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For this year (2020-2021) with Gas Concept, I will simply provide the information and will NOT be doing any demos or labs. At the bottom of this webpage, there is a link to a simulator/animation to better understand the "Gas Laws" (Boyle's, Charle's, and Gay-Lassic Laws).
We will first look at the Particle view of Gasses including the 4 main parameters/characteristics of gas particles, under General Information on Gasses.
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):
- How many Conditions (see above for discussion)?
- 1 Condition, only one equation Ideal Gas Law
- 2 Conditions, how many parameters are being held constant?
- 2 parameters held constant, 2 parameters vary
- 1 parameters held constant (n), 3 parameters vary
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:
- Name of law
- Explanation of law using Kinetic Molecular Theory (KMT or Particle View of Matter)
- Ideal Gas Law and Combined Gas Laws do not have this but have webpages of notes
- Gas Law Equation Sheet (also above) where one can find specific equation(s)
- Example of Expected work
- Youtube video of explanation of concept including expected work
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.
Here is a Animation/simulation to help understand Boyle's, Charle's, and Gay - Lussaic's Law