Question

A solution is obtained by mixing 300 g of {\text{25% }} solution and 400 g of {\text{40% }} solution by mass. Calculate the mass percentage of the resulting solution.

Answer 1

The mass percent of the solution gives the mass of solute present in ${\text{100 g}}$ of solution. The formula for the mass percent of the solution is as given below:

{\text{ }} \\\\$$ **Complete step by step answer:** The solution is obtained by mixing 300 g of $${\text{25% }}$$ solution and 400 g of $${\text{40% }}$$ solution by mass. Calculate the total mass of solution $${\text{Mass of solution = 300 g + 400 g}} \\\ {\text{Mass of solution}} = 700{\text{ g}} \\\ {\text{ }} \\\\$$ Calculate the mass of solute present in $${\text{300 g}}$$ of $${\text{25% }}$$ solution . $${\text{mass of solute = 300 g }} \times {\text{ }}\dfrac{{25}}{{100}} \\\ {\text{mass of solute = 75 g}} \\\\$$ Calculate the mass of solute present in $${\text{400 g}}$$ of $${\text{40% }}$$ solution . $${\text{mass of solute = 400 g }} \times {\text{ }}\dfrac{{40}}{{100}} \\\ {\text{mass of solute = 160 g}} \\\\$$ Calculate the total mass of solute $${\text{Total mass of solute = 75 g}} + {\text{160 g}} \\\ {\text{Total mass of solute = 235 g}} \\\\$$ Calculate the mass percentage of the resulting solution. $${\text{Mass percent = }}\dfrac{{{\text{Mass of solute}}}}{{{\text{Mass of solution}}}}{\text{ }} \times {\text{ 100 }} \\\ {\text{Mass percent = }}\dfrac{{{\text{235 g}}}}{{{\text{700 g}}}}{\text{ }} \times {\text{ 100 }} \\\ {\text{Mass percent = 33}}{\text{.6% }} \\\\$$ _**Hence, the mass percent of the resulting solution is $${\text{33}}{\text{.6% }}$$.**_ **Additional Information:** Another formula can be used to calculate the mass percent of the resulting solution. $${\text{Mass percent = }}\dfrac{{{\text{Mass of solute}}}}{{{\text{Mass of solute + Mass of solvent}}}}{\text{ }} \times {\text{ 100 }} \\\ {\text{ }} \\\ $$ Total mass of the solution is the sum of the masses of solute and solvent. **Note:** Similar to percentage by mass, another quantity frequently used is percentage by volume. It is the volume of solute present in $${\text{100 mL}}$$ of solution. The formula for the volume percent of the solution is as given below:

{\text{Volume percent = }}\dfrac{{{\text{Volume of solute }}\left( {{\text{mL}}} \right)}}{{{\text{Volume of solution }}\left( {{\text{mL}}} \right)}}{\text{ }} \times {\text{ 100 }} \\
{\text{ }} \\$$