Chemistry help please!!! Practice exam please show how to calculate?

Given the following data calculate the change in H for the reaction CaC2(s) + 2 H2O(l) > Ca(OH)2(aq) + C2H2(g)

data: Ca(s) + 2C > CaC2 change in H = -62.8 kJ
Ca(s) + 1/2 O2(g) > CaO(s) change in H = - 635.5 kJ
CaO(s) + H2O(l) > Ca(oh)2 (aq) change in H = -653.1 kJ
C2H2(g) + 5/2 O2(g) > 2CO2(g) + H2O(l) change in H = -1300kJ
C(graphite) + O2(g) > CO2(g) change in H = -393.51 kJ

?2011-03-21T09:38:59Z

Favorite Answer

Leave eqn 1, 2 & 3 as they are.
Reverse eqn 4
Multiply eqn5 by 2
In all cases include the change in the value of dH.
Then cancel out the cancelables. The answer is -712.82kJ = 713kJ