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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Amahia11 on February 05, 2010, 06:25:06 AM

Title: Thermochemistry- Bond Energy
Post by: Amahia11 on February 05, 2010, 06:25:06 AM

To find the P-Cl Bond Energy in a PCl3(l) bond...

well heres what i did..

P(s) + 1.5Cl2(g) -----> Pcl3(l)

to atomise P(s) into P(g) 315 kj

to atomise 1.5 Cl2(g) to 3Cl 3(122) kj

we atomise Pcl3 to a gas now or what? help much appreciated! thanks!

Title: Re: Thermochemistry- Bond Energy
Post by: cliverlong on February 05, 2010, 10:33:45 AM

Have you been given data for the standard enthalpy of formation of PCl₃ ?

http://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formation

Are you clear what goes in  and what comes out when one is given  :delta: H_f for any compound?

I always find a Hess Law diagram really helps showing all the various enthalpy changes, those for which the question gives me data, and those the question asks me to calculate.

Clive