Check my work please, not sure if this is right

[lan418]

The solubility of iron (II) hydroxide, Fe(OH)2, is 1.43E-3 grams per liter at 25 deg C.

a) Write the balanced equation for the solubility equilibrium.

My answer: Fe(OH)2 <----> Fe [2+] + 2 OH -

b)Write the expression for the solubility product constant, Ksp, and calculate its value.

My answer: 1.61 E - 14

c) Calculate the pH of the saturated solution of Fe(OH)2 at 25 deg C.

My answer: pH = 9.5

d) a 50.0 mL sample of 3.00 E -3 molar FeSO4 solution is added to a 50.0 mL of 4.00 E-6 molar NaOH solution. Does a precipitate of Fe(OH)2 form? explain and show calculations to support your answer.

 

i got to the point where no precipitate will form.

 

2. The acid ionization constant, Ka, for propanoic acid, C2H5COOH, is 1.3 E-5.

a) calculate the hydrogen ion concentration, [H+], in a .20-molar solution of propanoic acid.

My answer: [H+] = 1.6 E -3

b) Calculate the percentage of propanioc acid molecules that are ionized in the solution in a.

My answer: .8 %

c)what is the ratio of the concentration of the propanoate ion, C2H5COO- , to that of propanioc acid in a buffered solition with a pH of 5.20?

My answer: .49 for the ratio

d) In a 100 mL sample of a different buffer solution, the propanioc acid concentration is .50-molar and the sodium propanoate concentration is .50 molar. To this buffer solution, .0040 mole of solid NaOH is added. Calculate the pH of the resulting solution.

My answer: I am not very sure about this, i got final pH of 4.96