Select the correct answer,
What is the AG for the following reaction at 25°C?
N204(8) 2N02(9)
Given:
N20409): AG= 98.28 kJ/mol
NO2(9): AG= 51.8 kJ/mol
OA 5.32 kJ/mol
OB. 10.64 kJ/mol
OC -5.32 kj/mol
OD. -10.64 kJ/mol

Choice A: .

Explanation:

The Gibbs Energy change in a reaction can be found from the Gibbs Energy of formation :

.

In this case,

.

Note that since there are two molecules on the product side of this reaction, the for

One way to interpret this equation is to think about what means.

Refer to the diagram attached. The value of a substance is the energy it takes to form one mole of it from its elements under the standard conditions.

In this case, the two are like vectors that points from the elements to the two substances. However, the problem is asking for , which is the dashed arrow that points from to . To find that value, invert (the arrow on the left-hand side) and add that to (the arrow on the right-hand side.) The resultant value would be the dashed arrow, which stands for . In other words, .