if there are 8.0 mg of Na+ contaminant per liter of water sample, calculate the number of moles of Na+ per liter. Calculate the weight of Na+ in a 1L sample of water that contains 1.00 x 10^2 umol Na+/L

Answer 1

8.0 mg = 0.0080 g and
moles = grams/molar mass.
0.0080 g/23 = moles and that is moles/L of soln.
A sample that is 100 umol Na/L = 0.100 mol/L so in 1 L you will have 0.100 moles Na^+. Then moles = grams/molar mass. You know moles and molar mass, solve for grams.

Answer 2

if there are 8.0 mg of Na+ contaminant per liter of water sample, calculate the number of moles of Na+ per liter. Calculate the weight of Na+ in a 1L sample of water that contains 1.00 x 10^2 umol Na+/L