Module 7 Quizizz

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

A weak acid, HF, is in solution with dissolved sodium fluoride, NaF. If HCl is added, which ion will react with the extra hydrogen ions from the HCl to keep the pH from changing?

• OH^-
• Na⁺
• F^-
• Na^-

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

When citric acid is produced by the cells of an orange and dissolves in water, it produces a relatively small number of hydronium ions. Citric acid is best described as a

• concentrated acid. 
• strong acid. 
• dilute acid.
• weak acid.

Which of the following equimolar solutions could act as a buffer system?

• ClO^-_(aq) / HClO_4(aq)
• H₂PO₄^-_(aq) / H₃PO_4(aq)
• Cl^-_(aq) / HCl_(aq)
• NO₃^- / HNO_3(aq)

A technician has been given two unlabelled basic solutions. One is a weak base & one is a strong base but they have the same pH.  Which of the following statements is true?

• The weak base dissociates 100% and is more concentrated than the strong base.
• The strong base dissociates less than 100% and is more concentrated than the weak base.
• The weak base dissociates less than 100% and is less concentrated than the strong base.
• The strong base dissociates 100% and is less concentrated than the weak base.

Which is the weakest acid?

• HF
• HNO₂
• CH₃COOH
• HClO

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