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It is Wednesday. The first homework is due. Place it on the bench in front.
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Acids and bases of varying strengths.
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Acids and bases of varying strengths.
Strong acid = 100% ionization Strong acid = 100% donation of acidic proton.
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HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq)
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HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq)
[H3O+][Cl-] K = [HCl]
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HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq)
[H3O+][Cl-] large K = = [HCl]
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Generic acid HA(aq) + H2O(l) H3O+(aq) + A-(aq)
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Generic acid HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = acidity constant = Ka [HA]
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Generic acid HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = acidity constant = Ka [HA] -log10 Ka = pKa
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Acid Ka pKa HI -11 HCl -7 H2SO -2 CH3COOH x Table page 332
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Base strength
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Base strength Inversely related to strength of conjugate acid.
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Base strength Inversely related to strength of conjugate acid. H2O(l) + B(aq) HB+(aq) + OH-(aq) conjugate acid
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H2O(l) + B(aq) HB+(aq) + OH-(aq)
[HB+][OH-] = Kb = basicity constant [B]
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[HB+][OH-] = Kb = basicity constant [B] [H3O+][B] = acidity constant = Ka [HB+] [H3O+][OH-] = Kw
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[HB+][OH-] = Kb = basicity constant [B] [H3O+][B] = acidity constant = Ka [HB+] Conjugate acid [H3O+][OH-] = Kw KbKa = Kw
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[HB+][OH-] = Kb = basicity constant [B] [H3O+][B] = acidity constant = Ka [HB+] [H3O+][OH-] = Kw KbKa = Kw pKb + pKa = pKw
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KbKa = Kw pKb + pKa = pKw Expressions can be used for any conjugate acid-base pair in water.
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Indicators : Usually a weak organic acid that has a color different from its conjugate base.
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Indicators : Usually a weak organic acid that has a color different from its conjugate base. HA + H2O H3O+ + A-
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phenolphthalein
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Indicators : Usually a weak organic acid that has a color different from its conjugate base. + H2O H3O+ + A-
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phenolphthalein
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Equilibria with weak acids
and weak bases.
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Equilibria with weak acids
and weak bases. Weak acid:
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Equilibria with weak acids
and weak bases. Weak acid: Ka < 1
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Equilibria with weak acids
and weak bases. Weak acid: Ka < 1 [H3O+][A-] Ka = [HA]
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Equilibria with weak acids
and weak bases. Weak acid: Ka < 1 Ka (H3O+) = 1
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Equilibria with weak acids
and weak bases. Weak acid: Ka < 1 Ka (H3O+) = 1 Why is a weak acid weak?
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HCl Ka strong HF Ka = 6.6 x weak
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HCl Ka strong HF Ka = 6.6 x weak HF more ionic than HCl
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HCl Ka strong HF Ka = 6.6 x weak HF more ionic than HCl Relative Kas show that HF holds proton more strongly than HCl
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HCl Ka strong HF Ka = 6.6 x weak HF more ionic than HCl Relative Kas show that HF holds proton more strongly than HCl Electrostatic attraction for H+ stronger for F- than for Cl-.
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Organic acids Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Organic acids Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1 The more stable the conjugate base, the stronger the acid.
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Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Ka CH3COOH x 10-5 CH3CH2COOH x 10-5 CCl3COOH x 10-1
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Equilibria with weak acids
and weak bases. HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = Ka [HA]
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HA(aq) + H2O(l) H3O+(aq) + A-(aq)
= Ka [HA]
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HA(aq) + H2O(l) H3O+(aq) + A-(aq)
= Ka [HA] CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq)
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HA(aq) + H2O(l) H3O+(aq) + A-(aq)
= Ka [HA] CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) Ka = 1.8 x 10-5
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CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) Ka = 1.8 x 10-5 1 mol CH3COOH 1 L water solution
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CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) Ka = 1.8 x 10-5 1 mol CH3COOH Calculate pH 1 L water solution
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change Eq.
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq.
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y [H3O+][A-] = Ka [HA]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y [H3O+][A-] [H3O+][CH3COO-] = Ka [HA] [CH3COOH]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y [H3O+][CH3COO-] = 1.8 x 10-5 [CH3COOH]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y (y)(y) [H3O+][CH3COO-] = 1.8 x 10-5 = (1-y) [CH3COOH]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y (y)(y) (y2) 1.8 x 10-5 = = (1-y) (1-y)
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y (y)(y) (y2) 1.8 x 10-5 = = (1-y) (1-y) y << 1
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y (y)(y) (y2) 1.8 x 10-5 = = (1-y) (1-y) y << 1 1-y 1
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y (y)(y) (y2) 1.8 x 10-5 = = = y2 (1-y) (1-y) y << 1 1-y 1
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y 1.8 x 10-5 = y2 y = 4.24 x 10-3
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y 1.8 x 10-5 = y2 y = 4.24 x 10-3 -log x 10-3 =
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y 1.8 x 10-5 = y2 y = 4.24 x 10-3 -log x 10-3 = 2.37 = pH
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y y = 4.24 x 10-3 What is the fraction of acid ionized?
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y y = 4.24 x 10-3 What is the fraction of acid ionized? [A-] [HA]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y y = 4.24 x 10-3 What is the fraction of acid ionized? [A-] 4.24 x 10-3 = [HA] 1.0
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. 1.0 -y y y y = 4.24 x 10-3 What is the percent of acid ionized? [A-] 4.24 x 10-3 X 100% = 0.42% = [HA] 1.0
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y Calculate % ionization for M
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y (y2) (y)(y) = 1.8 x 10-5 = ( y) ( y) [A-] [HA]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y (y2) (y)(y) = 1.8 x 10-5 = (0.0001) (0.0001) [A-] [HA]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y (y2) (y)(y) = 1.8 x 10-5 = (0.0001) (0.0001) [A-] y2 = 1.8 x 10-9 [HA]
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y (y2) (y)(y) = 1.8 x 10-5 = (0.0001) (0.0001) [A-] y2 = 1.8 x 10-9 [HA] y = 4.2 x 10-5
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y (y2) (y)(y) = 1.8 x 10-5 = (0.0001) (0.0001) [A-] 4.2 x 10-5 y = 4.2 x 10-5 = 1 x 10-4 42% [HA]
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1 x 10-4 and 4.2 x 10-5 do not differ enough to ignore y.
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[M] [CH3COOH] [H3O+] [CH3COO-] initial change -y y y Eq. y y y (y2) (y)(y) 1.8 x 10-5 = = ( y) ( y) 34% Full solution: pg 342
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1.0 M CH3COOH % ionized M CH3COOH % ionized
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1.0 M CH3COOH % ionized M CH3COOH % ionized [A-] = [HA]
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1.0 M CH3COOH % ionized [A-] = 4.2 x 10-3 M M CH3COOH % ionized [A-] = 3.4 x 10-5 M [A-] = [HA]
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1.0 M CH3COOH % ionized [A-] = 4.2 x 10-3 M M CH3COOH % ionized [A-] = 3.4 x 10-5 M [A-] [A-] 10-2 = [HA] [HA] 10-4
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Problem 29: Calculate pH of 0.35 M solution of propionic acid.
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Problem 29: Calculate pH of 0.35 M solution of propionic acid. Ka = 1.3 x 10-5 Table 8-2
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Problem 29: Calculate pH of 0.35 M solution of propionic acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq)
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Problem 29: Calculate pH of 0.35 M solution of propionic acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) [HA] = 0.35 M
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) [HA] = 0.35 M [H3O+][A-] = Ka [HA]
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) [HA] = 0.35 M [H3O+][A-] (x2) = Ka = [HA] [HA]
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) [HA] = 0.35 M x2 = [HA] Ka
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) [HA] = 0.35 M x2 = [HA] Ka = 0.35 x 1.3 x 10-5 =
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) [HA] = 0.35 M x2 = [HA] Ka = 0.35 x 1.3 x 10-5 = 4.55 x 10-4
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) x2 = [HA] Ka = 0.35 x 1.3 x 10-5 = 4.55 x 10-4 x = 4.55 x 10-4
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) x2 = [HA] Ka = 0.35 x 1.3 x 10-5 = 4.55 x 10-4 x = 4.55 x 10-4 = 2.13 x 10-3
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) x2 = [HA] Ka = 0.35 x 1.3 x 10-5 = 4.55 x 10-4 4.55 x 10-4 = 2.13 x 10-3 x = -log x 10-3 =
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Calculate pH of 0.35 M solution of propionic
acid. Ka = 1.3 x 10-5 Table 8-2 HA(aq) + H2O(l) H3O+(aq) + A-(aq) x2 = [HA] Ka = 0.35 x 1.3 x 10-5 = 4.55 x 10-4 4.55 x 10-4 = 2.13 x 10-3 x = -log x 10-3 = 2.67
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Equilibria involving weak bases
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Equilibria involving weak bases
H2O(l) + B(aq) OH-(aq) + HB+(aq)
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Equilibria involving weak bases
H2O(l) + B(aq) OH-(aq) + HB+(aq) Acid base base acid2
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Equilibria involving weak bases
H2O(l) + B(aq) OH-(aq) + HB+(aq) Acid base base acid2 [OH-][HB+] = Kb [B]
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Equilibria involving weak bases
H2O(l) + B(aq) OH-(aq) + HB+(aq) Acid base base acid2 [OH-][HB+] = Kb [B] Weak base: Kb < 1
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 Kb = ?
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 Kb = ? KaKb = Kw
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 Kw Kb = Ka
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 Kw Kb = Ka
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 Kw Kb = Ka Table page 332: Ka = 5.6 x 10-10
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 1 x 10-14 Kw Kb = = 5.6 x 10-10 Ka
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Equilibria involving weak bases
H2O(l) + NH3(aq) OH-(aq) + NH4+(aq) Acid base base acid2 1 x 10-14 Kw Kb = = = 1.8 x 10-5 5.6 x 10-10 Ka
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Hydrolysis
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Hydrolysis The reaction of water with an ion resulting in a change in the [H3O+]- [OH-] balance.
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Hydrolysis The reaction of water with an ion resulting in a change in the [H3O+]- [OH-] balance. Hydrolysis of anions raises pH.
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Hydrolysis The reaction of water with an ion resulting in a change in the [H3O+]- [OH-] balance. Hydrolysis of anions raises pH. Hydrolysis of cations lowers pH.
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq)
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) Ka (HF) = 6.6 x 10-4
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) Ka (HF) = 6.6 x 10-4 [HF][OH-] Kb = [F-]
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) Ka (HF) = 6.6 x 10-4 [HF][OH-] Kb = [F-] pH M NaF
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) Ka (HF) = 6.6 x 10-4 [HF][OH-] Kw = Kb = [F-] Ka pH M NaF
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) Ka (HF) = 6.6 x 10-4 [HF][OH-] Kw [F-]Kw = [OH-]2 = [F-] Ka Ka pH M NaF
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) Ka (HF) = 6.6 x 10-4 [F-]Kw (0.095)(1 x 10-14) [OH-]2 = = (6.6 x 10-4) Ka pH M NaF
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) [F-]Kw (0.095)(1 x 10-14) = = = [OH-]2 (6.6 x 10-4) Ka
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) [F-]Kw (0.095)(1 x 10-14) = [OH-]2 = = (6.6 x 10-4) Ka 1.44 x 10-12 [OH-]2 =
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) [F-]Kw (0.095)(1 x 10-14) = [OH-]2 = = (6.6 x 10-4) Ka 1.44 x 10-12 [OH-]2 = [OH-] = 1.2 x 10-6
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) [OH-] = 1.2 x 10-6 1 x 10-14 [H3O+] = = 1.2 x 10-6
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) [OH-] = 1.2 x 10-6 1 x 10-14 8.34 x 10-9 [H3O+] = = 1.2 x 10-6
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) [OH-] = 1.2 x 10-6 1 x 10-14 8.34 x 10-9 [H3O+] = = 1.2 x 10-6 -log10 (8.34 x 10-9) = 8.08
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Hydrolysis H2O(l) + F-(aq) HF(aq) + OH-(aq) pH = 8.08
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It is Wednesday. The first homework is due. Place it on the bench in front.
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