Autoionization of Water and pH

Arrange the following solutions in the order of increasing acidity (least acidic to most acidic):

(a) pH = 9.8

(b) pH = 1.2

(c) pH = 4.7

(d) pH = 6.4

Arrange the following solutions in the order of increasing basicity (least basic to most basic):

(a) pOH = 5.2

(b) pOH = 11.6

(c) pOH = 3.4

(d) pOH = 1.9

Calculate the pH for each of the following solutions at 25 ^oC:

(a) [H₃O⁺] = 1.3 x 10^-2 M

(b) [H₃O⁺] = 1.6 x 10^-3 M

(c) [OH^–] = 1.8 x 10^-3 M

 Calculate the [OH^–] of each of the following solutions at 25 ^oC. Identify the solution as neutral, acidic, or basic.

a) [H⁺] = 2.5 x 10^-6 M

b) [H⁺] = 8.3 x 10^-4 M

c) [H⁺] = 4.6 M

d) [H⁺] = 3.9 x 10^-2 M

Given the pH values, calculate [H₃O⁺] and [OH^–] for each solution at 25 ^oC. Identify each solution as neutral, acidic, or basic.

a) pH = 7.20

b) pH = 15.3

c) pH = 4.60

The pH of Strong Acids and Bases

Calculate the pH for each of the following solutions:

(a) 0.15 M HCl

(b) 0.60 M HClO₄

(c) 1.4 M KOH

Calculate the pH of each of the following solutions:

(a) 0.0025 M HI, (b) 0.84 M NaOH

Calculate the pH of the solution prepared by dissolving 24.0 g of HCl in 662 mL of water.

How many grams of KOH is needed to prepare a 680.0 mL solution with a pH of 9.80?

Calculate the pH of the solution prepared by diluting 40.0 mL of 3.00 M HNO₃ with 210.0 mL of water.

The pH of Weak Acids

Calculate the pH of a 0.45 M solution of HCN. K_a (HCN) = 4.9 x 10^-10

Calculate the pH of a 0.74 M solution of acetic acid. K_a (CH₃CO₂H) = 1.7 x 10^-5

0.86 g benzoic acid (C₆H₅CO₂H, K_a = 6.4 x 10^-5) was dissolved in enough water to make 1.0 L of solution. Calculate the pH and concentration of all species present in the solution.

Calculate the pH of a 2.0 M solution of hydrofluoric acid, HF if K_a (HF) = 6.6 x 10^-4

What is the acid ionization constant (K_a) of a weak acid (HA) if its 0.246 M solution has a pH of 2.68?

A solution of nitrous acid (HNO₂, K_a = 7.2 x 10^-4) has a pH of 3.1. What was the initial concentration of nitrous acid in the solution?

Calculate the pH of a 0.40 M H₂S solution given that K_a1 = 1.0 x 10^-7; K_a2 = 1.0 x 10^-19.

The pH of Weak Bases

Explain why all of these are weak bases by writing the equations for their reaction with water and the corresponding expression for K_b.

(a) NH₃ (b)  HCO₃^– (c)  CN- (d) CH₃NH₂ (e) C₅H₅N (f) F^–

Determine the pH of a 0.85 M solution of ammonia (NH₃).

Triethylamine, (C₂H₅)₃N is a common organic weak base with K_b of 4.0 x 10^{-4 .} Calculate [OH^–], [H⁺], and the pH of 0.25 M solution of triethylamine.

Calculate [OH^–], [H⁺], and the pH of 0.40 M solution of caffeine (pK_b = 10.4).

Calculate the percentage of ethyl amine (CH₃CH₂NH₂) that is ionized by reacting with water in its 0.64 molar aqueous solution (K_b = 5.6 x 10^-4).

Morphine is among the most popular alkaloids that are used as pain killers. Like all the others, it contains a nitrogen atom which makes it a weak base. What is the K_b of morphine at a certain temperature if its 0.340 M solution has a pH of 10.9?

The Acid–Base Properties of Salts

For each ion, determine if it acts as a weak base in an aqueous solution. For those that do, write an equation to show why they make the solution basic.

a) Cl^– b) BrO^– c) CN^– d) ClO₃^– e) CH₃CO₂^– f) I^– g) NO₂^– h) F^–

Predict whether the aqueous solutions of the following compounds are acidic, basic, or neutral: (a) KBr (b) FeCl₂, (c) Na₂CO₃, (d) Al(NO₃)₃ (e) KClO₄, (f) Na₂SO₃, (g) NH₄ClO₃

Which of the following salts would produce the most basic aqueous solution?

KF b. NaBr c. NH₄Cl d. MgCl₂ e. Mg(NO₃)₂

Calculate the pH of a 0.74 M solution of NaOBr (K_a HBrO = 2.90 x 10^-9).

Calculate the pH of the 0.26 M solution of NH₄ClO₃ (K_b NH₃ = 1.8 x 10^-5).

Calculate the pH of a 0.35 M solution of KNO₂ (K_a = 4.0 x 10^-4).

Calculate the pH of a 1.0 M solution of sodium acetate (CH₃CO₂Na) considering that the K_a of acetic acid (CH₃CO₂H is 1.7 x 10^-5.