1. Use data below to calculate energy change when 0.80 grams of methane is completely burned in oxygen: CH4 (g) + 2O2 (g) -> CO2 (g) + 2H2O,?H=- 890KJ/mol
A. -44.5 KJ
B. 712 KJ
C. -712 KJ
D. 890 KJ
E. -890 KJ
Answer: A


2. The standard enthalpy of combustion of methanol (CH3OH) is -709 kj/mol. What is the approx. mass of methanol that must be burned completely in oxygen in order to produce 70.9 KJ of energy?
A. 3.2 g
B. 16 g
C. 32 g
D. 70.9 g
E. 709 g
Answer: A

I don't understand these at all..please help? Thanks soooo much in advance!!!!