Worksheet: Combining Acid and Base Equilibria

In this worksheet, we will practice using suitable approximations to calculate the concentrations of species in multiple interacting equilibria.

Q1:

Hydrogen telluride ( H T e ) 2 is a diprotic acid with 𝐾 a 1 = 2 . 3 × 1 0 and 𝐾 a 2 = 1 . 3 × 1 0 .

What is 𝐾 b for the reaction in which H T e functions as a base in water?

  • A 1 . 3 × 1 0
  • B 2 . 3 × 1 0
  • C 7 . 7 × 1 0
  • D 4 . 3 × 1 0
  • E 4 . 0 × 1 0

Q2:

An aqueous solution has an initial N H 3 concentration of 0.115 M and an initial C H N H 6 5 2 concentration of 0.100 M. The 𝐾 b of N H 3 is 1 . 8 × 1 0 5 , the 𝐾 b of C H N H 6 5 2 is 4 . 6 × 1 0 1 0 , and the self-ionization of water, 𝐾 w , is 1 . 0 × 1 0 1 4 . Calculate to 2 significant figures the concentration of C H N H 6 5 3 + at equilibrium.

  • A 0.14 M
  • B 0.10 M
  • C 6 . 9 × 1 0 1 2 M
  • D 3 . 2 × 1 0 8 M
  • E 1 . 4 × 1 0 3 M

Q3:

A solution has an initial H N O 2 concentration of 0.134 M and an initial H B r O concentration of 0.120 M. The 𝐾 a of H N O 2 is 4 . 5 0 × 1 0 4 and the 𝐾 a of H B r O is 2 . 0 0 × 1 0 9 . Calculate the equilibrium concentration of B r O in the solution at equilibrium.

  • A 3 . 5 5 × 1 0 8 M
  • B 3 . 0 9 × 1 0 8 M
  • C 3 . 7 6 × 1 0 8 M
  • D 3 . 1 8 × 1 0 8 M
  • E 3 . 6 5 × 1 0 8 M

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