T-4 Free Energy Flashcards Preview

Wenger - AP Chemistry > T-4 Free Energy > Flashcards

Flashcards in T-4 Free Energy Deck (19):
1

Define Gibb's Free Energy

Amount of work a spontaneous process can do on its surroundings or the amount of work the surrounds must do to drive a nonspontaneous process

2

How is free energy related to enthalpy and entropy (equation)?

delta G = delta H - T•delta S

3

How is delta Gº related to delta G (equation)?

delta G = delta Gº + RT ln(Q)

4

How is delta Gº related to K (equation)?

delta Gº = -RT ln(K)

5

What is the sign of delta G when a process is spontaneous?

negative

6

At what temperature is a process spontaneous when...

delta H is positive

delta S is positive

At high temperatures -T delta S is larger than delta H

(T= delta H / delta S)

 

7

At what temperature is a process spontaneous when...

delta H is positive

delta S is negative

never spontaneous

 

 

8

At what temperature is a process spontaneous when...

delta H is negative

delta S is negative

Low temperature so that - delta H is greater than + (- of -) T delta S

(T= delta H / delta S is negative)

 

9

At what temperature is a process spontaneous when...

delta H is negative

delta S is positive

At all temperatures

 

10

What is the value for delta G when a system is at equilibrium?

delta G = 0

11

Is the following system shifting to the right, shifting to the left, or at equilibrium?

delta G is negative

Shift right

12

Is the following system shifting to the right, shifting to the left, or at equilibrium?

delta G is zero

at equilibrium

13

Is the following system shifting to the right, shifting to the left, or at equilibrium?

delta G is positive

shifting to the left

14

What is happening to the value of delta G as a reaction shifts to the left

The positive delta G is getting smaller as it heads towards delta G = 0

15

What is happening to the value of delta G as a reaction shifts to the right?

The magnitide of the negative delta G is getting smaller as it heads towards delta G = 0

16

What can you tell me about the value of K for a reaction with a negative delta Gº?

K > 1

delta Gº = -RT ln(K)

17

What can you tell me about the value of K for a reaction with a positive delta Gº?

K

delta Gº = -RT ln(K)

18

What can you tell me about the value of K for a reaction with a delta Gº = 0?

K = 1

delta Gº = -RT ln(K)

19

Delta G for a process at low temperatures is negative.  No product is observed to be forming.  Commnet on the thermodynamic and kinetic favorability of the reaction.

The reaction is thermodynamically favorable (delta G is negative).  Since is does not appear to proceed then it must by kinetically unfavorable (it is very slow).