Learn the pH of Common Chemicals

The pH of lemon juice is around 2, making this fruit highly acidic
The pH of lemon juice is around 2, making this fruit highly acidic. ANDREW MCCLENAGHAN/SCIENCE PHOTO LIBRARY. / Getty Images

pH is a measure of how acidic or basic a chemical is when it's in aqueous (water) solution. A neutral pH value (neither an acid nor a base) is 7. Substances with a pH greater than 7 up to 14 are considered bases. Chemicals with a pH lower than 7 down to 0 are considered acids. The closer the pH is to 0 or 14, the greater its acidity or basicity, respectively. Here's a list of the approximate pH of some common chemicals.

pH of Common Acids

Fruits and vegetables tend to be acidic. Citrus fruit, in particular, is acidic to the point where it can erode tooth enamel. Milk is often considered to be neutral, since it's only slightly acidic. Milk becomes more acidic over time. The pH of urine and saliva is slightly acidic, around a pH of 6. Human skin, hair, and nails tends to have a pH around 5.

0 - Hydrochloric Acid (HCl)
1.0 - Battery Acid (H2SO4 sulfuric acid) and stomach acid
2.0 - Lemon Juice
2.2 - Vinegar
3.0 - Apples, Soda
3.0 to 3.5 - Sauerkraut
3.5 to 3.9 - Pickles
4.0 - Wine and Beer
4.5 - Tomatoes
4.5 to 5.2 - Bananas
around 5.0 - Acid Rain
5.3 to 5.8 - Bread
5.4 to 6.2 - Red Meat
5.9 - Cheddar Cheese
6.1 to 6.4 - Butter
6.6 - Milk
6.6 to 6.8 - Fish

Neutral pH Chemicals

7.0 - Pure Water

pH of Common Bases

Many common cleaners are basic. Usually, these chemicals have very high pH. Blood is close to neutral, but is slightly basic.

7.0 to 10 - Shampoo
7.4 - Human Blood
around 8 - Seawater
8.3 - Baking Soda (Sodium Bicarbonate)
around 9 - Toothpaste
10.5 - Milk of Magnesia
11.0 - Ammonia
11.5 to 14 - Hair Straightening Chemicals
12.4 - Lime (Calcium Hydroxide)
13.0 - Lye
14.0 - Sodium Hydroxide (NaOH)

How to Measure pH

There are multiple ways to test the pH of substances.

The simplest method is to use pH paper test strips. You can make these yourself using coffee filters and cabbage juice, use Litmus paper, or other test strips. The color of the test strips corresponds to a pH range. Because the color change depends on the type of indicator dye used to coat the paper, the result needs to be compared against a chart of standard.

Another method is to draw a small sample of a substance and apply drops of pH indicator and observe the test change. Many home chemicals are natural pH indicators.

pH test kits are available to test liquids. Usually these are designed for a particular application, like aquaria or swimming pools. pH test kits are fairly accurate, but may be affected by other chemicals in a sample.

The most accurate method of measuring pH is using a pH meter. pH meters are more expensive than test papers or kits and require calibration, so they are generally used in schools and labs.

Note About Safety

Chemicals that have very low or very high pH are often corrosive and can produce chemical burns. It's fine to dilute these chemicals in pure water to test their pH. The value won't be changed, but the risk will be reduced.