Ion Migration

We separate the ions in copper dichromate gel using electrolysis. We see the positive blue copper ions move to the negative electrode and the negative yellow chromate ions move to the positive electrode. Chemistry - Reactions - Learning Points. Ions have a positive or a negative charge. Positive copper ions are attracted to a negative carbon electrode; negative chromate ions are attracted to a positive carbon electrode. Some ions have distinctive colours; these are usually the ions of the transition metals. A Twig Experiment Film. Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.