Question

If the density of ocean water at depth of 10,000m is 1.071g/ml and if 25.0g of water at that depth contains 190mg of KCl what is the molarity of KCL?

Answer 1

mols KCl = grams/molar mass = approx 0.0025 mols KCl in 25.0 g H2O at that depth but that's an estimate.
How much volume is the 25.0g?
That's mass = volume x density and v = m/d = 25.0/1.071 = ? and convert to L.
Then = M = mols/L

Answer 2

1.07e-4