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Gas Pressure Conversions

Feb 22, 2020
In a previous lesson we saw how we can use units like millimeters of mercury or millimeters of water to measure gas

pressure

, but usually when we measure things there are many different units that we can use and support to understand how to interconvert them to For example, if I am measuring well the length, you could use centimeters or inches, you could use feet, yards, meters or miles, so in this lesson, which is very short, we're going to look at some common units for measuring gas

pressure

and then we'll see how we can use conversion factors to convert between them.
gas pressure conversions
If you're a little rusty with conversion factors and significant figures, it would be helpful to review those old lessons before doing this just to be sure. that has a firm foundation, so some common gas pressure units you are already familiar with one of them and that is millimeters of mercury. Miller's millimeters of mercury are sometimes also called tours and this is a credit to the Italian scientist Tora Celli who is the first to realize that mercury in a glass tube can be used to measure gas pressure, don't let Let this confuse you, millimeters of mercury Torr, it's the same thing, it's a different name for the same thing, another common gas pressure unit is the atmosphere and this seems a little complicated at first because the atmosphere is also something physical, air that surrounds the Earth, but it is also the name of a unit, so we can have, for example, two point seven atmospheres of pressure.
gas pressure conversions

More Interesting Facts About,

gas pressure conversions...

It's just a unit like pounds, miles, inches or whatever. and the third unit is called kilopascal, this is also named after a scientist Pascal who worked a lot on force and pressure etc., there are abbreviations for these millimeters of mercury and runs. These are already abbreviated atmospheres that we can abbreviate as atm in kilo Pascal is abbreviated as lowercase K, uppercase P and lowercase a. In order to do a mathematical conversion between these types, we have to have some kind of equation that explains how they all relate, so here we can say that 760 millimeters of mercury or 760 torr for such a person is equivalent to 180 M, which is equivalent to one hundred 1.3 kilos Pascal.
gas pressure conversions
There are three different things in this equation, but don't let it confuse you, just as 760 millimeters of mercury equals 1 atm, this also means that 760 millimeters of mercury equals 100 and 1.3 kilo Pascals, as we did earlier in problems From conversion factors above, we'll use this equation to write conversion factors to go between these different units depending on which one we want to start with or which one we want to end with, so let's get some hands-on experience with conversion from these guys solving this problem. The pressure inside car tires is 225 kilos. Pascal expresses this value in both ATM and millimeters of mercury.
gas pressure conversions
First we will do atmospheres, as you remember from the conversion factors. We always want to write conversion factors before starting the problem. We start here with 225 kilo Pascal and we want to multiply it by something that will give us a new answer, so we are converting from kilo Pascal to. atmospheres there are two conversion factors that we can write, the first will be 1 atm and therefore it is equivalent to 100 and 1.3 kPa, that is a conversion factor, another conversion factor that we can write is the same, but it is inverted so we can write 101.3 kPa divided by 1 atm, both are perfectly good, but which one do we want to use?
Remember when we do a conversion factor what we want to do is end up canceling the old units and end up with new units we can only cancel units if the unit is up on one side and is down on the other side so we will use this conversion factor conversion because kPa is obviously up here and it's at the bottom down here this is the one we're going to use so we're going to say 2 25 kPa times 180 m / 101 point 3 kPa since kPa is at the top here in the bottom here these guys are going to cancel and we're going to go ahead and do our calculations.
Remember that the final calculations will be this multiplied by this divided by this and my final answer will be two point two two, the reason I round that up. to three significant figures is there are three numbers here three digits here three significant figures four significant figures here there is one here but this is a definition this is an integer so we don't worry about this we ignore it this we take obviously, the smallest of the two, three or four, and we choose one with three, so our final answer has three significant figures. Now, what are the final answers?
Well, kPa canceled out, so we're left with ATMs, which means our final answer will be 2.2 at ATM 2.2 at ATM is our final answer. If the method I use to cancel units and make significant figures at the end, if this confuses you, it is important to go back and look at the previous units that provided information about this because I am worried that you will get confused, otherwise let's look at another example. We made kPa 2 atmospheres. Now let's go from kPa to millimeters of mercury again. We will start with 225 kilos Pascal and multiply it by conversion. factor as before, there are two valid conversion factors that we could write: the first is 760 millimeters of mercury over 100 and 1.3 kilos Pascal, that is a possible conversion factor or again we can invert it, we can say that 100 and 1.3 Pascal kilos are equal to and therefore written more than 760 millimeters of mercury.
Now again we want to choose a conversion factor that cancels out these kPa. We can only cancel the KPA if it is at the top. Here it is at the bottom of the conversion factor, which means that once again. This is the conversion factor we're going to use because kPa is on the bottom 225 kPa multiplied by 760 millimeters of mercury divided by 101 point three kPa. Do we configure it correctly? We did it because KP is up here and at the bottom. down here, which means they cancel out our final units, the only ones left will be millimeters of mercury, so I do it with a calculator, it's a little more difficult, I remember 225 times 760, the answer to that divided by a hundred and 1, 3 kPa the final answer I get is one six nine zero millimeters of mercury obviously the answer I get for this is much longer but there are only three significant figures in this number, we don't worry about the significant figures in this one because the smallest one is three, which means I'm going to round this up to one, six, nine zero millimeters of mercury and that's my final answer, so converting between these different units of gas pressure isn't that difficult, just remember to choose the right conversion. . factor so that your old units are canceled and you get your new unit this expression right here 760 millimeters of mercury equals blah, blah, blah, blah, blah, blah, usually it will always be given to you by the teachers who will appear in the exams. be in the textbook, so it's probably not something you need to memorize, only memorize it if your teacher tells you it's absolutely necessary, otherwise they'll usually always give it to you.

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