Question

Zinc, copper, lead, and mercury ions are toxic to Atlantic salmon at concentrations of 6.42 x 10^-2 mM, 7.16 x 10^-3 mM, 0.965 mM, and 5.00 x 10^-2 mM. What are the corresponding concentrations in milligrams per liter?

Answer 1

Concentrations

Zinc 6.42 x 10^-2 mM,

copper 7.16 x 10^-3 mM,

lead 0.965 mM,

mercury 5.00 x 10^-2 mM.

mM --> milimol --> mmol of X / per liter

note that if we use mmol, then we get miligrams

then,

change all moles of X to mass via

mass of X = mol of X * Molar mass of X

MW of Zn = 65.39

MW of Cu = 63.546

MW of Pb = 207.2

MW of Hg = 200.5900

now...

Zinc 6.42 x 10^-2 mM, --->

Zinc: mg per liter = (6.42*10^-2)*(65.39 ) =4.198 mg of Zn per liter

copper 7.16 x 10^-3 mM,

Copper : mg per liter = (7.16*10^-3)*(63.546 ) =0.4549 mg of Cu per liter

lead 0.965 mM,

Lead : mg per liter = (0.965)*(207.2 ) =199.948 mg of Pb per liter

mercury 5.00 x 10^-2 mM.

Hg : mg per liter = (5*10^-2)*(200.5900 ) =10.0295 mg of Hg per liter