told how much of this gas there is.

00:37 So the easiest way to go about this is to set an arbitrary mass.

00:43 Since we know what they are by weight, we can start by saying, well, we have, what if each percentage is a gram? so we have five grams of hcl.

00:57 We have one gram of h2 and 94 grams.

01:10 Of neon.

01:11 And you could use any number as long as it came out proportionals.

01:14 You could do 10, 2, and 188 if you prefer, or you could do 50 and 10 and 940 if you prefer.

01:23 But i'm just going to use 5 .1 and 94.

01:27 And what i'm going to do is i'm going to use some stoichiometry to convert these to moles.

01:33 So we know that hydrogen chloride, hydrogen is 1 gram per mole, chlorine is 35.

01:40 So it's going to be 36 grams for every one mole.

01:54 For the hydrogen, every one mole is 2 grams because it's h2.