Question

A chemist prepares a solution by adding 448 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 500 mL . Determine the molarity of the prepared solution.

Answer 1

Answer:

Molarity of solution is 0.0049 M

Explanation:

Molarity of a solution is the ratio of number of moles of solute to volume of solution in Liter

Number of moles is the ratio of mass to molecular weight of a compound.

Here $Co(NO_{3})_{2}$ is the solute.

448 mg of $Co(NO_{3})_{2}$ = 0.448 g of $Co(NO_{3})_{2}$

So, 0.448 g of $Co(NO_{3})_{2}$ = $\frac{0.448}{182.94}$ moles of $Co(NO_{3})_{2}$ = 0.00245 moles of $Co(NO_{3})_{2}$

Total volume of solution = 500 mL = 0.5 L

So, molarity of solution  = $\frac{0.00245}{0.5}M=0.0049 M$