Question

How many grams of cobalt (II) nitrate, Co(NO3)2, are required to make a 2.20%(w/v) aqueous solution in a 250 mL volumetric flask?

Answer 1

Answer:

$\large \boxed{\text{5.50 g}}$

Explanation:

Percent means " per hundred," so % m/V means the grams of something in 100 mL of  volume.

$\text{m/V \%} = \dfrac{\text{mass of solute} }{\text{volume of solution}} \times 100 \, \%$

Data:

         m/V % = 2.20 %

V of solution = 250 mL

Calculations:

$\text{2.20 \%} = \dfrac{\text{mass of solute} }{\text{250 mL}} \times 100 \, \%\\\\\text{Mass of solute} = \dfrac{2.20\, \% \times \text{250 mL}}{100 \%} = \text{5.50 g}\\\\\text{The mass of Co(NO _{3} ) _{2} is \large \boxed{\textbf{5.50 g}} }$