Question

A chemist prepares a solution of sodium carbonate by measuring out of sodium carbonate into a volumetric flask and filling the flask to the mark with water. Calculate the concentration in of the chemist's sodium carbonate solution. Be sure your answer has the correct number of significant digits.

Answer 1

Answer:

The correct answer will be "$9.45\times 10^{-5} \ mol/L$".

Explanation:

We have:

Moles of solute (Na₂Co₃) = $18.9 \mu \ mol$

                                           = $18.9\times 10^{-6}$

                               $1 \mu \ mol$ = $10^{-6} \ mol$

Now,

The volume of the solution will be:

⇒  $0.200 \ L$

∴ ${1 \ mL=0.001 \ L}$

The formula to find the concentration will be:

⇒  $Concentration = \frac{moles \ of \ solute \ (mol)}{Volume \ of \ solution \ (L)}$

On substituting the given values, we get

⇒                          $=\frac{18.9\times 10^{-6}}{0.200}$

⇒                          $=9.45\times 10^{-5} \ mol/L$