Question

As little as 1.oomg of Arsenic in 1-L of water can kill you. Calculate the following. Assume the density of the solution is 1.00g/cc.
a.) How many moles of arsenic in 1 mg?
b.) What is the mass percent of the solution?
c.) What is the concentration in ppm and ppb?
d.) What is the molarity of the solution?
Can anybody help me with this one please.

Answer 1

1 mg = 0.001 g. mols = grams/atomic mass As.

I assume this 1 mg As is in 1.00 L of solution but the problem doesn't say that
% by mass = (g As/1000g soln)*100 = ?

1 mg/L = 1 ppm = 1000 ppb

M = mols/L. You have mols from part a. That's in 1L soln. That's the M.