Need help with thermal chem... please show work so i can learn... my prof sucks!?

Question

Carbon tetrachloride can be formed by reacting chlorine with methane:

CH4 + 2 Cl2 à CCl4 + 2 H2

Given that the heat of formation of methane is –75 kJ/mol and the heat of formation of carbon tetrachloride is –135 kJ/mol, determine the heat of reaction.

Given the following equations and Ho values given below, determine the heat of reaction at 298 K for the reaction:
2 N2(g) + 5 O2(g) =2 N2O5(g)
2 H2(g) + O2(g) = 2 H2O(l) Ho/kJ = -571.6
N2O5(g) + H2O(l) = 2 HNO3(l) Ho/kJ = -73.7
N2(g) + 3 O2(g) + H2(g) 2 HNO3(l) Ho/kJ = -348.2
JUST FOR INFO Ho = delta h degrees

The specific heat capacity of aluminum is 0.900 J/oC g. How much energy (kJ) is needed to raise the temperature of a 8.50 x 102 g block of aluminum from 22.8oC to 94.6oC?

Answer 1

C + 2H2 ===> CH4 -75kJ/mol Therefore:

CH4 ===> C + 2H2 +75kJ/mol

C + 2Cl2 ===> CCl4 -135kJ/mol Add the two equations:

CH4 + 2Cl2 ===> CCl4 -60kJ/mol (The C's cancelled out)

You do the second problem in the same way. Arrange the equations backwards or forwards as needed, reversing the sign of deltaH as needed, ending up with 2N2 and 5O2 on the left side and 2N2O5 on the right, with everything else cancelling out. Then add up the deltaH's, (-)'s and (+)'s.

Last problem: 94.6C - 22.8C = 71.8deg difference

8.50x10^2gAl x 71.8deg x 0.900J/deg-g = 5.49 x 10^4J = 54.9kJ