Question

What is the % concentration by mass of 3.5 g of NaCl dissolved in 100.0 grams of water

Answer 1

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:

`\text{ \%concentration = }(m_(solute))/(m_(solution))*100`

Step 2 - Caculating the % concentration for the given solution

According to the exercise:

`\begin{gathered} m_(solute)=3.5g\text{ \lparen NaCl is the solute\rparen} \\ \\ m_(solution)=100+3.5=103.5 \end{gathered}`

Setting these values in the equation:

`\text{ \%concentration = }(3.5)/(103.5)*100=3.38\text{ \%}`

Answer: the % concentration of NaCl in this solution is 3.38%.