# chemistry

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What pressure would have to be applied to steam at 325°C to condense the steam to liquid water (ÄH vap = 40.7 kJ/mol)?

Responses

Dr bob please! Chemistry - GK, Friday, November 28, 2008 at 11:47pm
Use the Clausius-Clapeyron Equation to calculate the vapor pressure at 325°C. That is the pressure that must be applied to condense the steam at 325°C.
Ln(P2/P1) = (∆H/R)[(T2-T1)/T2T1]
P1 = 1 atm
∆H = 40700J
R = 8.3145 J/°K.mol
T2 = (325+273) = 598°K
T1 = (100+273) = 373°K
P2 = (unknown)

[NOTE: The pressure needed is quite high]

Dr bob please! Chemistry - Rachelle, Sunday, November 30, 2008 at 10:06pm
i solved for lnx=4,852,725

whats next? and i relaly cant put it into the calc. it says (overflow)

• chemistry -

You must be punching the calculator wrong somewhere. By the way that was GK that gave you that answer in such nice detail. I worked the problem and end up with
ln P2 = 4.93777 and when I click on ex I get an answer. Your digits are about the same but the decimal point is way different.
If you want to type in your set up and the follow through I will check it for you step by step.

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