Zn Solubility

Zn2+ in ACSFHow 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.

FormulasZinc Hydroxide in water.Zn(OH)2 (s) Zn2+(aq) + 2OH- (aq) Ksp= 3.0x10-172OH-(aq)+ 2 H30+(aq) 4H20(l) (K1/w= 1.0x1014)2Zn(OH)2(s) + H30+ (aq) Zn2+ (aq) + 4H20(l) Knet= 3.0x10-17 * 1.0x1014 * 1.0x1014 = 3.0x1011

pH determinationpH can be determined from the concentration of H30+ from the following equation:

pH=-log[H30+]

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

Or3.0x1011 * (10-pH)2 = [Zn2+]

Or

pH = -log ([Zn2+] / 3.0x1011)-1/2

Some figured values are

pH 6: .3 M = [Zn2+]pH 7: .003 = [Zn2+]pH 8: 3.0x10-5 = [ Zn2+]

Analyzing SolutionspH= 7.2924 C100 M0/4 solutions had visible precipitations.200 M0/4 solutions had visible precipitations.300 M0/4 solutions had visible precipitations.400 M0/4 solutions had visible precipitations.500 M0/4 solutions had visible precipitations.600 M0/4 solutions had visible precipitations.Upon sitting, solutions that contained 400 M to 600 M ZnCl2 showed precipitation at the bottom of centrifuge tube.pH of solution did not decrease significantly. Lowest pH was measured at 7.23

pH= 7.1921.6 C300 M0/3 solutions had visible precipitations.400 M0/3 solutions had visible precipitations.500 M0/3 solutions had visible precipitations.600 M0/3 solutions had visible precipitations.Lowest pH was measured at 7.17

At Higher TemperaturespH= 7.2934 C100 M0/2 solutions had no visible ppt.200 M0/2 solutions had no visible ppt.300 M2/2 solutions had visible ppt.400 M2/2 solutions had visible ppt.500 M2/2 solutions had visible ppt.600 M2/2 solutions had visible ppt.All of these solutions had been left overnight in a water bath at 35 C.

pH= 7.1935.3 C300 M0/3 solutions had visible ppt.400 M0/3 solutions had visible ppt.500 M0/3 solutions had visible ppt.600 M0/3 solutions had visible ppt.Solutions had been left standing for approximately 1 hour.