Intro to Henry's Law - Video Tutorials & Practice Problems
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According to Henry's Law, at a constant temperature the amount of a gas dissolved in a solvent is directly proportional to its partial pressure when it is in equilibrium with its liquid phase.
Intro to Henry's Law
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concept
Intro to Henry's Law Concept 1
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When it comes to Henry's law, it's important to understand that the solubility of a dissolved gas is directly proportional to the partial pressure of that gas over the liquid. So when we talk about Henry's law, we have to take into account 2 different relationships. Those are the pressure solubility relationship and the temperature solubility relationship. Now you're going to say, as the pressure increases above gases that are over liquid, then the solubility of a gas increases. So all you have to think about is I have this closed container and I can apply outward pressure on it, pushing down on this piston. That puts pressure on the gases that are above the liquid. And what happens here is that added pressure forces the gases to go down into the water, making them become dissolved, and thereby increase their solubility. Now we're gonna say here changes in pressure have no effect on solids or liquids. So this is only in terms of increasing the solubility of gases if we increase the pressure on them. Now with temperature and solubility, that relationship we're gonna say as the temperature increases, then the solubility of a gas decreases. So think about it like this. You have a pot of water that you're boiling on the stove. Right? The lid is closed. And if you give it enough time, what starts to happen? Steam starts to come out of the water. Well, that's gas escaping the water. It's no longer dissolved in the solvent, and therefore, its solubility is decreasing. Because Remember solubility is being able to dissolve a solute within a solvent. Now we're gonna say here, temperature and solubility does not only affect gases, but it can also affect solids. We're gonna say as the temperature increases, the solubility of a solid actually increases. So if you think you have like a hard, like, substance like a rock or something in here, and you boil it in there, what's gonna happen? Eventually, the rock is gonna break apart, break down. It's gonna become dissolved within the solvent. So just remember, increasing the temperature on solids increases their solubility.
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example
Intro to Henry's Law Example 1
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In general, as the temperature increases, the solubility of a gas in a given liquid so remember, we increase the temperature on a solution, the gases are gonna start escaping that solution and thereby decrease their solubility. And the solubility of most solids in a given liquid will increase. Okay. So think about hard substance like a rock, throw it into, boiling that of water. Over time, that rock can be broken down by those increased temperatures. So here we're gonna have decreases and then increases. So here, option b would be the correct answer.
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Problem
Problem
Which of the following is true for the solubility of KBr (s) and CH3(CH2)3CH3 (g) in water?
A
Decreasing the temperature will decrease the solubility of CH3(CH2)3CH3.
B
Increasing the pressure will decrease the solubility of KBr.
C
Both KBr and CH3(CH2)3CH3 are completely soluble in water.