ELECTROCHEMISTRY

Kristin ShepardBrooke Petersen

ELECTROCHEMICAL CELLS- TERMS

Electrode- Any cell that is used to conduct electricity; Where the reaction actually takes place- Solid Part

Anode- Solid where the oxidizing happens Cathode- Solid where the reduction occurs Current- The flow of electrons- Electricity Salt Bridge- Concentrated salt solution with

ions that will not react with solutions

STANDARD CELL POTENTIAL

Standard Cell Potential is known as E° There are four simple steps

1. Even the electrons2. Flip the most negative equation3. Add the equations4. Add the E°

CALCULATING ∆G°

To calculate this, we use the following equation when all substances are at standard conditions ∆G°= -nFE°

CALCULATING K

After finding the ∆G°, we can now find K using: ∆G°= -RTlnK

HOW MANY MOLS OF PT MAY BE DEPOSITED ON THE CATHODE WHEN 0.80 F OF ELECTRICITY IS PASSED THROUGH A 1.0 M SOLUTION OF PT4+ ?

(A)1.0 mol(B)0.60 mol(C)0.20 mol(D)0.80 mol(E)0.40 mol

It takes 4 mol of electrons (4F) to change the platinum ions to platinum metal. The calculation would be: (0.80)(1 mol Pt/4 F)= 0.20 mol Pt.

WHAT HAPPENS TO THE CELL VOLTAGE WHEN THE COPPER ELECTRODE IS MADE SMALLER?

(A)There is no change in the voltage.(B)The voltage becomes zero.(C)The voltage increases.(D)The voltage decreases, but stays positive.(E)The voltage becomes negative.

The size of the electrode is not important.

WHAT HAPPENS TO THE CELL VOLTAGE AFTER THE CELL HAS OPERATED FOR 10 MINUTES?

(A) There is no change in the voltage.(B) The voltage becomes zero.(C) The voltage increases.(D) The voltage decreases, but stays positive.(E) The voltage becomes negative.

As the cell operates, the copper ion concentration would decrease and the zinc ion concentration would increase. Both of these changes would make the logarithm term in the Nernst equation more negative. This would decrease the voltage.