Question #7be8c

1 Answer
Ernest Z.
Sep 2, 2017

The pressure would be 1029 Torr.

Explanation:

Henry’s law says that the concentration c of a gas in a solvent is directly proportional to the partial pressure p of the gas above the solvent.

The mathematical expression for Henry’s law is

color(blue)(bar(ul(|color(white)(a/a)c = k_text(H)pcolor(white)(a/a)|)))" "

where k_text(H) is is a proportionality constant called the Henry's Law constant.

If we have the same solute in the same solvent at two different pressures p_1 and p_2, we can write

c_1 = k_text(H)p_1

and

c_2= k_text(H)p_2

Dividing the two equations, we get

c_1/c_2 = (color(red)(cancel(color(black)(k_text(H))))p_1)/(color(red)(cancel(color(black)(k_text(H))))p_2) = p_1/p_2

∴ p_2 = p_1 × c_2/c_1

The volumes of solvent are the same, so we can use the masses of the solute instead of concentrations.

∴ p_2 = "772.0 Torr" × (0.4960 color(red)(cancel(color(black)("g"))))/(0.3720 color(red)(cancel(color(black)("g")))) = "1029 Torr"

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