STEHN Acid base Equilibrium

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 a conjugate acid/base pair?

• HCl/OCl^-
• H₂SO₄/SO₄^2-
• NH₄⁺/NH₃
• H₃O⁺/OH^-

The pH of a solution at 25^ₒC in which [OH-] = 3.9 x 10^-5M is:

• 4.41
• 3.90
• 9.59
• 4.80

Calculate the pH of a 0.47M NH₃ (K_b = 1.8 x 10^-5) solution.

• 2.54
• 8.93
• 5.07
• 11.46

Which of the following is not a strong acid?

• nitric
• sulfuric
• perchloric
• hydrofluoric

Calculate the [H⁺] in a solution that has a pH of 2.73.

• 5.4 x 10^-12 M
• 1.9 x 10^-3 M
• 2.7 M
• 11.3 M

Which of the following shows the correct conjugate acid base pair?

• CH₃COOH (acid) / H₂O (conjugate base)

• CH₃COOH (acid) / CH₃COO^- (conjugate base)

• H₂O (base) / H⁺(conjugate acid)

• H₂O (base) / CH₃COOH (conjugate acid)

For this reaction :

B(aq) + H₂O(l) ⇌ BH⁺(aq) + OH^-(aq)

Which one can act as an acid ?

• B(aq) and BH⁺(aq)

• B(aq) and BH⁺(aq)

• H₂O(l) and BH⁺(aq)

• H₂O(l) and OH^-(aq)

dissociation of weak acid, HA, is represented by following equation :

HA(aq) + H₂O(l) ⇌ H₃O⁺(aq) + A^-(aq)

The equilibrium constant for this reaction is represented by K_a . Which of the following equation represents expression of equilibrium constant, K_a?

• 
• 
• 
• 

What is the pH of a solution if [OH^-] = 1.0 x 10^-5M?

• 5.00
• 7.00
• 9.00
• 11.00