Because ionized water contains dissolved minerals, such as sodium and calcium, it may not clean as well as deionized water. Your students can put this theory to the test by washing windows or mirrors with each type of water, and then comparing how well each does at leaving a streak-free shine. Ask each student to predict which type of water cleans better and record their hypothesis in a journal or on a lab note worksheet. Provide students with spray bottles of ionized water and deionized water. Ask them to spray each type of water onto separate windows or mirrors and wipe with a paper towel. After the surface dries, have each student record how well it was cleaned.
Deionized water is often added to soap or shampoo to achieve a rich lather. Your students can determine how lather is affected by adding ionized or deionized water to liquid hand soap or liquid dish soap. Provide students with a pair of plastic or latex gloves to protect their hands. Pour a bit of ionized water into one bottle of soap and a bit of deionized water into another bottle of soap. Have students make predictions about which soap will produce more lather. Ask the students to squirt a small amount of soap from one mixture into their hands and rub it together. Repeat with the other bottle of soap. Share conclusions about which kind of water produced more lather.
Since ionized water has minerals, your students may hypothesize that it will benefit plants more than deionized water. Select two identical plants to conduct this experiment. Ask your students to take turns watering the plants regularly; one plant should always get ionized water and the other should always get deionized water. Have your students record their observations over a period of two or three weeks. Discuss any differences in the plants to help determine if one type of water is better than the other.
Water that contains minerals, such as sodium, is denser than pure water. Show your students how density works by dropping objects into ionized water and deionized water to compare what happens. Place a bowl of ionized water and a bowl of deionized water on your work space. Ahead of time, hard-boil two eggs. Discuss with your students how different mineral compositions of water can change whether an object sinks or floats. Carefully lower one egg into the deionized water and have your students observe how it sinks. Ask for predictions about what will happen to the egg in ionized water. Gently lower the other egg into the ionized water to see if it sinks as far into the bowl or if it floats.