Question

Given the thermochemical equation:

2 Al(s) + 3/2 O2(g) > Al2O3(s) ΔH = -95.7 kJ

find the heat of reaction, ΔH, for the following reaction:

2 Al2O3(s)> 4 Al(s) + 3 O2(g)
Select one:
a. -95.7 kJ
b. +95.7 kJ
c. -47.8 kJ
d. +47.8 kJ
e. +191.4 kJ

Answer 1

You have the reaction as shown. You want the reverse reaction and double that. So take dH that you have, change the sign (because of the reversal) and double it.

Answer 2

would it be a positive or a negative though?

Answer 3

it would be e...

Answer 4

yes.
You reversed the sign because the reaction is reversed. So that makes it positive. Then double that for e.

Answer 5

thank you !!!