Review

of

Acids

HCl Strong Acid HCl → H⁺ + Cl^-

0.10 M 0.10 M

pH = -Log[H⁺] = 1.0 No ICE

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HF Weak Acid HF ⇌ H⁺ + F^-

I 0.10 M 0 0

C x x x

E 0.10 - x x x

small Ka

x² = 3.5 x 10^-4 x = 0.005916 M

0.10

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pH = -Log[0.005916] = 2.23

NaOH Strong Base NaOH → Na⁺ + OH^-

0.20 M 0.20 M

pOH = -Log[OH^-] = 0.70 No ICE

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NH₃ Weak Base NH₃ + H₂O ⇌ NH₄⁺ + OH^-

I 0.20 M 0 0

C x x x

E 0.20 - x x x

small Kb

x² = Kb = Kw = 1.0 x 10^-14 = 1.786 x 10^-5

0.20 Ka 5.6 x 10^-10

x = 0.001890 M

pOH = -Log[0.001890] = 2.73

pH = 11.27

CaO Basic Anhydride CaO + H₂O → Ca(OH)₂

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SO₂ Acid Anhydride SO₂ + H₂O → H₂SO₃

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Salts

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NaCl neutral salt NaCl → Na⁺ + Cl^-

KCN basic salt

CN^- + H₂O ⇌ HCN + OH^-

hydrolysis

NH₄Cl acidic salt

NH₄⁺ + H₂O ⇌ H₃O⁺ + NH₃

hydrolysis

FeCl₃ acidic salt

Fe(H₂O)₆³⁺ ⇌ H⁺ + Fe(H₂O)₅(OH)²⁺

hydrolysis- copy off chart!

Know the pH scale

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0 7 14

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HCl HF NaCl NH₃ NaOH

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Assuming 1M

Buffers Maintain the pH

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Weak Acid + Salt ( conjugate)

HF KF

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HF ⇌ H⁺ + F^-

High Low High

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Indicator Change colour with pH

HInd ⇌ H⁺ + Ind^-

Acid Low Basic

Indicators Change colour with pH

methyl red

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HInd ⇌ H⁺ + Ind^-

red yellow page 7

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@ trans pt [HInd] = [Ind^-] colour is orange

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and Ka = [H⁺]

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pH = 4.8 + 6.0 = 5.4

2

Ka = [H⁺] = 10^-5.4 = 4 x 10^-6

Acid Rain SO₂ NO₂ pH ≤ 5

Normal Rain CO₂ pH = 6

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Amphriprotic H₂C₂O₄ acid

HC₂O₄^- ampriprotic

C₂O₄^2- base

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Is HC₂O₄^- an acid or base?

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Ka (HC₂O₄^-) = 6.4 x 10^-5

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Kb (HC₂O₄^-) = 1.0 x 10^-14 = 1.7 x 10^-13

5.9 x 10^-2 acid

Is NH₄CH₃COO an acid or base?

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Ka (NH₄⁺) = 5.6 x 10^-10

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Kb (CH₃COO^-) = 1.0 x 10^-14 = 5.6 x 10^-10

1.8 x 10^-5 neutral

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100.0 mL 0.100 M H₂SO₄ is mixed with 220.0 mL of 0.100 M NaOH. What is the pH of the resulting solution?

H₂SO₄ + 2NaOH

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0.1000 L x 0.100 mole 0.2200 L x 0.100 mole

1 L 1 L

I 0.0100 mole 0.0220 mole

C 0.0100 mole 0.0200 mole

E 0 mole 0.0020 mole

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[NaOH] = 0.0020 mole = 0.00625 M

0.320 L pOH = 2.20

pH = 11.80

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Complete the reaction and state if the reactants or products are favoured.

HCO₃^- + HSO₃^-

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Base Acid

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HCO₃^- + HSO₃^- ⇌ H₂CO₃ + SO₃^2-

weaker weaker stronger stronger base acid acid base

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Reactants are favoured

Know the Equations

E + H₂O ⇌ H⁺ + OH^-

Kw = [H⁺][OH^-] = 1.0 x 10^-14

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pH = -Log[H⁺] pOH = -Log[OH^-]

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[H⁺] = 10^-pH [OH^-] = 10^-pOH

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pH + pOH = pKw = 14 @ 25 ^oC

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@ other temperatures pure water is always neutral

& [H⁺] = [OH^-] & pH = pOH ≠ 7

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