Brønsted–Lowry Proton Transfer and Water Autoionization

All flashcards

Brønsted–Lowry acid

A species that donates a proton, H⁺, to another species.

Conjugate acid-base partners

Species related by the gain or loss of one proton.

Water autoionization

The proton-transfer reaction in which water forms hydronium and hydroxide.

Ion-product constant for water, $K_w$

At a given temperature, the product of hydronium and hydroxide concentrations in aqueous solution.

Temperature dependence of $K_w$

Because water autoionization is endothermic, $K_w$ increases as temperature rises.

Quiz questions

1. In the Brønsted–Lowry model, what defines an acid-base reaction?Answer: A proton transfers from a donor to an acceptor.
2. In $H_2O + NH_3 ightleftharpoons OH^- + NH_4^+$, which role does $NH_3$ play?Answer: It accepts a proton and becomes $NH_4^+$.
3. Which equation represents the autoionization of liquid water?Answer: $2H_2O(l) ightleftharpoons H_3O^+(aq) + OH^-(aq)$
4. At 25 °C, what is the ion-product constant for water?Answer: $1.0 \times 10^{-14}$
5. What happens to $K_w$ when the temperature of water increases?Answer: It increases because water autoionization is endothermic.