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Salts neutralization reactions acids bases strong acid+ strong base

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Presentation on theme: "Salts neutralization reactions acids bases strong acid+ strong base"— Presentation transcript:

1 Salts neutralization reactions acids bases strong acid+ strong base non-hydrolyzing salt weak acid+ strong base hydrolyzing salt strong acid+ weak base hydrolyzing salt weak acid+ weak base hydrolyzing salt CH3COOH NaOH 1.00 M 1.00 M 500 mL

2 CH3COOH  CH3COO- + H+ 1.00 M Ka = 1.8 x 10-5 = x2 500 mL 1.00 - x I C
0.00 0.00 C -x +x +x E x x x x = 4.24 x 10-3 = [H+] . pH = 2.37

3 Equivalence Point CH3COOH NaOH 1.00 M mol acid = mol base 1.00 M 500 mL 1.00 mol L x L = mol acid 0.500 mol base 1.00 mol L = L base CH3COOH CH3COO- + H+ + OH- H2O + CH3COO- [CH3COO-] = 0.500 mol = 0.50 M 0.500 L CH3COO- + H2O CH3COOH + OH- strong conjugate base

4 Equivalence Point CH3COOH NaOH 1.00 M 1.00 M 500 mL CH3COO- + H2O CH3COOH + OH- Kb = Kw = 1 x 10-14 = 5.56 x 10-10 1.8 x 10-5 . Ka . x = [OH-] = 1.67 x 10-5 pH = 9.22 5.56 x = [CH3COOH] [OH-] = x2 [CH3COO-] x

5 CH3COOH NaOH 1.00 M 0.100 mol H+ = 0.100 mol OH- 1.00 M 500 mL
add 100 mL 0.500 mol mol = .400 mol CH3COOH = M . 0.600 L 0.100 mol = M CH3COO- 0.600 L . CH3COOH CH3COO- + H+ [CH3COOH] [CH3COO-] [H+] I 0.667 0.167 0.00 Ka = 1.8 x 10-5 = ( x) (x) C -x +x +x (0.667 – x) E x x x x = 7.20 x 10-5 pH = 4.14

6 presence of conjugate base inhibits dissociation
Common ion effect presence of conjugate base inhibits dissociation weak acid or base + conjugate base or acid . . . CH3COOH CH3COO- + H+ . [CH3COOH] [CH3COO-] [H+] I 0.667 0.00 0.00 Ka = 1.8 x 10-5 = (x) (x) C -x +x +x (0.667 – x) E x x x x = 3.46 x 10-3 pH = 2.46

7 Henderson-Hasselbalch Equation
H+ + A- Ka = [H+] [A-] [H+] = Ka [HA] [A-] [HA] - log [H+] = - log Ka + log [A-] [HA] pH = pKa + log [A-] [HA]

8 Henderson-Hasselbalch Equation
half-way point CH3COOH NaOH 1.00 M 0.250 mol H+ = mol OH- 1.00 M 500 mL add 250 mL 0.500 mol mol = .250 mol CH3COOH = M . 0.750 L 0.250 mol = M CH3COO- 0.750 L . Henderson-Hasselbalch Equation pH = pKa + log [A-] [HA] pH = pKa pH = 4.74 + log .333 = 4.74 .333

9 Henderson-Hasselbalch Equation
CH3COOH NaOH 1.00 M 0.375 mol H+ = mol OH- 1.00 M 500 mL add 375 mL 0.500 mol mol = .125 mol CH3COOH = M . 0.875 L 0.375 mol = M CH3COO- 0.875 L . Henderson-Hasselbalch Equation pH = pKa + log [A-] [HA] pH = 4.74 + log .429 = 5.22 .143

10 pH = pKa + log [A-] [HA] Kb = 1.8 x 10-3 What is the pH of 100 mL of a 0.10 M solution of NH3 a) b) c) d) e) 12.63 What volume of 1.00 M HCl is needed to reach the equivalence point? a) 1000 mL b) 100 mL c)10 mL d) 1 mL e) 0.1 mL What is the pH at the equivalence point? a) b) c) 3.25 d) e) What is the pH at the half-way point? a) b) c) 7.00 d) e)


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