Common household vinegar is a good choice for neutralizing ammonia. Because ammonia is so prevalent in urine, vinegar is an excellent choice in cleaning up pet accidents and mitigating pet odors. Since ammonia in urine is not pure aqueous ammonia, a mixture of vinegar and water is acceptable for this purpose.
The pH scale measures the strength of acids and bases. Neutral substances, such as water, have a pH of 7. Compounds with a lower pH are acids, and compounds with a higher pH are bases. Ammonia is an alkaline, or basic, chemical made of one nitrogen and three hydrogen atoms. Ammonia occurs naturally in trace amounts when organic material decays. The kidneys also secrete ammonia as a means of neutralizing acid. As a base, ammonia easily gives up electrons and accepts protons. Acids neutralize bases because they accept electrons and give up protons. Aqueous ammonia has a pH of approximately 12, and vinegar has a pH of about 3.
Ammonia itself is a common household cleaner. Caution is necessary when mixing any cleaners because some mixtures, such as ammonia and bleach, release toxic chemicals. Ammonia and vinegar are not likely to release dangerous fumes, but the combination is a neutral solution with little use as a solvent or cleaner.