The Fine Art of Neutralization

Next to flammable liquid releases, hazmat responders will handle corrosive spills most frequently. Consequently, it behooves responders to know such things about corrosives as the pH scale and safe and efficient forms of product control. One such measure is how to accurately calculate the needed amount of neutralizer to add to an acid spill.

Neutralization is perhaps the most efficient method of mitigating acid spills and the calculations for doing so are relatively simple. Neutralization is a chemical reaction in which water is formed along with a precipitate (salt compound) through the mutual destruction of the ions that characterize acids and bases. This process does not necessarily mean that a solution with a pH of 7.0 will result. Keep in mind that if a strong acid reacts with a weak base the pH will be below 7.0. When a strong base reacts with a weak acid the pH will be above 7.0.

Responders also need to consider the following before employing neutralization;

Heat of reaction
Neutralization will evolve heat because it is an exothermic reaction between acids and bases. It can also evolve gases and splattering that increase risk of exposure to personnel. For these reasons it is best to consider weak neutralizing agents and avoid strong acids or bases such as sodium hydroxide or potassium hydroxide.

Personnel training and protective equipment
Only properly protected and properly trained personnel should attempt neutralization. Neutralization should not be employed for the first time at an acid or base spill.

Expense and disposal
Before neutralization is considered responders need to ask themselves the following questions; What are the costs involved with the process and how will clean-up proceed after the neutralization is complete? Are there better agent alternatives in light of expenses? Finally, will the whole process best be handled by trained and equipped contractors? Is the action by responders necessary, justified, and reasonable? Honest answers are necessary.

If it is decided to conduct a neutralization of an acid spill specific steps should be followed to calculate the approximate amount of neutralizing agent that would be needed. An excellent resource that assists in these calculations is listed at the end of this article. To properly calculate the needed neutralizer many components must be known or approximated such as the identity of the spilled material, the amount of the spill, and the neutralizer that will be utilized. Tables with appropriate information to complete the calculations can be consulted from the resource listed. Using neutralization formulas take the mystery out of the process and the final figure is merely an approximation. In actual practice slightly more neutralizer should be secured for complete neutralization. Be sure to adequately mix the neutralizing agent into all areas of the spill and check with pH paper for the desired range in order to stop the application of neutralizer. Before application begins assure the spill is static and cannot migrate. Always be careful in conducting the neutralization process!


Hazardous Materials Chemistry for the Non-Chemist