Question

Study the following two reactions. Select all that apply.

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?
a The enthalpy of CO2 is greater than the reactants.
b E2 - E1 is negative.
c Graphite and diamond have equal enthalpy.
d Diamond must have lower internal energy.

Answer 1

Its B and D
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Answer 2

Option B only

Step-by-step explanation:

First to all, we have the same reaction in both equations, the difference between the two of them, is the fact one is Carbon in the form of graphite, and the other is carbon in the form of diamond.

Now, both reactions release energy in the form of heat, and it appears in the side of the products, this means that both reactions are exothermic (An exothermic reaction is when energy is released as product in the equation).

If energy is released in the reaction, (Which is enthalpy), this value is negative. As this value is negative, means that the internal energy of CO2 has to be lower than the energy of the reactants, so, option A can be discarted.

If we do E2 - E1:

-94.5 - (-94.05) = -0.45 kcal

Therefore, option B is correct.

As we can see the energy released in both equations, is different for both, so, graphite and diamond do not have equal enthalpy.

Finally, as the combustion of diamond releases more energy that the combustion of graphite (94.5 > 94.05), means that diamond has a higher internal energy than graphite. and Option D can be discarted.