[mam2011]

I have a series of questions that build off of each other, and I have answered all of them but the final one incorrectly.
 Question #1: If a volatile liquid is added to a sealed flask, the total pressure inside the flask is a sum of the air pressure and the vapor pressure of the liquid. Consider a flask at 298 K with an air pressure of 741. mmHg to which some n-butanol is added. If the measured pressure after the addition is 746. mmHg, what is the vapor pressure of n-butanol at 298 K?
Answer #1: 5mmHg
Question #2: Now, if the temperature inside the same flask is increased to 328 K the measured pressure will increase to read 863. mmHg. This is because both the air pressure and the vapor pressure of n-butanol will increase. The air pressure at 328 K can be calculated from its value at298 K by using Pi/Ti=Pf/Tf.
(a) What is the value of the air pressure at 328 K (in mmHg)?
I cant seem to figure out what formula to use for this one.  I dont want the answer, I just would like to be explained on HOW to find the answer.
(b) Using that last result and measure pressure at 328 K, what is the vapor pressure of n-butanol at 328 K?
I can't seem to figure out the formula for this. I don't want the answer, I just would like to be explained on HOW to find the answer.

[fledarmus]

They give you the formula to use for a):

The air pressure at 328 K can be calculated from its value at298 K by using Pi/Ti=Pf/Tf.

[mam2011]

That is what I am confused about, I see that formula but im not sure how to use it with the question.  I guess that I am confused on how to set it up.

[fledarmus]

Ahh -

You are given the initial pressure of the air (P_i) at an initial temperature T_i in question 1. You want to know a final pressure of air at a final temperature, 328K. Solve for P_f

[mam2011]

I understand what the question is, I am just not sure if I use the same equation for the second part of the  third question or if there is another one that i am suppose to use.  I am having trouble just setting up or knowing what equation to use. I am not looking for the answer i am just looking for some guidance on how to set it up to answer the question properly.

[fledarmus]

Once you know what the final pressure of the air is (from part a), and knowing what the total final pressure at 328K is (from the question), you simply subtract to find out what the vapor pressure of the n-butanol at your high temperature would be.