A solid laboratory unknown contains two substances, lead(II) carbonate and potassium carbonate. A 5.000 g sample of this unknown was treated with aqueous nitric acid to dissolve it, then, after further treatment to adjust the acidity, it was treated with an excess of potassium chromate solution. The precipitate which formed, when dried carefully and weighed, has a mass of 2.697 grams. Calculate the percent, by mass, of lead in this laboratory unknown. (hint: write a balanced equation, determine the formula of the ppt using solubility chart, then grams of lead using mole ratio.)
a. 34.60%
b. 50.00%
c. 65.91%
d. 72.93%
e. 77.38%