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Zn Solubility

Zn Solubility. Zn2+ in ACSF . How much ZnCl2 can be added to a solution of ACSF at a given temperature before one will observe a precipitate. What effect does pH have on solutions. Formulas. Zinc Hydroxide in water. Zn(OH)2 (s)  Zn2+(aq) + 2OH- (aq) Ksp= 3.0x10-17

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Zn Solubility

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  1. Zn Solubility

  2. Zn2+ in ACSF • How much ZnCl2 can be added to a solution of ACSF at a given temperature before one will observe a precipitate. • What effect does pH have on solutions.

  3. Formulas • Zinc Hydroxide in water. • Zn(OH)2 (s)  Zn2+(aq) + 2OH- (aq) Ksp= 3.0x10-17 • 2OH-(aq)+ 2 H30+(aq) 4H20(l) (K1/w= 1.0x1014)2 • Zn(OH)2(s) + H30+ (aq) Zn2+ (aq) + 4H20(l) Knet= 3.0x10-17 * 1.0x1014 * 1.0x1014 = 3.0x1011

  4. pH determination • pH can be determined from the concentration of H30+ from the following equation: • pH=-log[H30+]

  5. From the reaction and the previous equation, the amount of Zn2+ in solution based on pH can be determined from the following equation: • 3.0x1011 = [Zn2+] _______ [H30+]2

  6. Or • 3.0x1011 * (10-pH)2 = [Zn2+] • Or • pH = -log ([Zn2+] / 3.0x1011)-1/2

  7. Some figured values are • pH 6: .3 M = [Zn2+] • pH 7: .003 = [Zn2+] • pH 8: 3.0x10-5 = [ Zn2+]

  8. Analyzing Solutions • pH= 7.29 • 24° C • 100 µM • 0/4 solutions had visible precipitations. • 200 µM • 0/4 solutions had visible precipitations. • 300 µM • 0/4 solutions had visible precipitations. • 400 µM • 0/4 solutions had visible precipitations. • 500 µM • 0/4 solutions had visible precipitations. • 600 µM • 0/4 solutions had visible precipitations. • Upon sitting, solutions that contained 400 µM to 600 µM ZnCl2 showed precipitation at the bottom of centrifuge tube. • pH of solution did not decrease significantly. Lowest pH was measured at 7.23

  9. pH= 7.19 • 21.6° C • 300 µM • 0/3 solutions had visible precipitations. • 400 µM • 0/3 solutions had visible precipitations. • 500 µM • 0/3 solutions had visible precipitations. • 600 µM • 0/3 solutions had visible precipitations. • Lowest pH was measured at 7.17

  10. At Higher Temperatures • pH= 7.29 • 34° C • 100 µM • 0/2 solutions had no visible ppt. • 200 µM • 0/2 solutions had no visible ppt. • 300 µM • 2/2 solutions had visible ppt. • 400 µM • 2/2 solutions had visible ppt. • 500 µM • 2/2 solutions had visible ppt. • 600 µM • 2/2 solutions had visible ppt. • All of these solutions had been left overnight in a water bath at 35° C.

  11. pH= 7.19 • 35.3° C • 300 µM • 0/3 solutions had visible ppt. • 400 µM • 0/3 solutions had visible ppt. • 500 µM • 0/3 solutions had visible ppt. • 600 µM • 0/3 solutions had visible ppt. • Solutions had been left standing for approximately 1 hour.

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