Step 1 - Understanding % concentration in mass
% concentration in mass expresses the concentration of a solute by its percentage, in mass, in relation to the total mass of the solution.
Mathematically, we can find this percentage by the following relation:
[tex]\text{ \%concentration = }\frac{m_{solute}}{m_{solution}}\times100[/tex]Step 2 - Caculating the % concentration for the given solution
According to the exercise:
[tex]\begin{gathered} m_{solute}=3.5g\text{ \lparen NaCl is the solute\rparen} \\ \\ m_{solution}=100+3.5=103.5 \end{gathered}[/tex]Setting these values in the equation:
[tex]\text{ \%concentration = }\frac{3.5}{103.5}\times100=3.38\text{ \%}[/tex]Answer: the % concentration of NaCl in this solution is 3.38%.
