Solubility products and Carboxyl Groups

The solubility product of calcium sulfate is approximately as follows under the temperature conditions in question:

[Ca²⁺ ] x [SO₄^2- ] = 2.5 x 10^–5 (mole/liter)²

You also have been given the following data related to the concentrations of calcium and sulfate ions:

[Ca²⁺ ] = 1.5 mmole/L

[SO₄^2- ] = 3.8 mmole/L

1. What is the concentration of sulfate ions in moles per liter (show units!)?
2. What is the product of the calcium and sulfate ion concentrations?

Assume, for sake of simplicity, that all of the carboxyl groups at the fiber surface have the same equilibrium constant (which is true only as an approximation):

[RCOO^–]X[H⁺]/[RCOOH]=3.8 X 10^-5(moles/liter)

1. Based on the above equation, at what value of pH will one-half of the carboxyl groups be in their charged form?
2. If the pH is then raised to a higher value, will the fraction of dissociated carboxyl groups go up, down, or stay the same?