An organic base (B) has a pKa of 6.950 and a distribution constant (KD), between water and ether, of 3.0. The organic base is extracted from 225 mL of a 0.175 M aqueous solution of B, that has been adjusted to a pH of 8.00, with 75.5 mL of ether. Only one extraction is performed. Calculate the concentration of the organic base (B) in the water phase after the extraction.

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)