Post a New Question Current Questions
Homework Help: Chemistry
Posted by Anonymous on Thursday, November 14, 2013 at 8:45pm.
CONTINUE>>>>>>>>>>>
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 = ?
Ignore the things below.....
First Name:
School Subject:
Answer:
Related Questions
Geometry - Given circle A with circumference 20 pi and the length of arc KD ...
Logic - Can someone please help me solve these problems? I have to use the 17 ...
Economics - I am on the chapter for International Trade in the book. I neew to ...
Sabian - If air resistance offered to the motion of a projectile by the ...
Pre-Cal. - Describe the end behavior of f(x)=2x^4-5x+1: A. x-->�‡, f(x)-->...
Economics - I have the following question in my assignment: The cost of ...
Philosophy (Logic) - I need help constructing a formal proof of validity for the...
math - Solve this : (8x^3 ) - (168x^2) + ( 864x) = 1120 please >>>>&...
Math - help please anyone? i'm having a hard time solvig these problems LOGIC ...
chemistry - Given the equilibrium constant values: N2 + 1/2O2 >>> N2O...
1 answer
NOTE. Note that saying "reverse the sign" is the same as saying "change the sign to the negative" or "take the negative of that value" or any number of similar statements. I don't think I ever said anything about "changing the sign to a negative" but if I did I shouldn't have. In thermochemisty all kinds of equations are written and tabulated with delta H values. If the value is positive the reaction is endothermic and if negative the reaction is exothermic. If we don't like the equation as it is but we want the reverse of that equation, we simply reverse the equation and reverse the sign (a + sign becomes a - sign or a - sign becomes a + sign). Does that change whether it is exothermic or endothermic. You bet it does. If
A==> B is dH = -15 kJ then
B==> A is dH = +15 kJ and what was an exothermic reaction (-15 kJ) becomes an endothermic reaction (+15 kJ). I hope this helps but if not I don't mind trying again. If you pursue this further, please write the question first and comments later. Also, please avoid using all caps--that makes it difficult to read