Chapter 18 - Electrochemistry

Question 1

an electrochemical cell that PRODUCES electrical current from a SPONTANEOUS chemical reaction

Answer 1

voltic (or galvanic) cell

Question 2

an electrochemical cell that CONSUMES electrical current to drive a NONSPONTANEOUS chemical reaction

Answer 2

electrolytic cell

Question 3

a measure of the difference in potential energy (usually in joules) per unit of charge (coulombs)

• units in volts (V) = 1 J/ C
• aka, electromotive force (emf)

Answer 3

potential difference

Question 4

cell potential

Answer 4

a measure of the overall tendency of the redox reaction to occur spontaneously - the lower the cell potential, the lower the tendency to occur

Question 5

if the cell potential is negative, the forward reaction is (spontaneous/nonspontaneous)

Answer 5

non spontaneous

Question 6

anode

Answer 6

the electrode where oxidation occurs

the more negatively charged electrode in a voltaic cell

Question 7

cathode

Answer 7

the electrode where reduction occurs

the more positively charged electrode in a voltaic cell

Question 8

what is the purpose of the salt bridge?

Answer 8

the negative ions within the salt bridge flow to neutralize the accumulation of positive charge at the anode, and the positive ions flow to neutralize the negative charge at the cathode. The salt bridge completes the circuit.

Question 9

in a voltaic cell, electrons flow…

Answer 9

from the more negatively charged electrode to the more positively charged electrode

Question 10

standard cell potential can be calculated by…

Answer 10

the difference in voltage between the cathode (final state) and the anode (initial state)

Question 11

the electrode in any half-cell with a greater tendency to undergo reduction is positively charged relative to the SHE and therefore has a (positive/negative) electrode potential

Answer 11

positive

Question 12

the electrode in any half-cell with a lesser tendency to undergo reduction is negatively charged relative to the SHE and therefore has a (positive/negative) electrode potential

Answer 12

negative

Question 13

Ecell is (positive/negative) for spontaneous reactions

Answer 13

positive

Question 14

Ecell is (positive/negative) for non spontaneous reactions

Answer 14

negative

Question 15

for a spontaneous redox reaction…

Answer 15

• change in G is negative
• Ecell is positive
• and K is greater than 1

Question 16

for a non spontaneous redox reaction…

Answer 16

• change in G is positive
• Ecell is negative
• K is less than 1

Question 17

• the anode is the source of electrons and has a negative charge (anode - )
• the cathode draws electrons and has a positive charge (cathode + )

in (voltic/electrolytic) cells

Answer 17

voltic

Question 18

• electrons are drawn away from the anode, which must be connected to the positive terminal of the external power source (anode + )
• electrons are forced to the cathode which must be connected to the negative terminal of the power source (cathode - )

in (voltic/electrolytic) cells

Answer 18

electrolytic