Copper is known to be toxic to fish, and in particular, the $C{u}^{2+}$ species shows greatest

toxicity.

a$.$ Calculate the speciation of $Cu($II$)$ for freshwater at a $pH$ value of $8\mathrm{.}3$ as the hardness

increases from $20($soft$)$ to $100($moderately hard$)$ to $200($very hard$)m\frac{g}{L}$ as

$CaC{O}_3.$ Assume that the total divalent $Cu(II)$ concentration is $10\frac{g}{L}.$

b$.$ Based on your findings in part $($a$),$ do you think it is appropriate to set a single

regulatory limit or should it depend on variables such as $pH$ and hardness? Explain

your answer.