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Neutralizing Acids and Bases

Quick Tips #148

Neutralize acids, bases or caustic material during a spill cleanup to help keep the work environment safe. Neutralization helps make material safer to handle and helps decrease the cost of disposal. Strong acids and bases can be corrosive to many surfaces, including skin.

The best way to measure a caustic material is to take the pH of the solution. This can be accomplished with pH paper, chemical indicators or pH meters.

pH is the measurement of hydrogen ion concentration [H+] in solution. To calculate the pH of a solution, use the following formula:

pH = log10 1 / [H+]

For example, if the hydrogen ion concentration is 1 x 10-3 moles/liter, the pH would be 3. The pH scale measures from 0 to 14. Chemicals with a pH of 0-3 are considered strong acids. Chemicals with a pH of 12-14 are considered strong bases. To be considered neutral, a chemical must have a pH of 7.

"Acid" comes from the Latin word "acidus," meaning sour. Acids typically will have a sour taste and a pH of less than 7. To neutralize them, you need to use a weak base. There are two types of acids: mineral (inorganic) acids such as sulfuric, hydrochloric or nitric, and carboxylic (organic) acids such as formic or acetic.

Bases have a bitter or astringent taste and a pH greater than 7. They are neutralized by using a weak acid. Bases are also called alkaline compounds. Some examples of bases are sodium hydroxide, potassium hydroxide and ammonia.

There are many different products available on the market that aid in the neutralization of acids and bases. They can be as simple as a bag of citric acid or sodium sesquicarbonate, or as complex as a solidifier and a neutralizer combined.

When neutralization occurs, the acid and base react, forming water and salt. If the acid and base are both very strong (such as concentrated hydrochloric acid and concentrated sodium hydroxide), a violent reaction will occur. This is why most neutralizers are very weak — to keep the reaction at a slow pace. Even with the neutralization products, heat and gas can evolve, so take the proper precautions recommended by the neutralizer manufacturer.

Most neutralizers provide an estimated volume of acid/base that their product will neutralize. It can take a large amount of the product to neutralize an acid or base, especially if it is concentrated. Some neutralizers have a built-in color indicator to let you know when the spill is neutral. Others require you to check the pH until it is neutral. Some neutralizers also solidify the spill as they neutralize to make the spill easier to pick up. See the comparison charts to learn what quantity of common acids and bases each product will neutralize.


Ionization: Occurs as the result of dissociation of atoms of a molecule in solution, e.g. NaCl -> Na+ + Cl-

Ions: Molecules which, by loss or gain of electrons, have acquired a net electric charge.

Mole: The quantity that contains the same number of particles that are contained in 12 grams of carbon-12. The number is 6.02 x 1023. The atomic weight is the number of grams of an element in one mole.

pH: The concentration of hydrogen ion in solution.

Salt: An ionic compound containing a positive ion other than the hydrogen ion (H+) and a negative ion other than the hydroxide ion (OH-) or the oxide ion O2-).


Chart A

Gallons of Acid Neutralized
Acid Spill-X-A®
2.5 lbs.
3.3 lbs.
Spilfyter® Dry Acid
2.0 lbs.
Acetic 99% .30 .40 .25
Hydrochloric 37% .27 .50 .31
Hydrofluoric 49% .25 * *
Nitric 70% .55 .40 *
Perchloric 70% .29 .53 *
Phosphoric 85% .30 .13 .10
Sulfuric 93% .30 .19 .27


Chart B

Gallons of Base Neutralized
Base Spill-X-C®
2 lbs.
4.95 lbs.
Spilfyter® Dry Base
2.0 lbs.
Ammonium Hydroxide .41 .56 .25
Potassium Hydroxide .27 .42 .27
Sodium Hydroxide .17 .26 .18

* Not Applicable



(Rev. 1/2013)

Find even more information you can use to help make informed decisions about the regulatory issues you face in your workplace every day. View all Quick Tips Technical Resources at

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