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

Question

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 pressure, q = −483.6 kJ


e) ΔH for reacting one mole of hydrogen gas with a half mole of
of oxygen gas is −241.8 kJ

Answer 1

a) False. The compounds are gases throughout.
b) False. One mole of oxygen gas.
c) False. The (-) means that energy is "given off" (exothermic)
d) True
e) True (Just divide them in half.)

Answer 2

The answer is d.and e

This is an exothermic reaction, meaning that heat is released. Exotherms have a negative sign for the delta H and q, because heat is leaving the system.

If you look at the other answers, a is wrong because everything is a gas
b is wrong because the belanced equation does not match the wording in b.

e is correct because -241.8 is half of -483.6

Answer 3

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