Acid-Base ka, kB, pKa, pKb Worksheet

Acid-Base K_a, K_b, pK_a & pK_bWorksheet
1.	Calculate the
	a) [H₃O⁺],
	b) the pH and,
	c) the % dissociation for a 0.50 mol/L HCN solution.
2.	Calculate the
	a) [H₃O⁺],
	b) the pH,
	c) the pOH and,
	d) the % dissociation for a 0.10 mol/L solution of NH₄⁺ derived from a salt such as NH₄NO₃.
3.	Write equations which represent the dissociation of each of these acids or bases in aqueous solution. Use a single arrow in the case of a strong acid or base, and a double arrow to represent the equilibrium condition that exists in the solution of a weak acid or base. Show each step of dissociation for polyprotic acids.
	a) KOH, b) H₃AsO₄, c) HClO₄, d) HCN, e) C₆H₅NH₂ (a weak base)
4.	Benzoic acid, C₆H₅CO₂H, is an organic acid whose sodium salt , C₆H₅CO₂Na, has long been used as a safe food additive to protect beverages and many foods against harmful yeasts and bacteria. The acid is monoprotic. Write the equation for it's K_a.
5.	The pK_a of HCN is 9.21 and that of HF is 3.17. Which is the stronger Bronsted base: CN^- or F^-?
6.	What is the percent ionization in a 0.15 M solution of HF? What is the pH of this solution?
7.	Periodic acid, HIO₄, is an important oxidizing agent and a moderately strong acid. In a 0.10 M solution, [H⁺]=3.8 X 10^-2 mol/L. Calculate the K_a and pK_a for periodic acid.
8.	Barbituric acid, H-Bar, was discovered by Adolph von Baeyer (of Baeyer aspirin fame) and maned after a friend, Barbara. It is the parent compound of widely used sleeping drugs, the barbiturates. Its pK_a is 4.01. What will be the [H⁺] and pH of a 0.050 M solution of H-Bar?
9.	Hydrazine, N₂H₄, has been used as a rocket fuel. Like ammonia, it is a Bronsted base. A 0.15 M solution has a pH of 10.70. What is the K_b and pK_b for hydrazine and the pK_a of its conjugate acid?
10.	Codeine, a cough suppressant extracted from crude opium, is a weak base with a pK_b of 5.79. What will be the pH of a 0.020 M solution of codeine? (Use Cod as a symbol for codeine.)
11.	Quinine, an important drug in treating malaria, is a weak Bronsted base that we may represent as Qu. At 25^oC its pK_b is 5.48. To make it more soluble in water, it is put into a solution as its conjugate acid, which we may represent as H-QuCl. What is the calculated pH of a 0.15 M solution of H-Qu⁺?
12.	Nicotinic acid, HC₂H₄NO₂ is a B vitamin. It is also a weak acid with K_a=1.4 x 10^-5. What is the [H⁺] and the pH of a 0.010 M solution?
13.	Write the equilibrium equations and the equations for K_b for each of the following Bronsted bases.
	(a) CN^- (cyanide ion)
	(b) C₂H₃O₂^- (acetate ion)
	(c) C₆H₅NH₂ (aniline)
	(d) H₂O
14.	Few substances are more effective in relieving intense pain then Morphine. Morphine is an alkaloid (an alkali-like compound obtained from plants) and alkaloids are all weak bases. In 0.010 M morphine, the pH is 10.10. Calculate the K_b for morphine.

Answers