ctrXuyen Ha prelab 1. Objective : measuring the voltage changes in ½ cells when concentrations are altered in reaction

hypothese:according to the Nernst equation, changes in concentration should not change

2. Materials : beakers multimeter bare copper wires copper ions in solution (copper nitrate) graduated cylinder salt bridge test tube

3. Method/steps
1. Obtain 100mL 1m copper nitrate and serial dilute to obtain concentrations of 0.1M, 0.01M, and 0.001M
2. Obtain approximately 100mL of each dilution
3. Split the 1M copper nitrate into two small test tubes and place the copper wire into each test tube.
4. Place the salt bridge ends into each of the test tubes
5. Measure voltage with a voltmeter by contacting each lead to each wire. After the first measurement turn off multimeter and record again after turning voltmeter back on.
6. Repeat steps 3-5 with each serial dilution.
7. Record voltage readings on the given tables on part 4 4. Data/graphs

concentrations | first reading (volts) | second | average | 1M | 7.4mV | 7.5mV | 7.45mV | 0.01M | 68.8mV | 63.8mV | 66.3mV | 0.001M | 82mV | 80.2mV | 81.1mV | 0.0001M | 93.3mV | 92.5mV | 92.9mV | 0.00001M | 100.5mV | 102mV | 101.25mV |

5. Discussion : write the half-cell reactions as well as the total overall equation for this reaction.

at the anode: Cu(s) -> Cu+2 + 2e- at the cathode : Cu+2 + 2e- -> Cu(s)

combined: Cu+2 + 2e- + Cu(s) -> Cu(s) + Cu+2 + 2e-

Theoretical vs experimental values

series 1 shows the experimental values collected while series 2 are the values calculated using the known concentrations of copper ion and plugging those values into the Nernst equation.

6. Conclusion: what conclusions can be drawn from the different voltage readings of differing concentrations? The greater the difference in concentrations and