Water Module: Session 7 Galvanic Cells and Ion Concentrations

How can a digital multimeter be used to measure cell voltage?

Do the classroom multimeter exercise (p S7:1)

1. Why do the batteries not have the same voltage?

2. What is the effect of interchanging the leads?

3 Which electrode is the source of electrons for the flow of current?

Make your own galvanic cell. (p S7:3)

1. Which electrode should be labeled as positive and which negative?

2. Which way would the electrons flow if the electrodes were connected?

3. Write out the cell reaction that occurs when the cell discharges.

4. How would you construct a battery to generate 12 V with the cell you are using?

Determine the emf series for three metals (p S7:4 – 5)

1. Which metal is the best reducing agent?

2. Which metal ion is the best oxidizing agent?

How does the potential of the cell depend on ion concentration?

Experiment with different solution concentrations

1. How is the potential affected by concentration?

Ion-selective electrodes

Indicator electrode Reference electrode

Logarithmic relationship allows use to very low concentrations

pH electrode good from 0.1 to 10^-12 M