Vapor Pressure of Water

[ThetaSigma87]

Im doing a lab, trying to find the molar volume of a gas. I'm stuck on a step that is asking for the vapor pressure of water.

This is all the data I have collected for two separate trials.

-Mass of Magnesium: T1:45g T2:46g

-Volume of Gas Mixture: T1:48mL T2:50mL

-Atmospheric Pressure: T1:750.81torr T2:749.554torr

-Water Bath Temperature: T1:20C T2:18C

Vapor Pressure of Water: T1:? T2:?

I know you can't give me the answer, I just need to know what to do to find the vapor pressure. I am completely lost on this and I feel like it is incredibly simple.

[steph33]

T1 temperature at which the vapor pressure is known

T2 temperature at which the vapor pressure is to be found

use formula ln(P1/P2) = (ΔH_vap/R)((1/T2) - (1/T1))

good luck