Kaplan General Chemistry: Chapter 12 Electrochemistry

Question 1

galvanic cells utilize ___ reaction

Answer 1

spontaneous

Question 2

electrolytic cells utilize ___ reactions

Answer 2

nonspontaneous

Question 3

concentration cells utilize ___ reactions

Answer 3

spontaneous

Question 4

oxidation occurs at the ___

reduction occurs at the ____

Answer 4

oxidation, anode

reduction, cathode

Question 5

if EMF is +, the G is:

if EMF is -, then G is:

Answer 5

EmF is the voltage/ electrical potential difference of the cell.
if EMF is +, the G is: SPONTANEOUS
if EMF is -, then G is: NONSPONTANEOUS

Recall: G=-nFE

Question 6

movement of electrons is ALWAYS ___ to ___

Answer 6

anode to cathode

Question 7

in galvanic cells, the chemical that wants to be reduced (+E) is at the ____

Answer 7

cathode. it IS being reduced. results in a >0 cell potential.

Question 8

why do electrolytic cells need an input of energy?

Answer 8

becaues they house nonspontaneous reactions. This oxidation-reduction reaction is driving by an ecternal voltage souce. The amount of chemical change induced in an electrolytic cell is directly proportional to the number of moles of electrons that are exchanged during the oxidation reduction reaction.

Question 9

How can voltage be calculated using the Nersnt Equation?

Answer 9

Ecell = E"cell - (RT/nF)(lnQ)
Ecell= E''cell - (0.0592/n)logQ

Question 10

in a galvanic cell, the anode = ____ and the cathode ___

Answer 10

in galvanic: anode = negative, cathode = positive.

Question 11

in an electrolytic cell, the node = ____ and the cathode = _____

Answer 11

anode = positive elctrode because it is attached to the POSITIVE pole of the external voltage source, and attracts ANIONs

cathode = negative electrode because it is attached to the negative pole of the external voltage source and attracts CATIONS from the solution.

although there is a charge difference, oxidation still takes place at the anode and reduction still takes place at the cathode in BOTH types of cells. regardless of charge designation, the cathode ALWAYS attracts cations and the anode ALWAYS attracts anions.

Question 12

Unit of Newtons

Answer 12

J/m = Kgm/s^2

Recall: Work = Fd therefore F=W/d units: J/m

Question 13

unit breakdown of a Joule

Answer 13

J = Nm = Kgm^2/s^2

Question 14

How to calculate EMF od cell

Answer 14

E’cell = E’reduced,cathode - E’redanode

or Ecell = E’reducedcathode + E’oxidizedanode

Question 15

how to measure the work done by an electrochemical apparatus

Answer 15

W=qV

Question 16

useful G equations

Answer 16

deltaG’= -RTlnKeq
deltaG’= -nFE’cell = -RTlnK
deltaG=G’ + RTlnQ

Ecell = E’cell - (RT/nF)lnQ