Lesson 11 Electrochemistry

Question 1

Redox Reactions

Answer 1

Chemical reaction that involves a transfer of electrons between two species.

Question 2

Electrochemistry (Definition)

Answer 2

The study of electricity and how it relates to chemical reactions.

Question 3

Electricity (Definition)

Answer 3

The flow of electrons.

Question 4

Oxidation Numbers (States)

Answer 4

Shows the total number of electrons which have been removed from an element (positive oxidation state/number) or added to an element (negative oxidation state/number) to get to its present state.

Question 5

Oxidation Numbers Rules (Group 1A & 2A metals)

Answer 5

1A = +1
2A = +2

Question 6

Oxidation Numbers Rules (Element by itself)

Answer 6

Zero

Cl2 = 0
Ba = 0
Mg = 0

Question 7

Oxidation Numbers Rules (Halogens)

Answer 7

Usually -1, positive with Oxygen

Question 8

Oxidation Numbers Rules (H)

Answer 8

+1 w/ nonmetals
-1 w/ metals

Question 9

Oxidation Numbers Rules (Oxygen)

Answer 9

Usually -2
-1 w/ peroxides (H2O2)

Question 10

Oxidation Numbers Rules (F)

Answer 10

Always -1

Question 11

OIL RIG

Answer 11

Oxidation is LOSS (of electrons)
Reduction is GAIN (of electrons)

Question 12

Oxidizing Agent

Answer 12

Reactant that is being reduced (gaining electrons).
-species that causes the oxidation.

Question 13

Reducing Agent

Answer 13

Reactant that is being oxidized (loses electrons).
-species that causes reduction.

Question 14

Oxidized (Does Oxidation Number go up or down)

Answer 14

Up (loss of electrons)

Question 15

Reduced (Does Oxidation Number go up or down)

Answer 15

Down (gain of electrons)

Question 16

Steps for Balancing Redox Reactions in Acidic Solutions

Answer 16

1. Determine the Oxidation Numbers
2. Figure out what’s been oxidized and
   reduced.
3. Write the half equations.
4. Balance atoms other than the O and H
5. Add H2O to balance O, and H+ to balance
   H.
6. Add electrons to balance charges
7. Multiply half reactions to make the number
   of electrons equal on both sides.
8. Add half reactions together and cancel out
   stuff that appears on both sides.
9. Do a final check to make sure everything
   balances.

Question 17

Steps for Balancing Redox Reactions in Basic Solutions

Answer 17

1. Determine the Oxidation Numbers
2. Figure out what’s been oxidized and
   reduced.
3. Write the half equations.
4. Balance atoms other than the O and H
5. Add H2O to balance O, and H+ to balance
   H.
6. Add electrons to balance charges
7. Multiply half reactions to make the number
   of electrons equal on both sides.
8. Add half reactions together and cancel out
   stuff that appears on both sides.
9. For each H+ add one OH to both sides.
10. Combine H+ and OH- to make H2O.
11. Subtract H2O from both sides if possible.
12. Do a final check to make sure everything
    balances.

Question 18

Galvanic (Voltaic) Cell

Answer 18

Electrochemical cells in which spontaneous redox reactions produce electrical energy.

Question 19

Anode

Answer 19

Cell in which oxidation takes place. (Loses mass)

Question 20

Cathode

Answer 20

Cell in which reduction takes place. (Gains mass)

Question 21

Salt Bridge

Answer 21

Keeps the solutions nuetral.

Question 22

Salt Bridge (Where do anions flow)

Answer 22

Anions flow into the anode (positive ions break apart from solid metal when they lose electrons to make the solution more positive).

Question 23

Salt Bridge (Where do cations flow)

Answer 23

Cathode (positive ions in solution gain electrons (reduction) to form neutral metals and combine with cathode to leave a more negative solution).

Question 24

Electrode that loses mass

Answer 24

Anode

Oxidation occurs at the anode.

Question 25

Electrode that gains mass

Answer 25

Cathode

Reduction occurs at the cathode.

Question 26

Electrochemical Cell (Galvanic)

Answer 26

Device used to generate electrical energy from a spontaneous oxidation-reduction reaction.

Question 27

Red Cat and An Ox

Answer 27

Reduction is cathode.
Anode is Oxidation.

Question 28

Cell Notation

Answer 28

Shorthand notation of galvanic (voltaic) (spontaneous) cells.

Question 29

Cell Notation Rules

Answer 29

Double vertical line (||) used to separate anode and cathode. (Anode on the right).

Single vertical line (|) used to separate different states of matter on the same side.

Commas (,) used to separate like states of matter on the same side.

(Don’t show ions that don’t change charges)

Question 31

Cell Potential from E (Standard Conditions) Equation

Answer 31

Ecell = E(reduction/cathode) - E(oxidation/anode)

Question 32

Negative or Smaller Ecell Value is always the (Anode or Cathode)?

Answer 32

anode

Question 33

How to identify and Oxidation-Reduction Reaction?

Answer 33

The oxidation numbers must have changed.