Mg(s) + ½O2(g) → MgO(s) + 146 kcal/mole H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal/mole What type of reaction is represented by the previous two examples?

Question

Mg(s) + ½O2(g) → MgO(s) + 146 kcal/mole  H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal/mole  What type of reaction is represented by the previous two examples?

thomaster · Answer

Lol how did you manage to get half a molecule of oxygen?  xD

thomaster · Answer

Anyway a reaction with oxygen is called a combustion reaction

anonymous · Answer

@thomaster Could you take a look at my question?

anonymous · Answer

exothermic or endothermic?

thomaster · Answer

Exothermic = energy released (ΔH will be negative)
Endothermic = energy needed (ΔH will be positive)

So which one will it be?

anonymous · Answer

im asking if the reaction of the representation above is exothermic or endothermic.

anonymous · Answer

nevermind. i got it now. lol hah

thomaster · Answer

Yes and i am trying to explain to you what exothermic and endothermic means :P
With a combustion reaction, heat is released so it's probably exothermic
And the ΔH is negative

anonymous · Answer

thanks. how about this one:

C(graphite) + O2(g) → CO2(g) + 94.05 kcal

C(diamond) + O2(g) → CO2(g) + 94.50 kcal

What could you infer from the information given above?

-The enthalpy of CO2is greater than the reactants.
-E2- E1is negative.
-Graphite and diamond have equal enthalpy.
-Diamond must have lower internal energy.