To prepare a 20% solution of sucrose, you need to calculate the mass of water required to dissolve 750 g of sucrose.
A 20% solution means that 20 g of sucrose is dissolved in every 100 g of the solution. Therefore, you'll have 20 g of sucrose in every 100 g of the final solution.
Let's assume the mass of water needed is "W" grams.
The total mass of the solution will be the sum of the mass of sucrose and the mass of water:
Total mass of solution = mass of sucrose + mass of water
We know that the mass of sucrose is 750 g, and we want 20% of the solution to be sucrose. So, we can set up the following equation:
20% of total mass = mass of sucrose
(20/100) * (mass of sucrose + mass of water) = mass of sucrose
(20/100) * (750 g + W g) = 750 g
Simplifying the equation:
(20/100) * (750 g + W g) = 750 g
(20/100) * (750 g) + (20/100) * (W g) = 750 g
150 g + (20/100) * W g = 750 g
(20/100) * W g = 750 g - 150 g
(20/100) * W g = 600 g
Simplifying further:
0.2W g = 600 g
W g = 600 g / 0.2
W g = 3000 g
Therefore, you need to add 3000 grams (3 kg) of water to prepare a 20% solution of sucrose from 750 g of sucrose.