Lab 9

Question 1

Oxidation- Reduction (Redox) Reactions

Answer 1

Flow of electrons between the compounds occurs spontaneously

Question 2

Galvanic (Voltaic) Cell

Answer 2

Closed circuit through which electrons flow spontaneously between the individual half reaction cells

Question 3

Half Cell

Answer 3

Each half reaction isolated into a separate cell

Each will contain a strip of solid metal and solution of metal ions

Question 4

Electrodes

Answer 4

The two solid metals that are connected to the external circuit

Question 5

Anode

Answer 5

Electrode at which oxidation occurs

Negative polarity

Question 6

Cathode

Answer 6

Electrode at which reduction occurs

Positive polarity

Question 7

Salt Bridge

Answer 7

Circuit between the electrodes is completed with this addition between the half cells which is filled with an inert electrolyte that allows the ions to flow between the two cells so that electrical neutrality is maintained in the cells and the reaction can continue to occur

Question 8

Cell Potential (Ecell)
Electromotive Force (emf)

Answer 8

Electrons at anode of the voltaic cell have a higher potential energy than electrons at cathode of a voltaic cell, therefore the electrons will spontaneously flow from the anode to the cathode; this potential energy is this
Measured in units of volts (J/C) and depends on specific reactions at cathode and anode as well as concentration of reactants and products and temperature
Always positive if spontaneous reaction

Question 9

Standard Cell Potential (Ecell)

Answer 9

Cell potential of the electrochemical cell under standard temperature (25C) and standard concentrations (1M)

Question 10

Standard Cell Potential (Ecell)

Answer 10

Cell potential of the electrochemical cell under standard temperature (25C) and standard concentrations (1M)
For an electrochemical cell depend son the reactions that occur in each half cell

Question 11

Standard Reduction Potential (Ered)

Answer 11

Used in standard cell potential calculation
Can’t be measured directly from a single half cell because no electron transfer resulting in a current occurs with only one half cell
Measured in reference to a certain half-reaction that is assigned a standard reduction potential of zero

Question 12

Standard Hydrogen Electrode (SHE)

Answer 12

Most commonly used reference electrode

2H+ (aq, 1M) + 2e- –> H2 (g, 1atm) Ered = 0V

Question 13

Standard Reduction Potential (Ered)

Answer 13

Used in standard cell potential calculation
Can’t be measured directly from a single half cell because no electron transfer resulting in a current occurs with only one half cell
Measured in reference to a certain half-reaction that is assigned a standard reduction potential of zero
More positive

Question 14

Standard Hydrogen Electrode (SHE)

Answer 14

Most commonly used reference electrode
2H+ (aq, 1M) + 2e- –> H2 (g, 1atm) Ered = 0V
Spontaneous reaction if standard reduction potential is positive and coupled with SHE

Question 15

Standard Oxidation Potential (Eoxi)

Answer 15

Reverse reaction for half cell
Equal to -Ered
More negative

Question 16

Nernst Equation

Answer 16

Ecell = Ecell - 0.0592/n logQ

Used to determine the cell potential of an electrochemical cell under non-standard conditions

Question 17

Electrolytic Cell

Answer 17

Type of cell in which a non-spontaneous chemical reaction is driven by electrical energy

Question 18

Purpose

Answer 18

To understand the relationship between reduction potential and reaction spontaneity. To measure relative reduction potentials of metals.