How many grams of water should be added to 80 g of a solution containing 15% salt to obtain a 12% solution?

Find the weight of the salt in the initial solution.

We multiply the mass of the solution by the percentage of salt concentration in it.

Will:

80 * 15% = 80 * 0.15 = 12 grams.

Let’s define a new mass of a 12% solution.

To do this, divide the found salt mass by the new concentration of the solution.

Will:

12/12% = 12 / 0.12 = 100 grams.

We find the mass of water to be added.

We subtract the initial (80 g) from the new mass of the solution (100 g).

100 – 80 = 20 grams.

Answer:

To obtain a 12% solution, you need to add 20 grams of water.