In this lab, you will determine the pH of chemical solutions using red cabbage juice as a natural pH indicator. Solutions can be acidic, basic, or neutral, depending on the concentration of hydrogen ions (H+/H3O+) and hydroxide ions (OH–). Acids contain more H+/H3O+ ions, while bases have more OH– ions. Neutral solutions have equal amounts of both, with a pH of 7. A pH below 7 is acidic, while a pH above 7 is basic.

Red cabbage juice contains anthocyanin, a pigment that changes color based on pH. In acidic solutions, it turns red or pink, while in basic solutions, it becomes green or yellow. Neutral solutions keep it purple. The color changes because anthocyanin responds to the concentration of hydrogen ions, making it a clear and effective pH indicator.