Section 8.5: Clcultions Involving Bsic Solutions Tutoril 1 Prctice, pge 527 1. Given: [OH (q)] 0.000 mol/l Required: [H + (q)], [OH (q)] [OH (q)] 0.000 mol/l ecuse OH is strong se. + 1.0 [H ] [OH ( q )] + 1.0 Solution: [H ] 0.000 [H + (q)] 1.00 11 mol/l [OH (q)] 1.00 mol/l 2. Given: [Sr(OH) 2 (q)] 0.042 mol/2.00l 0.021 mol/l [OH (q)] 0.042 mol/l ecuse Sr(OH) 2 is strong se producing 2 mol OH per mole of compound Solution: poh log[oh (q)] log(0.042) 1.688 poh 1.77 ph 14.00 poh ph 12.64 Tutoril 2 Prctice, pge 529 1. () From tle, (C 2 H O 2 ) 5.6 () From tle, (H BO ) 5.8 w 1.0 5.8 1.7 5 2. Given: [se] 0.20 mol/l;.82 se(q) #!!! "! se + (q) + OH (q) I 0.20 0 0 C x + x + x E 0.20 x x x + [se (q)][oh (q)] [se(q)] Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-1
Solution: ( x)( x).82 (0.20 x) ()() x x.82 0.20 x 2 7.64 9 x [OH (q)] 8.74 5 mol/l poh log(8.74 5 ) poh 4.06 ph 14.00 4.06 ph 8.94. Given: [N 2 H 4 ] 4.5 mol/l; 1.7 6 N 2 H 4 (q) + H 2 O(l) #!!! "! N 2 H + 5 (q) + OH (q) I 4.5 0 0 C x + x + x E 4.5 x x x [N2H5 [N2H4 q ] 6 ( x)( x) Solution: 1.7 (4.5 x) 6 ( x)( x) 1.7 4.5 x 2 7.65 6 x [OH (q)] 2.77 mol/l poh log(2.77 ) poh 2.56 ph 14.00 2.56 ph 11.44 Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-2
Section 8.5 Questions, pge 50 1. () Given: [NOH (q)] 0.0000 mol/l [OH (q)] 0.0000 mol/l ecuse OH is strong se. Solution: poh log[oh (q)] log(0.0000) 2.52 ph 14.000 poh 14.000 2.52 ph 11.477 () Given: [B(OH) 2 (q)] 0.0020 mol/l [OH (q)] 0.0040 mol/l ecuse B(OH) 2 is strong se producing 2 mol OH per mole of compound Solution: poh log[oh (q)] log(0.0040) 2.40 poh 2.40 ph 14.00 poh ph 11.60 (c) Given: [CH NH 2 (q)] 0.0 mol/l; 9.6 4 CH NH 2 (q) #!!! "! CH NH + (q) + OH (q) I 0.0 0 0 C x + x + x E 0.0 x x x [CHNH [CHNH 2 q ] 4 ( x)( x) Solution: 9.6 (0.0 x) 4 ( x)( x) 9.6 0.0 x 2 9.6 6 x [OH (q)]. mol/l poh log(. ) poh 2.51 ph 14.00 2.51 ph 11.49 Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-
(d) Given: [N 2 H 4 ] 0.0250 mol/l; 1.7 6 N 2 H 4 (q) + H 2 O(l) #!!! "! N 2 H + 5 (q) + OH (q) I 0.0250 0 0 C x + x + x E 0.0250 x x x [N2H5 [N2H4 q ] 6 ( x)( x) Solution: 1.7 (0.0250 x) 6 ()() x x 1.7 0.0250 x 2 4.25 8 x [OH (q)] 2.06 4 mol/l poh log(2.06 4 ) poh.69 ph 14.00.69 ph.1 2. () From tle, (H 2 S) 1.1 7 w 1.0 7 1.1 9.1 8 () 7.2 4 w 1.0 4 7.2 1.4 11 (c) From tle, (HCN) 6.2 w 1.0 6.2 1.6 5 Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-4
(d) From tle, (HF) 6.6 4 w 1.0 4 6.6 1.5 11. () Given: [C 17 H 19 NO (q)] 0.01 mol/l; 7.5 7 C 17 H 19 NO (q) + H 2 O(l) #!!! "! C 17 H 20 NO + (q) + OH (q) I 0.01 0 0 C x + x + x E 0.01 x x x [C17H20NO [C17H19NO q ] 7 ( x)( x) Solution: 7.5 (0.01 x) 7 ( x)( x) 7.5 0.01 x 2 7.5 9 x [OH (q)] 8.7 5 mol/l poh log(8.7 5 ) poh 4.06 ph 14.00 4.06 ph 9.94 () Given: [C 21 H 22 N 2 O 2 (q)] 0.001 mol/l; 1.0 6 C 21 H 22 N 2 O 2 (q) + H 2 O(l) #!!! "! C 21 H 2 N 2 O + 2 (q) + OH (q) I 0.001 0 0 C x + x + x E 0.001 x x x 21 22 2 2 [C21H2N2O2 [C H N O q ] Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-5
Solution: 6 ()() x x 1.0 (0.001 x) 6 ( x)( x) 1.0 0.001 x 2 1.0 9 x [OH (q)].2 5 mol/l poh log(.2 5 ) poh 4.50 ph 14.00 4.50 ph 9.50 4. () Given: ([C 2 H 5 ) N(q)] 0.20 mol/l; 4.0 4 Required: [H + (q)], [OH (q)], ph (C 2 H 5 ) N(q) + H 2 O(l) #!!! "! (C 2 H 5 ) NH + (q) + OH (q) I 0.20 0 0 C x + x + x E 0.20 x x x ( 2 5) [CH [ C H NH N q] Solution: 2 5 4 ()() x x 4.0 (0.20 x) 4 ( x)( x) 4.0 0.20 x 2 8.00 5 x [OH (q)] 8.94 mol/l [H + (q)] [OH (q)] 1.0 + 1.0 [H (q)] 8.94 [H + (q)] 1.12 11 mol/l ph log(1.12 11 ) 11.95 Sttement: [OH (q)] 8.9 mol/l; [H + (q)] 1.1 11 mol/l; ph 11.95 Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-6
() Given: [HONH 2 (q)] 0.20 mol/l; 1.1 8 Required: [H + (q)], [OH (q)], ph HONH 2 (q) #!!! "! NH + 2 (q) + OH (q) I 0.20 0 0 C x + x + x E 0.20 x x x [NH2 [HONH2 ( q )] 8 ()() x x Solution: 1.1 (0.20 x) 8 ( x)( x) 1.1 0.20 x 2 2.2 9 x [OH (q)] 4.7 5 mol/l [H + (q)] [OH (q)] 1.0 + 1.0 [H (q)] 5 4.7 [H + (q)] 2.1 mol/l ph log(2.1 ) 9.67 Sttement: [OH (q)] 4.7 5 mol/l; [H + (q)] 2.1 mol/l; ph 9.7 5. Given: [C(OH) 2 ] 0.00040 mol/l; 5.0 11 Required: [OH (q)], poh, ph Solution: [OH (q)] 0.00080 mol/l ecuse C(OH) 2 is strong se. poh log(0.00080). ph 14.00. ph.90 Sttement: [OH (q)] 0.00080 mol/l; poh.; ph.90 Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-7
6. () Given: [OH] 25 g/l Required: [OH (q)], poh, ph 25 g 1 mol Solution: 0.45 mol/l L 56.0 g [OH (q)] 0.45 mol/l ecuse OH is strong se. poh log(0.45) 0.5 ph 14.00 0.5 ph 1.65 Sttement: [OH (q)] 0.45 mol/l; poh 0.5; ph 1.65 () Given: [NOH] 150.0 g/l Required: [OH (q)], poh, ph 150.0 g 1 mol Solution:.75 mol/l L 40.00 g [OH (q)].75 mol/l ecuse NOH is strong se. poh log(.75) 0.57 ph 14.00 (0.57) ph 14.57 Sttement: [OH (q)].75 mol/l; poh 0.57; ph 14.57 7. Given: ph 11.80; 1.8 5 Required: [NH (q)] NH (q) + H 2 O(l) NH + 4 (q) + OH (q) Solution: poh 14.00 11.80 2.20 [OH (q)] 2.20 [OH (q)] 6. mol/l [NH4 ( q )][OH (q)] [NH q ] 1.8 5 (6. )(6. ) [NH q ] (6. )(6. ) 5 [NH q ] 1.8 [NH ] 2.2 mol/l 8. Answers will vry. Smple nswer: Use chemicl sfety goggles nd/or full fce shield where splshing is possile. Wer protective clothing, including gloves, l cot, or pron. Work in fume hood. Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-8
9. () () (c) 2 + ( q )][H (q)] 2 2 [HCO2H [HCO q ] [HCO2 [HCO H q ] + [HCO H [HCO2 q ][H (q)] [HCO q ] [HCO H q ] + [OH (q)] [H (q)] w 2 1 1. () Given: ph 11.2; 4.4 4 Required: [CH NH 2 (q)] CH NH 2 (q) + H 2 O(l) CH NH + (q) + OH (q) Solution: poh 14.00 11.20 2.80 [OH (q)] 2.80 [OH (q)] 1.6 mol/l 4.4 [NH 4 [NH q ] 4 (1.6 )(1.6 ) 2 [CH NH q ] (1.6 )(1.6 ) 2 4 [CH NH q ] 4.4 [CH NH 2 ] 0.0058 mol/l; this is not the correct concentrtion. () The solution is too dilute. (c) Answers my vry. Smple nswer: A Cost Gurd cocktil is comintion of drugs, including ephedrine tht is used to prevent sesickness. The ephedrine prevents the drowsiness tht is side effect of the other drug. It is not now generlly used ecuse ephedrine cn cuse nuse, insomni, confusion, nd occsionlly hypertension. 2 Copyright 2012 Nelson Eduction Ltd. Chpter 8: Acid-Bse Equilirium 8.5-9