Lemon juice is a versatile substance with applications for everything from hair care to baking to household cleaning. Lemon juice can lighten hair, sour milk and help heal a sore throat. It's a common household staple and is a component of many products, whether for its chemical properties or simply its fresh scent.

One of the primary chemical properties of lemon juice is its low pH. With a highly acidic pH level of 2, lemon juice lies just below stomach acid on the pH scale. Lemon juice's high acidity means that it has a high concentration of hydrogen ions. Like other acidic substances, lemon juice is sour and can corrode metals. Its corrosive properties make it a useful ingredient in cleaning products, because it softens the minerals in hard water, allowing the cleaning agents to work more effectively.

Lemon juice contains high levels of vitamin C. On average, lemons contain about twice as much vitamin C as oranges. Physicians first discovered this characteristic of lemons in the seventeenth century, when they found that consuming lemon juice every day could prevent outbreaks of scurvy. However, the high levels of vitamin C in lemon juice are lost if the juice is left exposed to the air for a long period of time.

Research suggests that lemon juice also has certain antimicrobial properties. Studies indicate that lemon juice can stop the growth of aspergillus mold, and lemon juice has been used to disinfect drinking water and deactivate the rabies virus. This property of lemon juice seems to be tied to its citric acid content, which can break down the cell membranes of bacteria.