Question

34.2g of glucose is dissolved in 400 g of water. Calculate percentage by mass of glucose solution.

Answer 1

Hint: The percentage by mass of a constituent is calculated by dividing the mass of the constituent by total mass of the solution and then multiplying it by 100. Calculate the total mass by adding the mass of glucose of water.

Complete step by step solution:We are given that $34.2{\text{ g}}$ of glucose is dissolved in $400{\text{ g}}$ of water.
Now, calculate the total mass of the glucose solution by adding the mass of glucose and water. Thus,
Total mass of the glucose solution $ = 32.4{\text{ g}} + {\text{400 g}}$
Total mass of the glucose solution $ = {\text{432}}{\text{.4 g}}$
Thus, the total mass of the glucose solution is ${\text{432}}{\text{.4 g}}$.
Now, calculate the percentage by mass of glucose by dividing the mass of glucose by the total mass and then multiplying by 100.
The formula for calculating the percentage by mass is as follows:
Percentage by mass $ = \dfrac{{{\text{Mass of solute (g)}}}}{{{\text{Mass of solute}} + {\text{Mass of solvent (g)}}}} \times 100$
Thus,
Percentage by mass of glucose $ = \dfrac{{34.2{\text{ g}}}}{{434.2{\text{ g}}}} \times 100$
Percentage by mass of glucose $ = 7.87\% $

Thus, the percentage by mass of glucose solution is $7.87\% $.

Note: The percentage by mass is a method of expressing the composition of the solution or mixture. The percentage by mass describes the amount of solute present in $100{\text{ g}}$ of the solution. You can also calculate the percentage by mass of an element in a compound using the same formula.