Question

1) Calcium chromate is a pigment for textiles and a corrosion inhibitor. Unfortunately, its dissolution reaction releases carcinogenic Cr6+ to the environment:

CaCrO₄(solid) yields Ca²⁺ (aq) + CrO₄^2- (aq)

The K_sp for calcium chromate is 1.7x10^-4 M² . At equilibrium, the activity of Ca²⁺ in solution is 0.027 M. What is the activity of CrO₄^2-?

2)

The value of log K_sp for calcium fluoride at 25^oC is -10.5.

The value of log K_sp for strontium fluoride at 25^oC is -8.4.

The value of log K_sp for barium fluoride at 25^oC is -6.0.

A) Which one is lease soluble?

B) What do you think is the reason for the trend in solubility of sulfate minerals as you go down the column of alkaline earth elements on the periodic table?

Answer 1