TP sp for M 2 X 2 M X 2 is 8 10 11. Assume a maximum of moles of M 2 X can dissolve in one liter. What is true for? 1. sp 2 2. sp 2 2 3. sp 2 4. None of the above Lecture 22 CH102 A2 (MWF 11:1 am) Wednesday, March 21, 2018 Complete: Five kinds of solubility equilibria problems Practice with solubility equilibria Next lecture: Begin ch16: Electron transfer reactions and electrochemistry. For oxidation numbers and balancing redox equations, please work through http://goo.gl/mmeucs 1 2. From solubility get K sp Ch1: Solubility, precipitation, and complexation The solubility of magnesium phosphate is 0.00029 g/100 g of water at 20. Calculate its sp at this temperature. Mg 3 PO 4 2 3 Mg 2 2 PO 3 4 M 3 X 2 M 2 X 3 Initial excess 0 0 6 1
2. From solubility get K sp The solubility of magnesium phosphate is 0.00029 g/100 g of water at 20. Calculate its sp at this temperature. Mg 3 PO 4 2 3 Mg 2 2 PO 4 3 M 3 X 2 M 2 X 3 Initial excess 0 0 3 2 excess 3 2 0.00029 g/100 g mol/l sp M 2 3 X 3 2 3 3 2 2 108 Answer: 1.00 10 23 7 Calculate the molar solubility in a solution of 0.01 M NaF. 8 Calculate the molar solubility in a solution of 0.01 M NaF. Calculate the molar solubility in a solution of 0.01 M NaF. Initial Initial excess 0 c ion 9 10 2
Calculate the molar solubility in a solution of 0.01 M NaF. 4. Will precipitation occur? 0.2 mmol of NaF and 10 mmol of Ca NO 3 2 are combined in a total volume of 1 L of water. Will a precipitate form? The sp of CaF 2 is 3.9 10 11. Initial excess 0 c ion 2 excess c ion 2 c ion K sp M 2 X 2 c ion 2 Large c ion makes x smaller Answer: 1.7 10 7, 0.08 % of the value in pure water! Initial 11 12 4. Will precipitation occur? 0.2 mmol of NaF and 10 mmol of Ca NO 3 2 are combined in a total volume of 1 L of water. Will a precipitate form? The sp of CaF 2 is 3.9 10 11. When 0.2 mmol of NaF and 10 mmol of Ca NO 3 2 are combined in 1 L of water, sp of CaF 2 is 3.9 10 11. Initial 0 c M c X Is M 2 X 2 c M c X 2 sp sp? If no, then no precipitation. If yes, then a precipitate will form. Answer: sp 4 10 10 sp, so CaF 2 will precipitate 13 14 3
When 0.2 mmol of NaF and 10 mmol of Ca NO 3 2 are combined in 1 L of water, Initial mol Revised M Initial mol 0 0.0100 mol 0.0002 mol Revised M 1 16 Initial mol 0 0.0100 mol 0.0002 mol Revised M 0.0001 mol 0.0099 mol/v 0 Initial 0 0.0100 mol 0.0002 mol Revised 0.0001 mol 0.0099 mol/v 0/V 2 17 18 4
Initial 0 0.0100 mol 0.0002 mol Revised 0.0001 mol 0.0099 mol/v 0/V 2 0.0001 mol 0.0099 mol/v 2 Initial 0 0.0100 mol 0.0002 mol Revised 0.0001 mol 0.0099 mol/v 0/V 2 0.0001 mol 0.0099 mol/v 2 19 K sp M 2 X 2 0.0099 2 y 2 Answer: Ca 2 0.0099 M, F 2 y 0.000063 M Check: Q sp 0.0099 0.000063 2 3.9 10 11 K sp 20 Practice with solubility equilibria TP The expression for the equilibrium constant for the solubility equilibrium M 2 X 2 M X 2 is 1. sp 2 M X 2 / M 2 X 2. sp 2 M 2 X 2 / M 2 X 3. sp 2 M 2 X 2 4. sp M 2 X 2 21 22
TP sp for M 2 X 2 M X 2 is 8 10 11. Assume a maximum of moles of M 2 X can dissolve in one liter. What is true for? 1. sp 2 2. sp 2 2 3. sp 2 4. None of the above Quiz sp for M 2 X 2 M X 2 is 8 10 11. Assume a maximum of y moles of M 2 X can dissolve in one liter. What is true for if M is initially 0.1 M that is, M is a common ion? 1. sp 2 0.1 2. sp 2 0.1 2 3. sp 0.1 2 4. sp 0.1. None of the above 23 24 6