? G =? H ? T ? S Part A What can be said about an endothermic reaction with a ne

Question

?G=?H?T?S

Part A

What can be said about an endothermic reaction with a negative entropy change?

The reaction is

SubmitHintsMy AnswersGive UpReview Part

Part B

What can be said about an exothermic reaction with a negative entropy change?

The reaction is

The spontaneity of a reaction depends both on the enthalpy change, ?H, and entropy change, ?S. Reactions that release energy produce more stable products, and the universe tends toward disorder. Thus, an exothermic reaction with a positive entropy change will always be spontaneous. Mathematically, this relationship can be represented as

?G=?H?T?S

where ?G is the change in Gibbs free energy and T is the Kelvin temperature. If ?G is negative, then the reaction is spontaneous. If ?G is positive, then the reaction is nonspontaneous as written but spontaneous in the reverse direction.

Part A

What can be said about an endothermic reaction with a negative entropy change?

The reaction is

What can be said about an endothermic reaction with a negative entropy change? spontaneous at all temperatures. spontaneous at high temperatures. spontaneous at low temperatures. spontaneous in the reverse direction at all temperatures. nonspontaneous in either direction at all temperatures.

SubmitHintsMy AnswersGive UpReview Part

Part B

What can be said about an exothermic reaction with a negative entropy change?

The reaction is

What can be said about an exothermic reaction with a negative entropy change? spontaneous at all temperatures. spontaneous at high temperatures. spontaneous at low temperatures. spontaneous in the reverse direction at all temperatures. nonspontaneous in either direction at all temperatures.

Explanation / Answer

case I

?H>0,?S< 0

?G=?H-T?S

for spontaneous, ?G<0

But, using sign convention we can write,

?G=?H+T?S (?S< 0)

So, ?G>0 => spontaneous in reverse direction at all T since T>0 always.

case II

?H<0,?S< 0

?G=?H-T?S

for spontaneous, ?G<0

But, using sign convention we can write,

?G=?H+T?S (?S< 0)

So, ?G<0 only when ?H>T?S => T is small

So, spontaneous at low temperatures.

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.