[MPQC]

Okay. So I've got a question of how to determine the boiling point of a closed system (in this quest, a closed flask.)

So the question tells me a few things: The pressure above the liquid is 6.67 kPa. Then, it gives a table of data, of temperatures, and their respective pressure. Though there are only two points that matter:

30° = 4.24 kPa
40° = 7.37 kPa

So, I know that when the vapour pressure is equal to the atmospheric pressure, then that is what the boiling point is. But, I'm not actually sure how to calculate the boiling point - my text gives me no forumula's, and no explained example. So, by this question, I know that the boiling point is somewhere between 30° - 40°, leaning closer towards the 40°, most likely.

At the back of the book, it does show answers. The answer for the question is 38° (37.. It does show some math of how it got that answer, but I'm not really understanding what it's doing. If you want me to type it up, I can, though any help is appreciated.

[savy2020]

http://en.wikipedia.org/wiki/Clausius%E2%80%93Clapeyron_relation#Chemistry_and_chemical_engineering
This might be of help to you.
Clausius-Clayperon equation relates vapour pressures at different temperatures. So using it(and the data) you can find the temp. at which vapor pressure is 6.67kPa.

[MPQC]

Alright, I think that formula will work. . One question though - does it matter which number I substitute into P₁/T₁, and P₂/T₂? Or should I make (for example) T₁ = 30°, and T₂ = 40°, then their respective pressure.)

[savy2020]

I really didn't get what you meant.

[MPQC]

In the question, I have two different temperatures, with their respective pressure. I can plug in the temperatures in two ways..

T₁ = 30°
T₂ = 40°

or

T₁ = 40°
T₂ = 30°

How do I know which number to sub in?

[savy2020]

It doesn't matter which is T₁ and which T₂. But corresponding pressures should be written appropriately
First plug in the given data to get the constant( :delta: H_vap/R).
Again use the equation with only one of the given conditions (say T₁=30^o P1=4.24kPa [you could also use the other]) make P₂ 6.67kPa and find T₂(Your reqd boiling temperature).

Hope it helps

[UG]

Temperature should be in Kelvin I do believe...

[savy2020]

Temperature should be in Kelvin I do believe...

Yes. I'm sorry I overlooked that.