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Tuesday, September 23, 2014

Solubility Product Constant Problems, 2

Category: Chemical Engineering Math

"Published in Newark, California, USA"

The pH of a saturated solution of Fe(OH)2 is 9.30. Calculate the Ksp of Fe(OH)2.

Solution:

If the pH of Fe(OH)2 is 9.30, then the pOH is 





The concentration of hydroxide ion in molarity is




Take the inverse logarithm on both sides of the equation, we have




Since Fe(OH)2 is slightly soluble in water, then the ionization of Fe(OH)2 is 


By using mole to mole relationship of the reactants and products in a liter of solution, if


then it follows that


 

Therefore, the solubility product constant of Fe(OH)2 is