The Ideal Gas Law: Crash Course Chemistry #12

Gas, it is all around you in space and on Mars. It is dissolved in your blood and in soda. It is everywhere. It is easy to forget that we are immersed in an ocean of gas But he's around all the time, and you can feel it if you wave your arms. Your view will not be attractive while you are feeling it, but you can feel it. Those little particles and atoms here collide with our hands as we move them, Do you feel it? I have good news and bad news about gas, The good news is when she behaves well It is very easy to describe its behavior in theory And experimentally and mathematically.

And the bad news is … it almost never improves behavior The first arithmetic representation of gas behavior He had a link between pressure and volume, In a closed environment, such as inside this balloon When we decrease the size of the balloon, the pressure in the income increases. And if we could somehow expand the balloon The pressure inside the balloon decreases. If I kept pressing on it, the pressure inside could build so much that it explodes. I can't blow it up, it's a very strong balloon. The relationship here is simple, Multiplying pressure and volume we get a constant. As long as the pressure and the amount of gas remain the same, that constant number will remain the same. This is called "Boyle's Law" and it was of great importance in the 17th century. It is also one of the biggest credit miscalculations in history. Robert Boyle was a very rich Englishman who grew up in Ireland. His father was so wealthy that he was paying another family to raise his children.

Probably because he was too busy land administration or something like that. Boyle had a lot of great ideas on science and chemistry. The most important of these ideas, and they are said to be even more important than Boyle's Law Is that chemists should publish their research not based on what they feel is correct. Rather, it is based on theories that are supported by experience. Richard Townley, another Englishman rich but not as rich as Boyle, He became friends with Boyle And tell him about some of his work that would refute the work of one of those chemists Those who depend on their feelings.

Boyle published a study in which he mentioned that work and called it "Townley's hypotheses." But because of Boyle's high academic standing Perhaps for its wealth, it ended up being called "Boyle's Law." But here's the puzzling thing, Experiences that led to the development of this theory Most of it was conducted by Townley family friend and physician, Henry Bauer, And who was not from the aristocracy It is just a working-class world. Bauer was working on publishing a study he would have made thanks to Finder of the relationship between gas pressure and volume, But after Boyle discussed the ideas privately with Townley He published his study first and credited Townley as the only researcher In doing so, he made sure to hide Bauer's contributions. The Henry Bauer Wikipedia page didn't even mention Boyle's Law Until a few weeks ago when I personally added a paragraph about it Supported, of course, by valid citations.

But Boyle's Law is a wonderful law regardless of who thought of it or who was named after it. In a certain amount of gas, at a constant temperature The product of pressure and volume is always equal to the same number. But where does this constant come from? And why is it different depending on the amount of gas at different temperatures? It has been more than a hundred years Before we know the answer to those questions With the help of French Jad Charles And our Italian friend, Amedeo Avogadro.

Charles and Avogadro developed equations similar to Boyle's law It involves directly linking two properties of a gas by means of constants. Charles discovered that volume divided by temperature is equal to a constant Provided the pressure remains the same, Avogadro then concluded that the volume is divided by the number of moles in a container At constant pressure and temperature gives another constant. But here is this wonderful crazy thing, All of these scientists were dealing with different formulas of the same equation, An equation we should never forget, And it stuck in my mind until I die, and I'll tell you what it is.

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The pressure times the volume is equal to the number of moles of gas Steady hit hit temperature. PV = nRT. This is the ideal gas law that applies to all gases As long as the behavior improves. Now, hear the cool part, using this equation, We can show how all of these chemists were dealing with the same relationship, They were just stashing various variants together in different arrangements. All the chemists we mentioned, Charles, Avogadro and Boyle Or rather, to say Townley and Bauer, They arrived at their contribution to the ideal gas law by means of experiments, But what interests me most is that the law can be understood in theory. First, we need to understand what each of these variables mean. In the same way, the atoms and molecules that make up gases collide with things And you put pressure on her. This balloon is inflated because particles are bouncing around inside it And it collides with the balloon from the inside strongly The force of particles colliding with it from the outside exceeds it.

Scientists generally measure pressure According to the international unit system of force newton per square meter, Which is abbreviated to Pascal, but since the units of Pascal are so small, we use kilopascals Or we use atmospheric pressure at sea level Which we call "1 Go" or 1 ATM. By chance, “1 atmosphere” is equal to 101.325 Pa. But the approximation is easier here, so we often say that the "1 atmosphere" is 100,000 Pa Or 100 kPa. Volume is the amount of space in which the particles must be located, So, it stands to reason that the volume decreases when pressure increases Because more particles are in the smaller space And it will hit the walls more. The amount of gas is simply the number of moles in a space. Here I am reducing the amount of gas in this space And the reaction to this is that the volume decreases, as is obvious. The pressure inside the balloon also decreases with it.

R in the ideal gas law is called the "general gas constant", Although we will see in a future episode that it is neither general nor fixed, Whereas, its value is 8.3145 liters kPa / kelvin mol. The temperature for you and me is either cold or hot, But at the atomic level it is kinetic energy This means how fast or slow the particles are moving. Therefore, if the temperature rises, the pressure will rise because the particles are moving more quickly Thus, you will collide with the walls of the space more. So, we now know all the parts of the Ideal Gas Law So let's see it being applied. At Crash Course we love to take safety measures. But this is a bit overkill.

I put some water in this soda can and now I boil it. So the case is now filled with water vapor, not atmospheric gas It is a hot steam and the particles move in a frantic manner. We take it, put it inside that bowl … and it crushes itself. So what happened? Let's see what the gas law will tell us. What changed from these data? Let's start on the right-hand side, R is constant, so it can't change. But the gas temperature has definitely changed, It decreased very quickly when the gas was exposed to ice water. N also decreases as water vapor condenses into water, In this way, it becomes a liquid, not a gaseous. So, the net score on the right is dropping This means that the left-hand net result must have a drop as well. So on the left-hand side, the pressure is really dropping Because the lower temperature makes the particles move more slowly Thus, it reduces collision with the inner walls of the case. The volume is also decreasing. But not for the reason you might think. The reason is that the pressure inside the case gets too low This causes the atmospheric pressure outside the case to crush it inward.

I understand that you may not find this to be as beautiful as I think. But understanding the physical reality of collision of atoms and molecules with each other It is very beautiful to me. It is also nice if we know 3 data about a gas We can find out the fourth by using the gas law. Of course, not all gases behave in the ideal way All gases deviate from the law when the temperature or pressure rises. But we will leave this discussion for a later episode. Time to talk about idiomatic language, STP stands for Standard Conditions of Temperature and Pressure According to the laws of chemistry they are 0 Celsius and 100 thousand Pa Or 100 kPa. One mole of any ideal gas would require 22.4 liters of space at a standard temperature and pressure. This is a fact that can simplify many calculations. Absolute zero is the temperature at which all particles stop moving, It is equal to zero kelvin, or minus 273.15 degrees Celsius. And that's all we have for this episode. Thank you for watching Crash Course in Chemistry. If you are attentive, you may have learned how the work of some brilliant thinkers met To get the perfect gas.

And how none of them was Robert Boyle, And how does the ideal gas equation allow you to know the pressure And volume, temperature and number of moles as long as we already know 3 of those four. And you learned a few chemistry phrases to help you look As if you know what you are talking about. This was an episode of Crash Course Chemistry that I wrote The text was edited by Blake DePastino, The two chemistry consultants are Dr. Haiku Langer and Eddie Gonzalez, It is filmed, edited and directed by Nicholas Jenkins. Script Supervisor is Kathleen Hofmeister and Sound Designer is Michael Arand. And the graphics team is Thought Café..

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