Print version Updated: 31 March 2020 Lecture #37 Precipitation and - PowerPoint PPT Presentation

Print version Updated: 31 March 2020 Lecture #37 Precipitation and Dissolution: Metal Hydroxides/Oxides & Carbonates (Stumm & Morgan, Chapt.7) Benjamin; Chapter 8.7-8.15 David Reckhow CEE 680 #37 1

Practice Session  Al(OH) 3 ppt  Homework  Cr(OH) 3 ppt  Zn(OH) 2 ppt  Cd(OH) 2 ppt David Reckhow CEE 680 #37 2

Metal Precipitates; K so values (1/2)  Table 11.1a in Benjamin (pg 581) David Reckhow CEE 680 #37 3

Metal Precipitates; K so values (2/2)  Table 11.1b in Benjamin (pg 582) David Reckhow CEE 680 #37 4

Metal Hydrolysis  Table 10.2 in Benjamin  Pg 858-859 David Reckhow CEE 680 #37 5

Cd(OH) 2 example  Cd species equations  From Benjamin, pg 584 David Reckhow CEE 680 #37 6

Cd(OH) 2 solubility diagram  Pg 586 in Benjamin David Reckhow CEE 680 #37 7

Zinc with OH, CO 3 and Cl  Pg 636 in Benjamin David Reckhow CEE 680 #37 8

0 ZnOH + Zn +2 -1 Zn Total H + Zn(OH) 2 -2 -3 Zn(OH) 2 (aq) -4 Zn 2 (OH) +3 -5 Morgan’s fig. 6.8c, pg.273 -6 -2 Log C Zn(OH) 4  Compare to Stumm & -7 -2 Zn 2 (OH) 6 -8 -9 OH - - Zn(OH) 3  Zn solubility -10 -11 -12 -13 -14 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH David Reckhow CEE 680 #37 9

ZnO solubility Stumm & Morgan, 1996, Figure 7.6a, pg. 370 David Reckhow CEE 680 #37 10

ZnO solubility  With oxalate  10 -4 M Stumm & Morgan, 1996, Figure 7.6b, pg. 370 David Reckhow CEE 680 #37 11

0 -1 OH - H + -2 -3 -4 -5 -6 Fe Total Log C -7 - +4 Fe(OH) 4 Fe 2 (OH) 2 Fe +3 -8 -9 -10 FeOH +2 -11 + Fe(OH) 2 -12 -13 -14 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH David Reckhow CEE 680 #37 12

Fe with EDTA  10 -8 M EDTA  Elevates solubility in mid-pH range Stumm & Morgan, 1996, Figure 7.7a, pg. 371 David Reckhow CEE 680 #37 13

Fe with EDTA & Ca  10 -8 M EDTA  10 -2 M Ca  Mostly counteracts affect of EDTA Stumm & Morgan, 1996, Figure 7.7b, pg. 371 David Reckhow CEE 680 #37 14

 To next lecture David Reckhow CEE 680 #37 15