Wednesday

August 20, 2014

August 20, 2014

Posted by **Anonymous** on Thursday, November 14, 2013 at 8:45pm.

The enthalpy changes for two different hydrogenation reactions of C2H2 are:

C2H2+H2---->C2H4 Delta H 1 (there is a degree sign....standard enthalpy of formation??)

*****WAIT A SECOND, IF I USE THE HEAT OF FORMATION VALUES TO CALCULATE THEN WOULD THAT GIVE THE ENTHALPY OF RXN???...which is not relevant to this question,right???

*****But if you change the sign to a neg then how do you know that it is positive originally???I AM VERY VERY PERPLEXED,DR.BOB!!!!!!!!!

I DO UNDERSTAND THAT YOU HAVE TO SWITCH ACCORDING TO HESS'S Law, but I DO NOT UNDERSTAND HOW YOU KNOW THE SIGNS......!!!!!!!!!!!!!!!!!!!!

Why is it pos to neg ??????????

I thought it is the other way around!!!!

BUT DO YOU UNDERSTAND WHAT I DO NOT GET??? IF NOT, I WILL TRY TO CLARIFY IT.

THANK YOU FOR YOUR PATIENCE!!!!

C2H2+2H2---->C2H6 Delta H 2 (there is a degree symbol)

Which expression represents the enthalpy change for the reaction below?

C2H4+H2---->C2H6 Delta H = ?

- Chemistry -
**DrBob222**, Thursday, November 14, 2013 at 11:42pmSee your post above.

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