# Homework Help: Simple thermochemical equation

1. Jan 25, 2007

### SamTsui86

1. The problem statement, all variables and given/known data

2H2(g) + O2(g) --> 2H2O(g) ΔH = −486.6kJ

Which of the following are true statements for the above chemical reaction ?

a) A phase change is involved

b) Two moles of hydrogen gas react with two moles of oxygen gas to
produce two moles of water vapor

c) Energy is absorbed by the system, the reaction species

d) If the reaction takes place at constant volume, q and ΔH must by definition have the same value

e) ΔH for reacting four moles of hydrogen gas with two moles of
of oxygen gas is −483.6 kJ

2. Relevant equations

None

3. The attempt at a solution

I know that A is wrong because they are all gas.
I know that B is wrong because 2 mol of Hydrogen gas react with 1 mol of Oxygen gas
I know that C is wrong because energy was released
I think that D is right because that is no work
I think that E is also right

I've tried DE, E and D
but it's wrong, plz help
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Nov 18, 2016

### Bystander

Check.
Check.
Check.
Check.
"WORNG." Four plus two is twice the energy.

If "D" is "wrong," it could be a matter of limited attempts allowed, or a mistranscription.