Question

A chemist prepares a solution by adding 253 mg of Co(NO3)2 (MW = 182.94 g/mol ) to a volumetric flask, and then adding water until the total volume of the contents of the flask reaches the calibration line that indicates 100 mL . Determine the molarity of the prepared solution.

Answer 1

The molarity of the prepared solution : 0.014 M

Further explanation

Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

`\tt \large {\boxed {\bold {M ~ = ~ \frac {n} {V}}}`

Where

M = Molarity

n = number of moles of solute

V = Volume of solution

mass of solute (Co(NO₃)₂) :253 mg = 0.253 g

moles of solute (Co(NO₃)₂) :

`\tt mol=(mass)/(MW)\\\\mol=(0.253~g)/(182.94)\\\\mol=0.0014`

Volume of solution = 100 ml=0.1 L

The molarity :

`\tt molarity(M)=(0.0014)/(0.1)=0.014`