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.
أضف ملعقة صغيرة (٥ مل) من صودا الخبز إلى كوب (٢٥٠ مل) من الماء. أضِف ملعقة صغيرة (٥ مل) من عصير الليمون إلى كوب (٢٥٠ مل) من الماء. جرّب إضافة موادًا قاعدية وحمضية مختلفة.