AP Chemistry 4.8: Brønsted-Lowry Acids and Bases

Practice AP Chemistry questions on identifying Brønsted-Lowry acids, bases, and conjugate pairs, then representing aqueous proton-transfer reactions with balanced net ionic…

Exam points

Explain how molecular structure, bonding and intermolecular forces determine physical properties of substances.
Apply particle-level models to predict polarity, solubility and phase behavior from molecular interactions.

[Maximum number: 1]

Answer the following questions about the glycolate ion, $\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{3}{ }^{-}$ , which acts as a base in

aqueous solution. A Lewis diagram for the ion is provided.

Figure for Question 4.8.A—Identify species as BrønstedLowry acids, bases, and/or conjugate acid-base pairs, based on proton-transfer… question 1 — AP Chemistry

On the Lewis diagram in part A, circle the atom that accepts the proton when the glycolate

ion reacts with water.

When the glycolate ion reacts with water, it forms glycolic acid, $\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{3}$ , according to the

following equation. The $K_{b}$ expression for the reaction is provided.

\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{3}^{-}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftarrows \mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{3}(a q)+\mathrm{OH}^{-}(a q) \quad K_{b}=\frac{\left[\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{3}\right]\left[\mathrm{OH}^{-}\right]}{\left[\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{3}^{-}\right]}

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4.8.A—Identify species as BrønstedLowry acids, bases, and/or conjugate acid-base pairs, based on proton-transfer… question 1