Water is the most important chemical to us since we evolved out of water, are made of about 60% water, and need water to live. Water has the chemical formula of H2O, however water can break down into the ions of H+ and OH-. The amount of H+ in water is measured in units of pH that can range for 0 to 14. Pure water has a pH of 7. Animals can live in water between the pH of 4 to 10, outside that range, most living things die. Red cabbage juice changes color at different pHs and can be used to measure pH of water samples. This project will calibrate the cabbage juice color scheme against standards of know pH, and then use cabbage juice to test to quality of water under different conditions. With this experiment, the students will learn qualitative analytical chemistry.