calculate the concentration of Ca2+ in a saturated solution of Ca(OH)2 (ksp= 0.0000055) with a pH of 12.55

A buffer solution consists of 0,25 mol∙dm–3 acetic acid (HC2H3O2; Ka= 1,8 x 10–5) and 0,35 mol∙dm–3 potassium acetate (KC2H3O2). Calculate the pH of the buffer solution. A small quantity (0,050 mol) of solid KOH is added to 1 dm3 of the buffer. This quantity is so small that it does not affect the volume of the buffer. Calculate the new pH of the buffer solution after the KOH has been added.

A chemistry graduate student is given 250. mL of a 1.00M propanoic acid (HC,H,CO₂) solution. Propanoic acid is a weak acid with K = 1.3 × 105. What mass of KC,H,CO2 should the student dissolve in the HC2H, CO2 solution to turn it into a buffer with pH = 4.33? You may assume that the volume of the solution doesn't change when the KC2H5CO2 is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits. x10

The Cr3+ concentration in a saturated solution of chromium(III) hydroxide is measured and found to be 1.28×10-8 M. Use this information to calculate a Ksp value for chromium(III) hydroxide.