text: Lemon juice is about 5 % to 6 % ( approximately 0.3 M ) citric acid , which gives lemons a sour taste , and a pH of 2-3 . This makes lemon juice an inexpensive , readily available acid for use in educational science experiments .
simplified: Lemon juice is about 5 % citric acid , and has a pH of 2 to 3 .