Question

What drives spontaneous reactions?

Select one:
a. decreasing enthalpy and decreasing entropy
b. decreasing enthalpy and increasing entropy
c. increasing enthalpy and decreasing entropy
d. increasing enthalpy and increasing entropy

Answer 1

Answer:

option B

Explanation:

A spontaneous reaction drive favorable when enthalpy is decreasing and the entropy is increasing on the system. If that happens the reaction occurs spontaneously

Answer 2

Answer:

b. decreasing enthalpy and increasing entropy

Explanation:

∆H stands for enthalpy change and ∆S stands for entropy change

Spontaneity depends on the enthalpy and entropy changes of the reaction

∆G = ∆H - T∆S

When ∆H is negative and ∆S is positive  

∆G will be negative

For a spontaneous reaction ∆G is negative

If ∆G = 0 then the reaction will be at equilibrium  

If ∆G is positive the reaction is non spontaneous.

Decreasing enthalpy (negative) and increasing entropy (positive) will give a negative number for $\Delta G$