2021-2022 Gases

ChemistryWiki | RecentChanges | Preferences

Since we are starting to get back to pre-pandemic conditions, you will perform demo or "mini-lab" tasks to help you understand the relationship between different parameters/variable with gases. So there will be a demo/task for Boyles Law, Charles' Law and Gay - Lussac's Law (at one time I called it the No Name Law). Hopefully, these demos will give you a "simple physical understanding" of how gas particles behave and the mathematical relationship between gas parameters/variables.

We will first look at the Particle view of Gases including the 4 main parameters/characteristics of gas particles, under General Information on Gases.

General Information on Gases

So now you should know that Gas particles have four parameters (think of the gas particles in a balloon):
a) Volume, volume gas particle occupy not actual size of particle, usually in mL or L (symbol V)
b) Number of gas particles, in number of moles (symbol n)
c) Gas pressure (I think of number of hits on the container wall for all the gas particle in substance), many different unit but atm is most used, (symbol P)
d) Temperature, energy that the gas particle has, ALWAYS in Kelvin temperature scale K, (symbol T): MOST IMPORTANT ONE TO REMEMBER

Now we will start taking a look at Gas calculations. There are "a lot" of gas calculations "out there" so I have found it is best to organize them into different groups. However, all of the equations are derived or comes from the Ideal Gas law (that will be explained below).

Unlike some of the other chemical concepts, for gas calculations, I think it is important to have an overview of all the gas calculations before dealing with any specific gas calculation.

SO the next section deals with Overview. Before you start looking at the Youtube video, I would like to emphasize what I call a Condition. Each condition is a gas (actually a lot of gas particles) that can be describe with the 4 parameters (V,n,P,T). So there are 2 possibilities:
a) 1 Condition problem: this is where one is just describing the gas using the 4 parameters (no action verbs in question/problem
b) 2 Condition problem : this is where one is "doing something" to the gas SO there is the initial condition (Condition 1) and then after you do something (i.e. increasing temp, decreasing volume), you have the new condition (Condition 2). Usually, people use 1 and 2 as subscripts in the equation (see Gas Law Equation sheet below).

Here is a more in-depth overview.

Overview of Gas Calculations

Now we will turn our attention to each law specifically.
Here are all the equations on one page,

To determine the correct mathematical equation to use for the problem you need to answer a few questions (organizational flow chart) about what is going on to the gas particles and their 4 parameters (V,n,T,P):

The below information is organized using the answers to these questions (as section heading and are underlined). The discussion of each law (specific gas condition(s)) will include:

REMEMBER: All Temperatures used in Gas Calculations MUST BE in KELVIN (K) not Celsius or Fahrenheit!!!!!!!

1 Condition Gas Problem (can tell if there is no action verbs in problem)

Ideal Gas Law

2 Condition Gas Problems (See action verbs in problem, expand or decrease,etc)

2 Condition Gas Problem - 2 parameters vary and 2 parameters held constant (the 3 Gas Laws and Avogadro's Hypothesis)

Boyle's Law - P varies indirectly with V @const T & n (Technically one of the 3 Gas Laws)
Particle View of Matter (KMT) explanation: if you keep the Temp,T, (energy/speed each particle has) and number of gas particles (n) the same, as you reduce the size of the container (decrease V), the particles would have to "hit the wall" more often thereby increasing total hits on wall (increase P).

Gay - Lussaic's Law (No Name Law) - T varies directly with P @const V & n (Technically one of the 3 Gas Laws)
Charles' Law - T varies directly with V @const P & n (Technically one of the 3 Gas Laws)

Avogadro's Hypothesis - V varies directly with n @const P & T (Technically NOT one of the 3 Gas Laws)
2 Condition Gas Problem - 3 parameters vary and n (number of moles of particle) constant

Combined Gas Law - Has all 3 Gas Laws above in the equation.
Review Homework

Here is a Animation/simulation to help understand Boyle's, Charle's, and Gay - Lussaic's Law

ChemistryWiki | RecentChanges | Preferences
Edit text of this page | View other revisions
Last edited March 17, 2022 6:27 am (diff)