Posted by Kate on .
HELP!!
I cannot find the value of ÄH, for the following reactions.
A + 2B > C + 3D , ÄH = 154 kJ
1/2C + 3/2D > 1/2A + B, ÄH= ?
I have tried the answers 302 and 154 and neither were correct.
Have any suggestions?? Thank You!

Chemistry 
bobpursley,
Isnt the second reaction the first reaction backwards, or 1/2 of it backwards, so deltaH=154/2 kJ

Chemistry 
Kate,
Yes, the 2nd reaction is the 1st reaction reversed.
The book says when you have a reaction that is reversed, take the opposite sign of the ÄH... which should be 154 by that definition. I'm not sure if I am suppose to divide 154 by 2?? 
Chemistry 
bobpursley,
yes, you are supposed to divide. It is 1/2 of the first reaction backwards.