[Calicum]

I know the formula is ln(p1/p2) = ΔHvap/R (1/T2 - 1/T1) but I keep getting the answer wrong.

So far I got:

p1=1
p2=???
T1=373K
T2=385K
ΔHvap=40.65
R=0.0082

[sjb]

I know the formula is ln(p1/p2) = ΔHvap/R (1/T2 - 1/T1) but I keep getting the answer wrong.

So far I got:

p1=1
p2=???
T1=373K
T2=385K
ΔHvap=40.65
R=0.0082

What are your units for R?

[Calicum]

I know the formula is ln(p1/p2) = ΔHvap/R (1/T2 - 1/T1) but I keep getting the answer wrong.

So far I got:

p1=1
p2=???
T1=373K
T2=385K
ΔHvap=40.65
R=0.0082

ΔHvap=40.65 KJ/mol
R=0.0082 KJ/mol K

What are your units for R?

[Calicum]

Nvm I got my answer. 

[JonG]

 R should equal 8.314 J/K mol

[Calicum]

R should equal 8.314 J/K mol

 

Since my ΔHvap is in KJ/mol it would make sense to change R into KJ/mol too. I do not understand what you mean.

[Borek]

R should equal 8.314 J/K mol

 

Since my ΔHvap is in KJ/mol it would make sense to change R into KJ/mol too. I do not understand what you mean.

If you used R equal to 0.082 your units were  L atm K^-1 mol^-1.

[Calicum]

R should equal 8.314 J/K mol

 

Since my ΔHvap is in KJ/mol it would make sense to change R into KJ/mol too. I do not understand what you mean.

If you used R equal to 0.082 your units were  L atm K^-1 mol^-1.

Bah in my first post I wrote 0.0082 and not 0.0083.

My second post corrected this hence the 0.0083KJ/mol which is also equal to 8.314 J/K mol too. Just a little misunderstanding