Question

Isotonic saline solution has a mass % nacl concentration of 0.900 %. assuming its density is 1.00 g/ml, what is its molarity

a. 9.00 x 10-3 m
b. 0.0900 m
c. 0.154 m
d. 0.900 m
e. 1.80 m

Answer 1

In this item, we calculate the moles of NaCl with the basis of 1L of solution.
First, calculate the mass of the solution using the density.
m = (1L) x (1000g/1000mL)(1000mL/1L) = 1000g
Then, we calculate mass of NaCl by multiplying the calculate value with the percentage.
m of NaCl = (1000 g)(0.0090) = 9 g
Then, calculate the moles of NaCl by the molar mass.
molarity = (9g)(1 mole/ 58.44 g) = 0.1539 mole / L solution or 0.1529M. Then, the answer to this item is letter C.