3. 10/07/2016 ++++++++ -- Solution containing copper ions Impure copper Cu 2+ Pure copper

4. Impure copper is used as the anode of an electrolysis cell. The battery pulls electrons off the copper atoms in the anode. By losing electrons these atoms become copper ions and so the anode slowly ‘dissolves’ away. Impurities just sink to the bottom as ‘anode mud’.

5. Opposite charges attract. Positive copper ions (Cu 2+ ) move towards the negative cathode. At the cathode these ions gain electrons and turn into copper atoms. So, during electrolysis a copper cathode gets thicker.

6. Copper is purified using electrolysis. Plan an experiment to investigate how the mass of the cathode (negative electrode) changes over time. What is the independent variable? What is the dependent variable? What are you control variables?

7. Recording your Results Design a table to collect your results in This is usually the thing you change These are usually the things you have measured NEVER FORGET YOUR UNITS!!! (e.g. s, m, cm, N) Use a PENCIL and RULER

8. Apparatus A 3.3g

9. Draw a graph of your results What is the shape of your graph? Why is it this shape?