NaOH, commonly called lye, is used very often in cleaning products like soap and oven cleaner. With a pH of 14, NaOH is a very strong base and burns tissues on contact. In contrast, HCl, or hydrochloric acid, is an extremely acidic substance and rates a pH of 0.
The pH scale measures how acidic or basic a substance is. Anything with a pH higher than 7 is a base, whereas substances with a pH lower than 7 are acids. Most substances range from 0 to 14 on the pH scale.Learn more about Acids & Bases