Answer to Question #298081 in Chemistry for Dave

Question

find the number of millimoles of solute in:

a. 2.00 L of 2.76 x 10-3 M KMnO4

b. 250 mL of a solution that contains 4.20 ppm of CuSO4

Answer 1

a) C_M = n / V

n = C_M x V = 2.76 x 10^-3 x 2.00 = 5.52 x 10^-3 mol = 5.52 mmol

b) ppm = mg/L

m (CuSO₄) = 4.20 x 0.25 = 1.05 mg = 0.00105 g

n = m / M

M (CuSO₄) = 159.6 g/mol

n (CuSO₄) = 0.00105 / 159.6 = 0.00000658 mol = 0.00000000658 mmol