Question

Classify the following ionic compounds according to the Sigma-Aldrich solubility scale based on their molar solubility (S).

Answer choices are: Very Soluble, Freely Soluble, Soluble, Sparingly Soluble, Slightly Soluble, Very Slightly Soluble, and Practically Insoluble.

a) Silver nitrite (AgNO₂), S = 0.27 M. Answer is

b) Lithium Phosphate (Li₃PO₄), S = 3.4 x 10^-3 M. Answer is

c) Aluminum Fluoride (AlF₃), S = 8.6 x 10^-2 M. Answer is

d) Tin (II) Iodide (SnI₂), S = 2.9 x 10^-2 M. Answer is

Answer 1

(a): Silver nitrite (AgNO₂), molar mass, M = 153.87 g.mol-1

S = 0.27 M = 0.27 mol / L = 0.27 mol x153.87 g.mol-1 / L = 41.545 g / L = 41.545 g / 1000 mL

Hence volume of solvent required to dissolve 1 g AgNO2 = 1000 mL / 41.545 g = 24.07 mL / g

For a salt to be soluble, the range is 10 - 30 mL / g

Hence according to Sigma-Aldrich solubility, AgNO2 is Soluble (answer)

(b):  Lithium Phosphate (Li₃PO₄), molar mass, M = 115.794 g/mol

S = 3.4 x 10^-3 M = 3.4 x 10^-3 mol / L = 3.4 x 10^-3 mol x115.794 g.mol-1 / L = 0.3937 g / L = 0.3937 g / 1000 mL

Hence volume of solvent required to dissolve 1 g AgNO2 = 1000 mL / 0.3937 g = 2540 mL / g

For a salt to be Very Slightly Soluble, the range is 1000 - 10000 mL / g

Hence according to Sigma-Aldrich solubility, Li3PO4 is Very Slightly Soluble (answer)

(c): Aluminum Fluoride (AlF₃), molar mass = 83.977 g/mol

S = 8.6 x 10^-2 M = S = 8.6 x 10^-2 mol / L = S = 8.6 x 10^-2 mol x83.977 g.mol-1 / L = 7.222 g / L = 7.222 g / 1000 mL

Hence volume of solvent required to dissolve 1 g AlF3 = 1000 mL / 7.222 g = 138.5 mL / g

For a salt to be Slightly Soluble, the range is 100 - 1000 mL / g

Hence according to Sigma-Aldrich solubility, AlF3 is Slightly Soluble (answer)

(d): Tin (II) Iodide (SnI₂), molar mass = 372.52 g/mol

S = 2.9 x 10^-2 M = 2.9 x 10^-2 mol / L = 2.9 x 10^-2 mol x372.52 g.mol-1 / L = 10.80 g / L = 10.80 g / 1000 mL

Hence volume of solvent required to dissolve 1 g SnI2 = 1000 mL / 10.80 g = 92.6 mL / g

For a salt to be Sparingly Soluble, the range is 30 - 100 mL / g

Hence according to Sigma-Aldrich solubility, SnI2 is Sparingly Soluble (answer)