THE VOLTAIC (GALVANIC) ELECTROCHEMICAL CELL. 4/26 - PowerPoint PPT Presentation

About This Presentation
Title:

THE VOLTAIC (GALVANIC) ELECTROCHEMICAL CELL. 4/26

Description:

the voltaic (galvanic) electrochemical cell. 4/26 objectives: using standard reduction potentials to predict cell standard voltage (e0) and spontaneity. – PowerPoint PPT presentation

Number of Views:92
Avg rating:3.0/5.0
Slides: 10
Provided by: STFr8
Category:

less

Transcript and Presenter's Notes

Title: THE VOLTAIC (GALVANIC) ELECTROCHEMICAL CELL. 4/26


1
THE VOLTAIC (GALVANIC) ELECTROCHEMICAL CELL. 4/26
  • OBJECTIVES
  • USING STANDARD REDUCTION POTENTIALS TO PREDICT
    CELL STANDARD VOLTAGE (E0) AND SPONTANEITY.
  • CALCULATING WORK POTENTIAL OF A VOLTAIC CELL.
  • USING THE NERNST EQUATION TO FIND NONSTANDARD
    VOLTAGE.
  • CALCULATING ?G RT Ln K
  • CALCULATING MOLES FROM APPLIED CURRENT.
  • CALCULATING CURRENT FROM MOLES REACTED.
  • CONSTRUCTING THE CELL COMPONENTS FROM THEORY AND
    LOGIC.

2
  • OBJECTIVE
  • USING STANDARD REDUCTION POTENTIALS TO PREDICT
    CELL STANDARD VOLTAGE (E0) AND SPONTANEITY.
  • YOU NEED VOLTAGES FROM REDUCTION POTENTIAL TABLES
    FOR EACH HALF REACTION.
  • REVERSE THE REDUCTION THAT HAS THE LOWEST
    VOLTAGE, THAT IS YOUR OXIDATION ( THE HIGHER
    VOLTAGE IS THE HIGHER REDUCTION POTENTIAL)
  • BALANCE HALF REACTIONS AS USUAL, HOWEVER, NEVER
    MULTIPLY VOLTAGES.
  • CALCULATE EO USING
  • EOCELL EOREDUCTION EOOXIDATION

3
  • OBJECTIVE
  • USING STANDARD REDUCTION POTENTIAL, PREDICT CELL
    STANDARD VOLTAGE (E0) AND SPONTANEITY FOR
  • Zn(S)/Zn2Cu2/Cu(S)
  • EOCELL EOREDUCTION EOOXIDATION
  • GIVEN FROM REDUCTION POTENTIAL TABLES
  • Cu2 2e- ??Cu0(S) EO 0.34 V
  • Zn2 2e- ??Zn0(S) EO -0.76 V

4
  • OBJECTIVE
  • USING STANDARD REDUCTION POTENTIAL, PREDICT CELL
    STANDARD VOLTAGE (E0) AND SPONTANEITY FOR
  • Zn(S)/Zn2Cu2/Cu(S)
  • GIVEN FROM REDUCTION POTENTIAL TABLES
  • Cu2 2e- ??Cu0(S) EO 0.34 V
  • Zn2 2e- ??Zn0(S) EO -0.76 V
  • EOCELL EOREDUCTION EOOXIDATION
  • E0CELL (0.34V) (-0.76V) 1.10V

THE CELL POTENTIAL OF THIS CELL IS POSITIVE,
WHICH MEANS THE CELL IS SPONTANEOUS AND ?G IS
NEGATIVE..
5
  • OBJECTIVE
  • USING STANDARD REDUCTION POTENTIAL, PREDICT CELL
    STANDARD VOLTAGE (E0) AND SPONTANEITY FOR
  • Zn(S)/Zn2Cu2/Cu(S)
  • GIVEN FROM REDUCTION POTENTIAL TABLES
  • Cu2 2e- ??Cu0(S) EO 0.34 V
  • Zn0(S) ?? Zn2 2e- EO 0.76 V
  • Zn0(S) Cu2 ? Cu0(s) Zn2 EO 1.10 V

THE REDUCTION POTENTIAL OF THE ZINC ION IS LOWER
THAN COPPER THE ZINC HALF REACTION MUST BE
REVERSED AND THE SIGN OF ITS VOLTAGE RECIPROCATED.
6
  • OBJECTIVE
  • CALCULATING WORK and ?G OF THE CELL
  • Zn(S)/Zn2Cu2/Cu(S)
  • GIVEN FROM REDUCTION POTENTIAL TABLES
  • Cu2 2e- ??Cu0(S) EO 0.34 V
  • Zn0(S) ?? Zn2 2e- EO 0.76 V
  • Zn0(S) Cu2 ? Cu0(s) Zn2 EO 1.10 V
  • ?G 2.303 RT Log K
  • OR
  • wMAX nFE0 and (?G - wMAX)
  • wMAX (2mol e-) (96,500 C/mol e-)(1.10 V)
  • wMAX 212,000 J 212 kJ
  • ?G -212 kJ

7
  • OBJECTIVE
  • CALCULATING NON-STANDARD E WITH THE NERNST
    EQUATION FOR
  • Zn(S)/Zn2Cu2/Cu(S)
  • Zn0(S) Cu2 ? Cu0(s) Zn2 EO 1.10 V

NON-STANDARD IS MOLARITIES OTHER THAN 1.0 AND
TEMPERARES OTHER THAN 25OC
ENONSTANDARD EO 0.0592 V (LOG Q)
n
(
)
ENONSTANDARD EO 0.0592 V LOG Zn2
n
Cu2
ENONSTANDARD EO 0.0592 V LOG Zn2
n
Cu2
(
)
NOTE ? values of the voltages and n, you can
use the Nernst equation to solve for Q or
molarities of ions.
8
ENONSTANDARD 0.0296 V (1.30) 1.06 V
  • IF THE MOLARITIES ARE 1.O MOLAR
  • (OR P 1 atm) FOR ALL SPECIES, Q 1 AND E0 E.
  • 2. E RARLEY EO DUE TO INEFFICIENCY, BACK
    VOLTAGE AND RESISTANCE IN THE CELL

9
  • OBJECTIVE CALCULATING ?G RT Ln K OR (?G
    2.303 RT Log K)
  • FOR THE CELL Zn(S)/Zn2Cu2 /Cu(S)
  • ?G 2.303 RT Log K -nFEo
  • Log Kc nEo
  • 0.0592 V
Write a Comment
User Comments (0)
About PowerShow.com