# chemistry question #1

## Recommended Posts

Naphthalene, a substance present in some mothballs, has an enthalpy of vaporization of 49.4kl/mol. If the vapor pressure of naphthalene is .300mmhg at 298K, what is the temp at which the vapor pressure is 7.6x10^2mmhg?

##### Share on other sites

• 1 month later...

Revise phase equilibria and Raoults law.

$P=P^ym$

P is the vapour pressure of the solution, $P^y$=vapour pressure of the pure solvent $m$=mole fraction of solvent in the solution.

Use $pV=nRT$ to find kelvin.

##### Share on other sites

what you need here is nor raoult's law or the ideal gas law, what you need is the clausius clapeyron equation. Look it up in your textbook.

##### Share on other sites

Ideal gas equation should help! I agree with DeanK2

##### Share on other sites

honestly, the ideal gas law might or might not help, but the clausius clapeyron equation is designed for exactly this situation:

$\ln(\frac{P_{2}}{P_{1}}) = \frac{\Delta H_{vap}}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})$

apologies for the non-greek spelling for delta, but latex wouldnt accept the symbol. Note that you're given the deltaHvap and T1 and P1 and P2. just solve for T2

Edited by Cap'n Refsmmat
fixed the greek - you just needed to put a space after it and a \ before it. - ecoli (also fixed the ln - Cap'n)
##### Share on other sites

For future reference,

$\Delta$ is obtained by $\Delta$

Cheers. EDIT: Never mind. Looks like you figured it out all on your own. ##### Share on other sites

EDIT: Never mind. Looks like you figured it out all on your own. that was actually my doing... "last edited by ecoli..."

##### Share on other sites

how'd you do the ln?

##### Share on other sites

You use \ln. You can click on the latex image to display the code, just so you know.

## Create an account

Register a new account