For Day 59, students completed a micro-electrolysis of cupric chloride to determine whether metals form positively or negatively charged ions.
The electrolysis set-up is simply a piece of aquarium tubing filled with saturated cupric chloride. A 9-volt battery is used as the power source and mechanical pencil lead is used as the electrodes. Students can easily see copper metal forming on the cathode and chlorine gas forming on the anode. The chlorine gas is produced in such small quantities that the smell is not overwhelming but students can still identify it.
After this activity we defined the words “cation” and “anion” and practiced combining ions in the appropriate ratios to balance the charges.