Exercise 17.16 Predict the spontaneity of a reaction (and the temperature depend

Question

Exercise 17.16

Predict the spontaneity of a reaction (and the temperature dependence of the spontaneity) for each possible combination of signs for H andS (for the system).

Part A

H negative, S positive

SubmitMy AnswersGive Up

Part B

H positive, S negative

SubmitMy AnswersGive Up

Incorrect; Try Again; 5 attempts remaining

Part C

H negative, S negative

SubmitMy AnswersGive Up

Part D

H positive, S positive

SubmitMy AnswersGive Up

Provide FeedbackContinue

Chemistry 106 Summer 2016

Help

Close

Homework Set #6

Exercise 17.16

ResourcesConstantsPeriodic Table

« previous 9 of 22 next »

Exercise 17.16

Predict the spontaneity of a reaction (and the temperature dependence of the spontaneity) for each possible combination of signs for H andS (for the system).

Part A

H negative, S positive

negative,  positive The reaction will be nonspontaneous at all temperatures. The reaction will be nonspontaneous at low temperature, but spontaneous at high temperature. The reaction will be spontaneous at all temperatures. The reaction will be spontaneous at low temperature, but nonspontaneous at high temperature.

SubmitMy AnswersGive Up

Part B

H positive, S negative

positive,  negative The reaction will be spontaneous at low temperature, but nonspontaneous at high temperature. The reaction will be spontaneous at all temperatures. The reaction will be nonspontaneous at low temperature, but spontaneous at high temperature. The reaction will be nonspontaneous at all temperatures.

SubmitMy AnswersGive Up

Incorrect; Try Again; 5 attempts remaining

Part C

H negative, S negative

negative,  negative The reaction will be nonspontaneous at all temperatures. The reaction will be spontaneous at all temperatures. The reaction will be nonspontaneous at low temperature, but spontaneous at high temperature. The reaction will be spontaneous at low temperature, but nonspontaneous at high temperature.

SubmitMy AnswersGive Up

Part D

H positive, S positive

positive,  positive The reaction will be spontaneous at all temperatures. The reaction will be spontaneous at low temperature, but nonspontaneous at high temperature. The reaction will be nonspontaneous at low temperature, but spontaneous at high temperature. The reaction will be nonspontaneous at all temperatures.

SubmitMy AnswersGive Up

Provide FeedbackContinue

Explanation / Answer

Answer – We are given the signs for the H and S , so from that we need to determine the spontaneity of a reaction for each possible combination.

We know spontaneous process is the process which completed its own without external force. The process which release the energy and move to lower energy and become more stable. We know the temperature change also affect the spontaneity, since there is change the Gibbs free energy of the reaction.

G = H - TS

Part A) H negative ,S positive –

We know when the process releases the energy then it is spontaneous process and when energy release the sign of the H is negative and change in entropy is postive, so when H negative and S positive then process is always spontaneous.

So answer for this one is - The reaction will be spontaneous at all temperatures.

Part B) H positive, S negative –

We know when the process release the energy then it is spontaneous process and when energy release the sign of the H is negative, but here H is positive. So when H positive and S negative then process is never spontaneous. If reaction gets reverse, then H is negative and spontaneous process.

So answer for this one is - The reaction will be nonspontaneous at all temperatures.

Part C) H negative, S negative –

We know when the process releases the energy then it is spontaneous process and when energy release the sign of the H is negative and change in entropy is positive, but in this one we are given S negative so we need low temperature for the negative Gibbs energy. So when H negative and S negative then process is spontaneous at low temperature.

So answer for this one is - The reaction will be spontaneous at low temperature, but nonspontaneous at high temperature

Part D) H positive, S positive –

We know when the process releases the energy then it is spontaneous process and when energy release the sign of the H is negative, but here H is positive. So when H positive and S positive then process is spontaneous at high temperature, since when high temperature then there is Gibb’s free energy comes negative and process gets spontaneous.

So answer for this one is - The reaction will be nonspontaneous at low temperature, but spontaneous at high temperature.

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

---

---

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