Chapter 20

Question 1

Anode half reactions go from?

Answer 1

solid to aq

Question 2

Cathode half reactions go from?

Answer 2

aq to solid

Question 3

How to Balance Redox Reactions in Basic Solution?

Answer 3

1. Assign oxidation states
2. Write two half reactions
3. Balance all atoms except for H and O
4. Balance O atoms by adding H2O and balance H atoms by adding H+ (aq)
   4b. For every H+ atom added, add an OH- atom to BOTH sides of the reaction.
   4c. Combine the H+ and OH- atoms occurring on both sides of the equation to form H2O
5. Balance the charge of both half reactions by adding electrons.
6. Equalize the electrons in both half reactions.
7. Add the two equations to make an overall reaction.

Question 4

How to Balance Redox Reactions in Acidic Solution?

Answer 4

1. Assign oxidation states
2. Write two half reactions
3. Balance all atoms except for H and O
4. Balance O atoms by adding H2O and balance H atoms by adding H+ (aq)
5. Balance the charge of both half reactions by adding electrons.
6. Equalize the electrons in both half reactions.
7. Add the two equations to make an overall reaction.

Question 5

How to label a voltaic (or galvanic) cell:

Answer 5

Electrons move from the cathode to the anode.

At the anode, the element is being oxidized (losing electrons). Labeled with a negative (-) sign.

At the cathode, the element is being reduced (gaining electrons). Labeled with a positive (+) sign.

The salt bridge provides more protons to the cathode and more electrons to the anode.

Question 6

1 Ampere (or amp) =

Answer 6

1 C/s

Question 7

1 Volt (V) =

Answer 7

1 J/ C

Question 8

E cell is…
(definition)

Answer 8

cell potential or cell emf

Question 9

E cell Naught is…
(definition)

Answer 9

The standard cell potential or standard emf

Question 10

A double vertical line in electrochemical cell notation means…

Answer 10

the separation between the two-half reactions

Question 11

The equation for E cell naught for cathode and anode is…

Answer 11

E0= E0 final- E0 initial
E0= E0cathode- E0anode

E0= E0cath- E0ano

Question 12

The reaction is nonspontaneous if the E0 is?

Answer 12

Negative

Question 13

The reaction is spontaneous if the E0 is?

Answer 13

Positive

Question 14

The reaction is spontaneous if the reduction half reaction is paired with?

Answer 14

the REVERSE of any equation listed below it. on the table

Ex. F2(g) +2e- —> 2F- (aq) [at the top of the list] is spontaneous with reverse of Br2(l)+ 2e- —> 2Br- (aq) [12 spots below fluorine]

Question 15

For a spontaneous redox reaction, ΔG0 is _____, E0cell is _______, and K is _____ _____ 1.

Answer 15

ΔG0 is negative
E0cell is positive
K is greater than 1

Question 16

For a nonspontaneous redox reaction, ΔG0 is _____, E0cell is _______, and K is _____ _____ 1.

Answer 16

ΔG0 is positive
E0cell is negative
K is less than 1

Question 17

Equation between ΔG and E0:

Answer 17

ΔG0= -nFE0cell

ΔG0 is the standard change in free energy

n-moles of electrons in the BALANCED equation

F is Faraday’s constant

Question 18

What is the value of Faraday’s constant, F?

Answer 18

96485 C/ mol e-

Question 19

Equation between E0 cell and K:

Answer 19

E0 cell= (0.0257/n) lnK

Question 20

Equation of E0cell involving R, T ,n ,F, and K?

Answer 20

E0cell= (RT/nF)lnK

R- 8.314 (J/molK)
F- 96485 (C/mol e-)

Question 21

What is the Nernst Equation at standard conditions?

Answer 21

E cell= E0 cell- (0.0257 V/ n)* lnK

Question 22

What is the Nernst equation at nonstandard conditions?

Answer 22

E cell= E0cell- (0.0257V/n)(ln Q)

Question 23

If half reactions are identical (where one is in the fwd direction and one is in the reverse), the STANDARD CELL POTENTIAL is…

Answer 23

E0cell= 0

Question 24

In voltaic cells, the cathode is ____ charged and the anode is ____ charged.

Answer 24

positively (+)

negatively (-)