Which of the following compound pairs, dissolved into solution at equal concentrations, will function as a buffer?

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11ecba2d_121f_5265_a3bf_db8c9c083a8c_MD0008_00 Buffers are solutions that resist changes in pH when small amounts of acid or base are added. Buffers consist of a mixture of either a weak acid and a salt of its conjugate base, or a weak base and a salt of its conjugate acid. The acidic component of a buffer mixture can neutralize any added base, and the basic component of a buffer mixture can neutralize any added acid. As a result, large changes in pH are impeded. For example, acetic acid (CH₃COOH) is a weak acid, and its conjugate base is the acetate anion (CH₃COO⁻). As such, a buffer could be made by mixing equal concentrations of each into solution. A salt such as sodium acetate (CH₃COONa) could function as the source of acetate ions. Once formed, the buffer would establish the following equilibrium: 11ecba2d_121f_7976_a3bf_e717820ce283_MD0008_00 Any strong base (OH⁻) added to the solution would be neutralized by the CH₃COOH to form more acetate ions: 11ecba2d_121f_7977_a3bf_876f81207b11_MD0008_00 Similarly, any strong acid (H₃O⁺) added to the solution would be neutralized by the CH₃COO⁻ to form more CH₃COOH: 11ecba2d_121f_7978_a3bf_7d83a8977144_MD0008_00 Therefore, an aqueous mixture of CH₃COOH and CH₃COONa will function as a buffer. (Choice A) NaNO₃ is the salt of the conjugate base of HNO₃, but HNO₃ is a strong acid and strong acids are not suitable for making buffers. (Choice C) NaBr with NaCN is a mixture of two salts. A buffer requires a weak acid (or a weak base) to be present with the salt of its corresponding conjugate base (or conjugate acid). (Choice D) NaOH is a strong base, and strong bases are not suitable for making buffers. Moreover, NaCl is not the salt of the conjugate acid of NaOH. Educational objective: Buffers are solutions that resist changes in pH when small amounts of acid or base are added. Buffers consist of a mixture of either a weak acid and a salt of its conjugate base, or a weak base and a salt of its conjugate acid.

Which of the Following Compound Pairs, Dissolved into Solution at Equal