Chemistry: Henry's law of partial pressure of gas.

[Mr Virtual]

Homework Statement

This is not a textbook question.
Henry's Law states that:
p=kx
where p=pressure of gas
x=mole fraction of gas in solution
k= Henry's constant

and k=p/x
So, we can say that k tells us the pressure of gas per unit x.
Which means k tells us the pressure of the gas when its mole fraction, x is unity.
But what does x=1 mean, since
x=no. of moles of solute/(no. of moles of solute + no. of moles of solvent)

if x=1
then this means: moles(solute)>>moles(solvent)
Am I wrong?

The value of k for helium dissolved in water is 144.97
What does it mean?

Please explain...


Mr V

 

[chaoseverlasting]

When x=1, it means that only that substance is present. I.e., its a pure substance. Hence, when only that gas is present, k is its pressure at that temperature/volume/per mole.

 

[Blueshift5]

it is important to fully understand the concepts and equations we use in our work. Let's break down Henry's Law and address the questions you have raised.

First, Henry's Law states that the amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid. In other words, the higher the partial pressure of a gas, the more of it will dissolve in the liquid.

Now, let's look at the equation p=kx. As you correctly stated, p represents the pressure of the gas and x represents the mole fraction of the gas in solution. The constant k is known as the Henry's constant and it varies depending on the gas and the solvent being used.

Next, you asked about the significance of x=1. This means that the mole fraction of the gas in solution is equal to 1, or 100%. In other words, all of the molecules in the solution are of the gas in question. This is a hypothetical scenario and not usually seen in real life, but it helps us understand the relationship between pressure and mole fraction.

Lastly, you asked about the value of k for helium dissolved in water being 144.97. This means that for every unit of mole fraction of helium in water, the pressure of the gas will be 144.97 units. This value is specific to the system of helium in water and may differ for other gases and solvents.

I hope this explanation helps clarify Henry's Law and its applications. Keep asking questions and seeking understanding in your studies of chemistry!