Question

A clinical serum sample is determined to have an inorganic phosphate concentration of 9.3 mg/dL, which is outside the normal range of 3.0 to 4.5 mg/dL for adults. Calculate the molar concentration of phosphate in this serum sample. Please show your work.

Answer 1

9.3 mg / dL

1 dL = 0.1 L

1mg = 10^-3 g

9.3 mg / dL = 9.3 x 10^-3 g / 0.1 L

                   = 9.3 x 10^-2 g /L

molar mass of phosphate (PO4-3) = 95 g/mol

molarity = g/L / molar mass

              = 9.3 x 10^-2 (g /L ) / 95 (g /mol)

             = 9.789 x 10^-4 mol / L

             = 9.8 x 10^-4 M

molar concentration = 9.8 x 10^-4 M