CHM
2045C Module Seven Sample Exam
Module
Seven Part G: Hess Law of Constant Heat Summation 10 points
Using the following equations:
S (s)
+ 3/2 O2
(g) → SO3 (g) ∆
Ho = -395.2 kJ
2 SO2 (g) +
O2 (g) → 2 SO3 (g) ∆ Ho = -198.2 kJ
calculate the ∆ Ho for the reaction:
S
(s) +
O2 (g) → SO2 (g)
Given the following equations:
B2O3 (s) + 3H2O (g) →
B2 H6 (g) + 3 O2 (g) ∆ Ho = +2035 kJ
H2O (l) → H2O (g) ∆ Ho
= +44 kJ
2 B (s)
+ 3 H2 (g) →
B2 H6 (g) ∆ Ho
= +36 kJ
H2 (g)
+ 1/2 O2 (g) → H2O (l) ∆ Ho = -286 kJ
Calculate
the ∆ Ho for the reaction:
2 B (s)
+ 3/2 O2 (g) → B2 O3 (s)
Answer: -1273 kJ