I- 11-1 10 10.5 H 3 O + (aq) + OH (aq) + Na + (aq) + Cl (aq) Na + (aq) + Cl (aq) + 2H 2 O(l) - or - [A] V A = [B] V B 22 mol dm 3 equiv dm 3 - H 2 SO 4 (aq) + 2NaOH(aq) 2Na + (aq) + SO 4 2 (aq) + 2H 2 O(l) 2[H 2 SO 4 ] V H2 SO 4 = [NaOH] V NaOH ph = 7 ph 0.1 mol dm 3 10 cm 3 11-2 1) V NaOH = 9 cm 3 n HCl = 1 10 3 9 10 4 = 1 10 4 mol, V = 0.019 dm 3 [H 3 O + ] = 1 10 4 mol 0.019 dm 3 = 5.26 10 3 mol dm 3, ph = 2.28 2) V NaOH = 9.9 cm 3 n HCl = 1 10 3 9.9 10 4 = 1 10 5 mol, V = 0.0199 dm 3 [H 3 O + ] = 1 10 5 mol 0.0199 dm 3 = 5.03 10 4 mol dm 3, ph = 3.30 3) V NaOH = 10.1 cm 3 n NaOH = 1.01 10 3 1 10 3 = 1 10 5 mol, V = 0.0201 dm 3 [OH ] = 1 10 5 mol 0.0201 dm 3 = 4.98 10 4 mol dm 3 ph = 14 poh = 14 3.30 = 10.70 4) V NaOH = 11 cm 3 n NaOH = 1.1 10 3 1 10 3 = 1 10 4 mol, V = 0.021 dm 3 [OH ] = 1 10 4 mol 0.021 dm 3 = 4.76 10 3 mol dm 3 ph = 14 poh = 14 2.32 = 11.68 ph 1
11-3 10.6 ph CH 3 COOH(aq) + NaOH(aq) CH 3 COO (aq) + Na + (aq) + H 2 O(l) CH 3 COO (aq) + H 2 O(l) CH 3 COOH(aq) + OH (aq) K h = [CH 3 COOH][OH ] [CH 3 COO ] = [CH 3 COOH][OH ][H 3 O + ] [CH 3 COO ][H 3 O + = ] K a = 5.71 10 10 mol dm 3 K h K b 2H 2 O(l) H 3 O + (aq) + OH (aq) 0.1 mol dm 3 10 cm 3 20 cm 3 [CH 3 COO ] = 0.05 mol dm 3, [CH 3 COOH] = [OH ] [OH ] 2 = K h [CH 3 COO ] = (5.71 10 10 mol dm 3 ) (0.05 mol dm 3 ) [OH ] = 5.34 10 6 mol dm 3, ph = 14 5.27 = 8.73 11-4 ph CH 3 COOH(aq) + NaOH(aq) CH 3 COO (aq) + Na + (aq) + H 2 O(l) (0.1 mol dm 3, 10 cm 3 ) (0.1 mol dm 3 ) 1) V NaOH = 9 cm 3 K a = [H 3O + ][CH 3 COO ] = [H 3 O + ] 9 [CH 3 COOH] [H 3 O + ] = K a / 9 = 1.94 10 6 mol dm 3 ph = 5.71 2) V NaOH = 10 cm 3, ph = 8.73 3) V NaOH = 11 cm 3 [OH ] = 1 10 4 mol 0.021 dm 3 = 4.76 10 3 mol dm 3 ph = 14 poh = 14 2.32 = 11.68 ph (a) 2
11-5 NH 3 HCl ph NH 3 (aq) + HCl(aq) NH 4 + (aq) + Cl (aq) NH 4 + (aq) + H 2 O(l) H 3 O + (aq) + NH 3 (aq) K h = [H 3 O+ ][NH 3 ] [NH 4 + ] = 5.6 10 10 mol dm 3 = [H 3 O+ ][OH ][NH 3 ] [NH + 4 ][OH = ] K b 0.1 mol dm 3 10 cm 3 20 cm 3 K h K a [NH 4 + ] = 0.05 mol dm 3, [NH 3 ] = [H 3 O + ] [H 3 O + ] 2 = K h [NH 4 + ] = (5.6 10 10 mol dm 3 ) (0.05 mol dm 3 ) [H 3 O + ] = 5.3 10 6 mol dm 3, ph = 5.3 ph (b) 11-6 CH 3 COONahydrolysis h K h CH 3 COONa CH 3 COO (aq) + Na + (aq) [c 0 (mol dm 3 )] CH 3 COO (aq) + H 2 O(l) CH 3 COOH(aq) + OH (aq) c 0 (1 h) c 0 h c 0 h K h = [CH 3 COOH][OH ] [CH 3 COO ] = [CH 3 COOH][OH ][H 3 O + ] [CH 3 COO ][H 3 O + = ] K a K a = [CH 3COO ][H + ], = [H 3 O + ][OH ] [CH 3 COOH] K h = (c 0 h)2 c 0 (1 h) = c 0 h2 1 h c 0 h2 (h << 1) ( ) h K h K h K b K h K b h = K h c 0 = K a c 0 (K h = / K a ) h [OH ] = c 0 h = K h c 0 = c 0 K a 3 [OH ] [H 3 O + ] = [OH ] = K a c 0 ph = log[h 3 O + ] = (1 / 2)(p + pk a + logc 0 ) at 25 o C, ph = 7 + (1 / 2)(pK a + logc 0 ) [H 3 O + ] ph 3
hydrolysis h K h NH 4 + 11-7 NH 4 Cl NH 4 + (aq) + Cl (aq) [c 0 (mol dm 3 )] NH 4 + (aq) + H 2 O(l) H 3 O + (aq) + NH 3 (aq) c 0 (1 h) c 0 h c 0 h K h = [H 3 O+ ][NH 3 ] [NH 4 + ] = [H 3 O+ ][OH ][NH 3 ] [NH + 4 ][OH = ] K b K b = [NH 4 + ][OH ], = [H 3 O + ][OH ] [NH 3 ] K h = (c 0 h)2 c 0 (1 h) = c 0 h2 1 h c 0 h2 (h << 1) ( ) h K h K h K a K h K a h = K h c 0 = K b c 0 (K h = / K b ) h [H 3 O + ] = c 0 h = K h c 0 = c 0 K b 5 [H 3 O + ] ph = log[h 3 O + ] = (1 / 2)[p (pk b + logc 0 )] at 25 o C, ph = 7 (1 / 2)(pK b + log c 0 ) ph 11-8 10.7 ph ph 10.4 ph 4
phindicator 11-9 InH(aq) + H 2 O(l) H 3 O + (aq) + In (aq) K a = [H 3O + ][In ] [InH] at [InH] = [In ] 0.1 < [In ] [InH] = K a [H 3 O + ] < 10 pk a = 3.46 (K a = 3.47 10 4 mol dm 3 ) [H 3 O + ] = K a = 10 3.46 = 10 4 10 0.54 = 3.47( 3.5) 10 4 mol dm 3 [H 3 O + ] > 3.5 10 4 mol dm 3 (= K a ) [InH] > [In ] [H 3 O + ] < 3.5 10 4 mol dm 3 (= K a ) [InH] < [In ] ph = 3.4 6 [H 3 O + ] 10K a > [H 3 O + ] > 0.1K a 2.46 < ph < 4.46 (pk a ± 1) 11-10 HCl NaOH ph 10.2 pk a ± 1 5
11-11 10.8 ph ph 1 dm 3 1x10 4 mol (= 0.00365 g) ph = 4 1x10 4 mol (= 0.0040 g) ph = 10 ph = 7pH ±3 1 CH 3 COOH + CH 3 COONa 2 2 NH 3 + NH 4 Cl 2 ph (a) ph [NH 3 ] = [NH 4+ ] = 0.1 mol dm 3, ph = 9.25 (b) 1 dm 3 1x10 4 mol ph = 9.25 (c) 1 dm 3 1x10 4 mol ph = 9.25 12-14 11-12 2 NH 3 + NH 4 Cl NH 3 NH 4 Cl- NH 4 Cl NH 4 + (aq) + Cl (aq) NH 3 (aq) + H 2 O(l) NH 4 + (aq) + OH (aq) K b = [NH 4 + ][OH ], [NH 3 ([NH 3 ] = c base, [NH + 4 ] = c salt ) ] [H 3 O + ], ph NH 4 + [OH ] = K b [NH 3] [NH 4 + ] = K b c base c salt [H 3 O + ] = [OH ] = [NH 4 + ] K b [NH 3 ] = K a [NH 4 + ] [NH 3 ] = K a c salt c base K a = [NH 3][H 3 O + ] [NH 4 + ] [H 3 O + ] = K a [NH 4 + ] [NH 3 ] ( NH + 4 (aq) + H 2 O(l) NH 3 (aq) + H 3 O + (aq)) ph = (p pk b ) log c salt c base = pk a log c salt c base 6
2 ph (a) [H 3 O + ], ph [NH 3 ] = c base = 0.1 mol dm 3, [NH 4 + ] = c salt = 0.1 mol dm 3 NH 4 + (aq) + H 2 O(l) NH 3 (aq) + H 3 O + (aq) K a = = [NH 3 ][H 3 O+ ] K b [NH + = 5.6 10 10 mol dm 3 4 ] [H 3 O + ] = K a [NH 4 + ] [NH 3 ] = K a = 5.6 10 10 mol dm 3, ph = 9.25 (b) 1 dm 3 1x10 4 mol NH 3 (aq) + HCl(aq) NH 4 + (aq) + Cl (aq) [NH 4 + ] = 0.1 + 0.0001 = 0.1001 mol dm 3 [NH 3 ] = 0.1 0.0001 = 0.0999 mol dm 3 11-13 [H 3 O + ] = (5.6 10 10 ) 0.1001 0.0999 = 5.61 10 10 mol dm 3, ph = 9.25 (c) 1 dm 3 1x10 4 mol NH 4 + (aq) + OH (aq) NH 3 (aq) + H 2 O(l) [NH 4 + ] = 0.1 0.0001 = 0.0999 mol dm 3 [NH 3 ] = 0.1 + 0.0001 = 0.1001 mol dm 3 11-14 [H 3 O + ] = (5.6 10 10 ) 0.0999 0.1001 = 5.59 10 10 mol dm 3, ph = 9.25 1 CH 3 COOH + CH 3 COONa 2 CH 3 COONa CH 3 COO (aq) + Na + (aq) CH 3 COOH(aq) + H 2 O(l) CH 3 COO (aq) + H 3 O + (aq) K a = [CH 3COO ][H 3 O + ], [CH 3 COOH] = c acid, [CH 3 COO ] = c salt [CH 3 COOH] [H 3 O + ] = K a [CH 3 COOH] [CH 3 COO ] = K a c acid c salt ph = pk a + log c salt c acid ( ) 12 7