Question
Consider the following saturated solutions: CuSO4, BaSO4 , CaSO4 The order of cation concentration from highest to lowestis: A. [Ba2+] > [Ca2+] >[Cu2+] B. [Ca2+] > [Cu2+] >[Ba2+] C. [Cu2+] > [Ca2+] >[Ba2+] D. [Cu2+] > [Ba2+] >[Ca2+] The answer is C, but I don't know how to arrive to theanswer. Consider the following saturated solutions: CuSO4, BaSO4 , CaSO4 The order of cation concentration from highest to lowestis: A. [Ba2+] > [Ca2+] >[Cu2+] B. [Ca2+] > [Cu2+] >[Ba2+] C. [Cu2+] > [Ca2+] >[Ba2+] D. [Cu2+] > [Ba2+] >[Ca2+] The answer is C, but I don't know how to arrive to theanswer.
Explanation / Answer
The solubiliity rules for SO4 are as follows: Sulfate isusually soluble with most cations except when combined with Barium,Serenium, and Calcium. So based on this data it can be concludedthat Cu, copper is the most soluble and will dissociate the most.Therefore its concentration will be the highest. Thus thisinformation eliminates choices A and B. Now how to determine if Ba or Ca is more soluble Solbuilityand molecular weight can also be related. Barium weighs a lot morethan calcium. Barium is 137 grams/mol and Caclium is 40 grams/mol.Because barium weigs more than calcium, its solubility with thesolufate ion will b quite poor. Thereore the Calcium Sulfate willdissociate more than the BArium Sulfate, therefore the cocentrationof Ca+2 will be more than barium. Thus this eliminates choice D, sothe final answer is C Cu2+] > [Ca2+] >[Ba2+]