It appears from the answer that I'm the one that answered but your last question really is too confusing to me to make sense of it.
Let me point out that it is never a good idea to break a question up into two or more parts and make two or more post of it. What you are experiencing is a good example of that.
For this question my answer stands. If you reverse dH1 (and the equation that goes with it) to make it -dH1 and add the two equations, you get -dH1 + dH2 = the expression you want and that would be rearranged to make it dH2-dH1. That makes the answer to this question C. I have no idea how this relates to some other question you may have posted recently. If you wish you might try posting ALL of the question and ALL of the possible answers AND YOUR WORK and let us take a look at it. As to exo or endothermicity, I can't even guess without knowing values for dH1 and dH2.
I know I posted this question before, but can you clarify it??
MY QUESTION IS AFTER YOU SWITCHED THE DELTA H1 THE CHANGE IN THE ENTHALPY IS NEGATIVE.... BUT THAT DOES NOT MAKE SENSE BECAUSE THE CHANGE IN ENTHALPY OF THE ORIGINAL DELTA H1 IS NEGATIVE(ACCORDING TO THE CALCULATION OF THE ENTHALPY OF FORMATION YOU TOLD ME TO DO EARLIER...) AND SO AFTER SWITCHING IT WOULDN'T IT BE POSITIVE?????AND PLUS THIS IS PUTING THINGS TOGETHER WHICH IS EXOTHERMIC WHICH HAS A NEGATIVE H......PLEASE EXPLAIN..........
The enthalpy changes for two different hydrogenation reactions of C2H2 are:
C2H2+H2---->C2H4 Delta H 1
C2H2+2H2---->C2H6 Delta H 2
Which expression represents the enthalpy change for the reaction below?
C2H4+H2---->C2H6 Delta H = ?
A. Delta H 1 + Delta H 2
B. Delta H 1 - Delta H 2
C. Delta H 2 - Delta H 1
D. -Delta H 1- Delta H 2
You said....
Reverse H1 (make - dH) and add to H2.
1 answer