Baking soda is basic, with a pH value of 9. Drop 1 teaspoon (4.9 mL) of it into a glass of water, and then stir briskly with a spoon or whisk. Keep stirring until all of the crumbs of baking soda have dissolved. Then, measure the water’s pH again using a litmus strip. If you started with neutral water (pH 7), the water’s pH should have increased up to about 8. Mix the 2 liquids together using a spoon. Then dip a strip of litmus paper into the water. Wait a few seconds, and note how the pH level of the water has changed. Since lemon juice is acidic, with a pH value of 2, the pH level of a neutral glass of water should have lowered to a 6 or 5. Many common liquids and dissolvable substances found around the home will alter the pH level of water. Dissolve or mix a small amount of one substance at a time into a glass of clean water, and then test with a litmus strip. If you’re performing a science experiment, make a chart on which you can record the pH values of water with different substances added, each to a separate glass of water. Try adding:  Coke. Red wine. Milk. Liquid soap or shampoo.
Add 1 teaspoon (4.9 mL) of baking soda to an 8 oz (230 g) glass of water. Add 1 teaspoon (4.9 mL) of lemon juice to a glass of water. Experiment with various other basic and acidic materials.