Question

2H2 + O2 → 2H2O
AH = +285.5 kJ mol-1
What will be the enthalpy change in the above reaction?
A) 205.5 kJ/mol
C) -205.5 kJ/mol
B) Zero kJ/mol
D) 1 kJ/mol​

Answer 1

Explanation:

The enthalpy change for the following reaction is -483.6 kJ:

2H2 (g) + O2 (g) → 2H2O (g)

Therefore, the enthalpy change for the following reaction is __________ kJ:

4H2 (g) + 2O2 (g) → 4H2O (g)

a. 483.6

b. -967.2

c. 967.2

d. 2.34 x 10^5

e. -483.6

I think it is b, since it seems that since the equation was just multiplied by two, the enthalpy would also be multiplied by 2. (2 * -483.6) = -967.2

I don't know if this is right though. I am consistently getting thrown off by how to determine whether answers should have positive or negative H's.

Answer 2

Answer:

C

Explanation:

-285.5-2(40.6)=-205.5 kJ /mol