In Bronsted-Lowry theory, what is the role of acids and bases?

• A. Acids donate H+ (protons); bases accept
• B. Acids accept H+; bases donate H+
• C. Acids donate electrons; bases accept electrons
• D. Acids donate H-; bases accept H-

Answer: (A)

In the Bronsted-Lowry view, acids are proton donors and bases are proton acceptors. A reaction is a proton transfer: the acid gives up an H+, and the base takes it. After the transfer, the acid becomes its conjugate base, and the base becomes its conjugate acid. For example, HCl donates a proton to water, forming Cl− and H3O+. This framework works in many solvents, not just in water, and it explains why substances can act as acids or bases depending on the situation. The idea that acids donate electrons or hydride (H−) ions, or that acids accept protons, does not fit this definition.