Question

if you have a saline solution which is 2.000# mass, and its density is 1.011 g/ml, what is the molarity of Na+ in the solution?

Answer 1

Solution :-

Given data

mass percent of the saline solution = 2.00 %

density = 1.011 g / ml

lets assume we have 100 ml of solution

then mass of solution = volume * density

                                = 100 ml * 1.011 g per ml

                                = 101.1 g

now lets calculate the mass of the NaCl using the mass percent

mass of NaCl = 101.1 g * 2.00 % /100 % = 2.022 g

now lets calculate the moles of the NaCl

moles of NaCl = mass / molar mass

                     = 2.022 g / 58.443 g per mol

                     = 0.0346 mol NaCl

mole ratio of the NaCl to Na^+ is 1 :1 therefore moles of the Na^+ = 0.0346 mol

now lets calculate the molarity of the Na^+

molarity = moles / volume in liter

molarity of the Na^+ = 0.0346 mol / 0.100 L

                             = 0.346 M

therefore the molarity of the Na^+ in the salide solution = 0.346 M