AP Acid Base Equilibrium Review

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

Which of the following is the conjugate acid of HCO₃^-1?

• H₂CO₃
• CO₃^-2
• H₂CO_3^-1
• CO₃^-1

The salt shown below is

• Acidic
• Basic
• Neutral
• None of the above

Tags

NGSS.HS-PS1-1

What is the [H⁺] if the pH is 4.0?

• 1.0 x 10^-10 M

• 1.0 x 10^-4 M

• 1.0 x 10^-14 M

• 1.0 x 10^-7 M

What is the pOH of a solution that has a pH of 2?

• 10
• 12
• 14
• 1

A solution contains 0.04 M of a weak acid. Calculate the pH of the solution knowing that the K_a for the acid is 1.6 x 10^-7

• It is not possible to solve if the identity of the acid is not known

• 4.1

• 4.9

• Because the Ka is very small, the pH is close to neutral (about 6)

When 200 mL of 2.0 M NaOH(aq) is added to 500 mL of 1.0 M HCl(aq), the pH of the resulting mixture is closest to

• 0.85

• 3.0

• 7.0

• 13.0

A student was testing the pH of two different acid solutions and found them both to have a pH of 3.25. Which of the following must be true?

• Both solutions must be weak acids.

• Both solutions must have the same molarity.

• Both solutions must have the same percent dissociation.

• Both solutions must have the same hydronium ion concentration.

Given 0.10 M solutions of the four weak acids below all with 0.10 M concentration, which will have the greatest percent ionization?

HF (K_a = 7.2 x 10^-4)

HNO₂ (K_a = 4.0 x 10^-4)

HCO₂H (K_a = 1.8 x 10^-4)

HC₃H₅O₃ (K_a = 1.4 x 10^-4)

• HF because its K_a is the largest.

• HF because its molar mass is the smallest.

• HC₃H₅O₃ because its K_a is the smallest.

• HC₃H₅O₃ because its molar mass is the greatest.

Which of the following best approximates the K_a value for this weak acid?

• 1 x 10^–4

• 1 x 10^–5

• 5x 10^–6

• 5 x 10^–7