Place a few drops of soluble ink on a piece of toilet paper. Dip the paper into a container of water. Water migration will separate the ions or spread out the different colors that created the final ink color. Black ink and markers used for transparencies are good for use in this student experiment.
Fill a glass with water. Place an ice cube in the glass. Dangle the end of a string onto the ice cube. Sprinkle salt on the ice cube and leave it for a few minutes. Lift the string and watch the ice cube come out of the water glass.
Place baking soda in water. It will separate into two ions, sodium and bicarbonate. Pour vinegar into water. It will partially separate into two ions, hydrogen and acetate. Mix vinegar, baking soda and water together and it will form a new compound, carbonic acid. Carbonic acid decomposes into carbon dioxide gas and water. This composition of ions can be used to fuel a homemade rocket, expand a balloon or demonstrate the eruption of a model volcano.
Ionic compounds such as salt conduct electricity when placed in water. Electrolysis separates elements by passing electricity through them. A cathode is negatively charged and an anode is positively charged. Cations will move toward a cathode and anions will move toward an anode. Connect copper wire to the positive and negative terminals of a 9-volt battery. Connect the end of each wire to copper strips and immerse each copper strip into a glass beaker containing a mixture of salt and distilled water. The water will split into hydrogen and chlorine gas as the electricity from the battery passes through the electrodes.