When an acid reacts with a base, what forms?

• A. Salt forms
• B. Water forms
• C. Gas forms
• D. Precipitate forms

Answer: (A)

Acid–base reactions neutralize each other and rearrange ions to form new substances. The hydrogen ion from the acid meets the hydroxide ion from the base to make water, while the remaining ions—the base’s positive ion and the acid’s negative ion—come together to form a salt. Because the core change is the pairing of those ions into a crystalline or dissolved ionic compound, a salt is what you end up with. Water is commonly produced as well, especially in aqueous solutions, but the substance that reflects the ion pairs created by the reaction is the salt. Gas or precipitate would only occur in special cases, not in the typical neutralization.