Electrochemistry

Question 1

What are redox reactions?

Answer 1

involve a transfer of electrons

Question 2

How can you tell what will dissolve in HCl using standard electrode potentials?

Answer 2

If it’s lower on the chart than 2H+ to H2 then it will dissolve in HCl

Stronger reducing agents/weaker oxidizing agents will dissolve

Question 3

How can you find the Q required to make a reaction that is non spontaneous under standard conditions spontaneous?

Answer 3

Find E0cell

Use Nernst equation and plug 0 in for Ecell

Solve for Q

Question 4

What half reaction occurs at the anode?

Answer 4

oxidation (an ox)

Question 5

What half reaction occurs at the cathode?

Answer 5

reduction (red cat)

Question 6

What direction do electrons flow in a galvanic cell?

Answer 6

anode to cathode

Question 7

What is a double vertical line represent in a galvanic line notation? What about single line?

Answer 7

salt bridge

phase seperation

Question 8

How can you tell if a redox reaction is spontaneous?

Answer 8

by calculating E0cell using standard half reactions, if its positive its spontaneous, if negative its non spontaneous

Question 9

What electrode is used to measure the other standard reaction potentials?

Answer 9

standard hydrogen electrode

E0cell=0V

Question 10

What is the formula for E0cell?

Answer 10

E0cathode-E0anode

Question 11

What are the steps to balancing a redox reaction in acidic solution?

Answer 11

1. seperate into half reactions
2. balance elements other than O and H
3. add water to balance oxygen atoms
4. add hydrogen to balance H+
5. multiply the half equations to balance e-
6. add them together and cancel out

Question 12

What are the steps to balancing a redox reaction in basic solution?

Answer 12

1. separate into half reactions
2. balance elements other than O and H
3. add water to balance oxygen
4. add H+ to balance hydrogen
5. multiply to balance electrons
6. add together and cancel electrons
7. add oh- to balance H+, combine to make water
8. cancel common terms

Question 13

What is the reaction for H+ dissolving solids?

Answer 13

2H+(aq) + solid(s) –> H2(g) + solid(aq)

Question 14

What is the other way metals can be dissolved?

Answer 14

HNO3

NO3- + 4H+ + 3e- –> NO + 2H2O (anything below this will be dissolved in HNO3)

Question 15

For a spontaneous reaction what will the value of Gibb’s, Ecell, and K be?

Answer 15

G<0, Ecell>0, K>1

Question 16

For a nonspontaneous reaction what will the value of Gibb’s, Ecell, and K be?

Answer 16

G>0, Ecell<0, K<1

Question 17

What formula connects deltaG0 and E0cell?

Answer 17

deltaG0=-nFE0cell

F is a constant (96485), n is # of electrons transferred

Question 18

What formula relates E0cell to K?

Answer 18

E0cell=(0.0257/n)lnK

n is # of electrons transferred

Question 19

What formula relates deltaG0 to K?

Answer 19

deltaG0=-RTlnK

Question 20

How can we find Ecell at non standard conditions?

Answer 20

Ecell=E0cell-0.0257/nlnQ

Question 21

If you make a voltaic cell by connecting identical half cells under standard conditions what will happen?

Answer 21

no reaction will happen

Question 22

How can you find Ksp using measuring concentrations of cell potentials?

Answer 22

using nernst equation determine what concentrations are in Q, solve for unknown concentration, find Ksp formula, plug in concentration and solve for Ksp