How many grams of glucose (C6H12O6) need to be added to 765.0 mL of water to form a 20.0% solution?

Question

matt101 · Answer

When we talk about a 20% solution, where the solute is a solid (as it is here), the % is referring to % of mass of the solution. The % won't refer to volume here, because we assume the solid contributes negligibly to the volume of the solution after dissolving in the water. The density of water is 1 g/mL, so 765 mL of water has a mass of 765 g. What mass of glucose should be added so that 20% of the total mass is glucose?

$$\frac{x}{x+765}=0.2$$
Solve for x and you have your answer! If you have any questions let me know!