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# Chemistry: molar solubility, hydroxide concentrations, ph level

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The Ksp of La(IO3)3 is 1.0×10-11. Using activities, what is the molar solubility of La(IO3)3 in a 0.050 M solution of NaNO3?

Using activities, calculate the hydroxide concentration in a saturated solution of iron (II) hydroxide in 0.010 M magnesium nitrate. The Ksp for Fe(OH)2 is 7.9×10-16, assume that Mg(NO3)2 dissociates completely

What is the pH of a 3.6×10-8 M solution of HNO3.

https://brainmass.com/chemistry/physical-chemistry/chemistry-molar-solubility-hydroxide-concentrations-ph-level-283735

#### Solution Preview

The Ksp of La(IO3)3 is 1.0×10-11. Using activities, what is the molar solubility of La(IO3)3 in a 0.050 M solution of NaNO3?

The dissociation equation for La(IO3)3 is:

La(IO3)3  La3+ + 3IO3-
Initial concn ------- 0 0
Change s 3s
Equilibrium concn s 3s

Note = s is the concentration of saturated solution, hence the molar solubility

Ksp = a La3+(a IO3-)3 where a = activity =  [X]

 = activity coefficient

[X] = concentration of species

Ksp =  La3+[ La3+]( IO3-[ IO3-])3
Ksp =  La3+ (s) (IO3-)3 (3s)3
Ksp = 1 x 10-11 = 27s4 (La3+) (IO3-)3

To solve for activity coefficient ():

• calculate ionic strength (µ)
µ = ½  miZi2

NaNO3  Na+ + NO3-
0.05 M 0.05 0.05

µ = ½ [(0.05)(1)2 + ...

#### Solution Summary

Molar solubility, hydroxide concentrations and ph levels in chemistry are examined. The activities are given.

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