Question

Procaine hydrochloride ( = 272.77 g/mol) is used as a local anesthetic. Calculate the molarity of a 4.666 m solution which has a density of 1.1066 g/ml.

Answer 1

Answer : The molarity of solution will be, 2.27 mole/L

Explanation :

The relation between the molarity, molality and the density of the solution is,

$d=M[\frac{1}{m}+\frac{M_b}{1000}]$

where,

d = density of solution  = 1.1066 g/ml

m = molality of solution  = 4.666 m

M = molarity of solution  = ?

$M_b$ = molar mass of solute (Procaine hydrochloride) = 272.77 g/mole

Now put all the given values in the above formula, we get:

$1.1066=M[\frac{1}{4.66}+\frac{272.77}{1000}]$

$M=2.27mole/L$

Therefore, the molarity of solution will be, 2.27 mole/L

Answer 2

Procaine hydrochloride ( = 272.77 g/mol) is used as a local anesthetic. Calculate the molarity of a 4.666 m solution which has a density of 1.1066 g/ml.

molarity = Moles of solute /  volume of solution

          Molarity = m d / [ 1 + (mW / 1000)]

Molarity = 4.666 X 1.1066 / [ 1 + (4.666 X 272.77 / 1000)]

Molarity =  5.16 / 2.272= 2.271 M