Ideal Gas Law Introduction

So here I have a tank full of gas and these little dots represent some of the gas particles that would be in this tank. I put the arrows here because all these particles are in constant random motion, they are like a bunch of hyperactive little ones. kids bumping into each other all the time hitting the sides of the container and so on, so we have this gas tank, let's think about the characteristics that we could use to describe it, so one of the things we can do is I could tell what its temperature is, The higher the temperature, remember the faster these gas particles move, so temperature is very important when we talk about gas temperature, the temperature of gases should always be reported in Kelvin, so we can say, for example, that the temperature of this type.

Here is 313 Cal and that's how hot these gas particles and the sample are. When you talk about gas, another important characteristic is pressure. With what force do these gas particles bounce off the side of the tank? How much pressure do they put on them? We could measure them with a pressure gauge or something on the top of this tank. We could say: I don't know, the pressure for this is three point one eight atm. Okay, that could be a pressure and something else that I spent a lot of time talking about the volume of gasoline and again I have these letters here that this is how each of these things is abbreviated volume V, the volume of this tank could be something well as ninety five point two liters and finally look at In these particles that I have drawn there is a certain amount of gas that is here and the amount of gas that is abbreviated with the small letter n is usually reported in moles, which is a convenient measurement of how much of something we have.

We could say that the amount of gas in this tank is, I don't know, seven point five volts. Now, whenever we have a gas sample like this, you know, a tank or it's in a balloon or wherever we can describe, we can give. We analyze these various characteristics and it turns out that also for any gas sample, if we know three of these characteristics, we can calculate what the fourth is, all we need to do is know three and to do that we use an equation which is a representation of the law of

ideal

gases and is written as P times V pressure times volume is equal to n the amount of gas times R times T temperature I'll get to our in a second, don't worry for now it will be a number that we know well, so let's say, for example , that we didn't know what pressure was but we still knew the temperature, volume and amount of gas, no big deal, we can take the equation PV equals NRT and rearrange it and divide both sides by V. let's eliminate the V and then we would have P equal to NRT divided by V.

Let's plug in these values ​​and we could determine what the pressure was, or let's say we knew what the pressure of a particular gas sample was, we know the temperature. it wasn't the volume but we didn't know what the amount of gas was we didn't know how much we had we could calculate that fourth characteristic by rearranging the

ideal

gas law for n canceling R and T on one side rearranging solve it for N and then we could enter the pressure, the volume and temperature and we can calculate the amount of gas, in other words, if we know three of these characteristics, we can always calculate what the fourth one is so you can Ask yourself: what is our R?

It's what we call a constant. It is a number that we know in advance and that does not depend on the variables or our property. The R I will use most of the time. videos is 0.0821 liters per atm / Kelvin per mole now notice that this is a fraction that has both the top and a and it is also not just a number but it has units and look at this, the units in our match the units in my problem match with the characteristics that I would be using correctly, so I have leaders here leaders there ATM ATM Kelvin Kelvin and moles moles you always want the units in our to match the units of the characteristics in your ideal gas problem, okay, because I always want you to the units match, there are also different values, although I'm going to use this mainly for the videos I'm making, for example let's say instead of ATM I was using a pressure that was in millimeters of mercury in this case.

I wouldn't like to use this R here. I want to use this R here so that the units match millimeters of mercury here, millimeters of mercury here and the different numbers 62.4, so again that's what I use here, let's say instead of millimeters of mercury. my pressure was given to me in kPa. I would then use this R value to make the unit match. I have kPa here, kPa here and everyone else is the same, so 8.314, as I keep saying in most of the videos, I've been to what I'm going to do. I'm going to use this upper arm with ATM, but your teacher may ask you to use a different r.

It's no big deal, it's probably just because they're giving it to you. problems that have different pressure units and want the pressure units to match, so don't worry at all if you're using one of these other r's. Setting up and solving the ideal gas law is exactly the same no matter which of these r's you use. Using it is just a matter of plugging in a different R at the end, so no matter which one you're using, you should be able to follow all of these lessons and it should all make sense.