Chapter 13 - Fundamentals of Electrochemistry

Question 1

1. A chemical reactions in which there are changes in oxidations numbers.
2. Electrons are ________ from one _______ to another

Answer 1

1. Oxidation-Reducation Reactions

2. transferred, reactant

Question 2

1. Oxidation

2. Reduction

Answer 2

1. Loss of electrons, increase in oxidation number

2. Gain of electrons, decrease in oxidation number

Question 3

the charge of the atom would have if the electrons were assigned according to set rules a. Based on the assumption that all atoms in compounds are ______

Answer 3

Oxidiation

a. ions

Question 4

1. Reducing agents

2. Oxidizing agents

Answer 4

1. (Oxidizing): The reactant in the redox give up its electrons
2. (Reducing): The reactant in the redox that accepts electrons

Question 5

1. Any process in which oxygen is added to another substance is an
2. Halogens and oxygen

Answer 5

1. oxidation

2. oxidizing agents

Question 6

When Redox occurs in aqueous solutions we can balance using _____

Answer 6

half reactions: breaking the reaciton into two half reaction
- one for oxidization and one for reduction

Question 7

Voltaic (Galvanic Cells):

1. Flow of electrical charge
   - ___ flow through the wire
   - ____ flow through the solution

Answer 7

1. electrical current
   - electrons
   - ions

Question 8

Device used to carry out the generation of electricity through redox reactions.

Answer 8

electrochemcial cell

Question 9

Electrochemical cell that produces electrical current from a spontaneous chemical reaction.

Answer 9

Voltaic (Galvanic) Cell

Question 10

Consumes electrical current to drive a nonspontaneous reactions.

Answer 10

Electrolytic cell

Question 11

Volatic (Galvanic) Cells:
Two separate chambers are the _____

Two pieces of metal are the _____
- Electrical conductors within a cell that serve as sites for ______.

Two solutions containing a _____ of the corresponding ____.

Two half-cells are connected by a ___ running from the ____ to monitor ____.
- A ______e between the two solutions.

Answer 11

half-cells

electrodes
- chemical reactions

dissolved salt, metal

wire, electrodes, electric current
- salt bridge

Question 12

Anode:

Cathode:

Answer 12

oxidation take place, the source electron in current flow

reduction take place, receiving electrons sent from anode

Question 13

what are the two things a salt bridge is needed?

For the cell to operate the two electrolytes (the solutions) must be in ___.
Electrons that remain when ions emerge from
the metal in the left cell ___ through it and into
the right electrode solution making new
____ from cations.

Answer 13

prevents the solution from rapidly mixing and allows ions to diffuse through

flow, atoms

Question 14

electrical current is proportional to….

cell voltage is proportional to

Answer 14

rate of reaction

free energy change for the reaction

Question 15

1. measured in in coulombs (C)
2. The quantity of charge flowing each second through a circuit
   - measured in
3. The difference electrical potential (E) between two point is the ___ needed when moving an ___ ____ from one point to another

Measure of difference in potential energy per unit charge

Large potential difference between two electrodes means …..

Answer 15

1. electric charge (q)
2. current
   - Ampes (A)
3. work, electric charge

Potential difference

strong tendency for electric flow

Question 16

Can measure the amount of electric charge that passes through the electrodes.

Answer 16

potentiometer

Question 17

Each electrode in each half-cell has it’s own individual potential.

• Typically called the_____
• Each reaction has one.

the difference between the two standard electrode potentials.

Answer 17

Standard Electrode Potental (Eº)
- reduction potential

Overall Standard Cell Potential (Eºcell)

Question 18

The half-cell that is normally have a potential of zero

Answer 18

Standard hydrogen electrode

Question 19

calculate cell potential under non-standard conditions

Answer 19

Nernst Equation

Question 20

The reaction is not spontaneous so a power source is required.

• Energy is stored in an ______
• That energy can be released when the cell is allowed to run in a ___ mode.
• ___ reaction

Answer 20

electrolytic cell

• electrochemical cell
• galvanic
• reverse

Question 21

A battery is the common word for a ____l.

Answer 21

galvanic cell

Question 22

Reference electrond:

1. The half-cell electrode that has a potential of zero.
   Consists of a Pt surface in contact with an acidic solution in which AH+ = 1.
   Arbitrarily assign a potential of 0 at 25oC.
2. Standard reduction potential when saturated in KCl = +0.241 V
   At 25oC.
   Assuming activities are 1.
3. KCl, the E = 0.197.
   At 25oC.
   Assuming activities are 1.
   A double-junction electrode:
   Minimizes contact between analyte solution and KCl from the electrode.
   Often times however, the porous plugs become clogged

Answer 22

1. SHE
2. SCE
3. Ag/AgCl

Question 23

Potential Errors:

1. Whenever dissimilar electrolyte solutions are in contact, a voltage difference called the ____ develops at their interface.
   Occurs at the porous plug.
2. You have to have good standards!
3. If one of the solutions starts to precipitate, there will be a slow ____
4. When [Na+] is high the apparent pH may be lower than the true.
5. The measured pH is higher than the actual.
6. Have to allow enough time for the electrode to equilibrate.
7. A dry electrode will not measure accurately.
   8: Should be calibrated at the same temp of the solutions.

Answer 23

1. Junction potential
2. Standards
3. Drift
4. Akaline error
5. acid error
6. equilibrium
7. hydration
8. temperature