Worksheet: Classifying Acids and Bases Based on Dissociation Constants

In this worksheet, we will practice classifying acids and bases as weak or strong based on their dissociation constants.


The relative acid strengths of NH4+ and HCN can be determined by comparing their acid and base dissociation constants, 𝐾a and 𝐾b. HCN has a 𝐾a of 4.9×10 and NH3, the conjugate base of NH4+, has a 𝐾b of 1.8×10. Given that the self-ionization constant of water is 1.0×10, which compound is the stronger acid?

  • AMore information is needed.
  • BNH4+ is the stronger acid.
  • CHCN is the stronger acid.
  • DHCN and NH4+ are equally strong acids.


The odor of vinegar is due to the presence of acetic acid, CHCOH32, a weak acid. For a solution of acetic acid, which of the following is false?

  • A[CHCO]22 > [CHCOH]32
  • B[HO]3+ > [OH]
  • C[HO]3+[CHCO]22
  • D[CHCOH]32 > [HO]3+
  • E[HO]2 > [CHCOH]32


Household ammonia is a solution of the weak base NH3 in water. For a solution of ammonia, which of the following is false?

  • A[NH]3[NH]4+
  • B[OH] > [HO]3+
  • C[NH]3 > [OH]
  • D[HO]2 > [NH]3
  • E[OH][NH]4+


Which base, CHNH32 or (CH)NH32, is the stronger base at 25C? The 𝐾b of CHNH32 at this temperature is 4.4×10 and the 𝐾b of (CH)NH32 is 5.9×10.

  • A(CH)NH32
  • BIt is impossible to tell without knowing at what concentration their basicity is measured.
  • CCHNH32
  • DThey are both amines, and therefore they are equally strong bases.


The active ingredient formed by aspirin in the body is salicylic acid, CHOH(COH)642. The carboxyl group (COH)2 acts as a weak acid. The phenol group (an OH group bonded to an aromatic ring) also acts as an acid, but a much weaker acid.

Which one of the following is false for a 0.001 M aqueous solution of salicylic acid?

  • A[CHO(COH)]>[CHOH(CO)]642642
  • B[CHOH(CO)]>[CHO(COH)]642642
  • C[HO]>[OH]3+
  • D[CHOH(COH)]>[CHO(COH)]642642


Which is the stronger base, (CH)N33 or HBO23? The 𝐾b of (CH)N33 is 6.3×10 and the 𝐾a of HBO33 is 5.4×10.

  • AIt is impossible to tell without knowing at what concentration their basicity is measured.
  • BHBO23
  • C(CH)N33 and HBO23 are equally strong bases.
  • D(CH)N33


A 5.16 g sample of NHCl4 was added to 20.0 mL of 1.00 MNaOH and the resulting solution was diluted to 0.100 L. The 𝐾b of NH3 is 1.8×10. Is the solution acidic, neutral, or basic?

  • AAcidic
  • BBasic
  • CNeutral

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.