Chapter 16 Quizizz 1

The K_a, acid dissociation constant, for an acid is 9 x 10^-4 at room temperature. At this temperature, what is the approximate percent dissociation of the acid in a 1.0 M solution?

• 0.03%

• 0.09%

• 3%

• 5%

Calculate the pH of a 0.70 M solution of HF. (HF has a K_a of 7.2 x 10^-4)

• 12.4

• 10.6

• 1.7

• 6.4

A weak acid is found to have a [H⁺] at equilibrium of 1.54x10^-4 M. If the weak acid has an initial concentration of 0.70 M, determine the % dissociation.

• 0.13 %

• 0.084 %

• 0.041 %

• 0.022 %

Phosphoric acid, H₃PO₄, dissociates stepwise as shown below.

H₃PO₄ <-> H⁺ + H₂PO₄^-

H₂PO₄^- <-> H⁺ + HPO₄^2-

HPO₄^2- <-> H⁺ + PO₄^3-

Which of the following is an acid followed by its conjugate base?

• HPO₄^2-, H₂PO₄^-

• H₂PO₄^-, PO₄^3-

• H₃PO₄, HPO₄^2-

• H₂PO₄^-, HPO₄^2-

Which is the weakest acid?

• HF

• HNO₂

• CH₃COOH

• HClO

• HCN

The larger the Ka value for a weak acid, the ______________ the ionization of the weak acid in water.

• lower

• greater

What is the concentration of HC₂O₄^– in a 0.300 M oxalic acid, H₂C₂O₄, solution? For oxalic acid, Ka₁ = 5.6 × 10^–2 .

• 0.10 M

• 0.39 M

• 0.07 M

• 0.059 M

Consider the general equation for an acid in water:
HA(aq) + H₂O ↔ H₃O⁺ + A^-
If there is a lot of product, what does that tell you about the acid?

• K_a > 1  Strong acid
• K_a > 1  Weak acid
• K_a < 1  Strong acid
• K_a < 1  Weak acid