Calculate the mass fraction of the solution obtained by dissolving 15 g of salt in 100 g of water.

1) Find the mass of the resulting solution by the formula:

mass of solution = mass of solute + mass of solvent.

Let’s substitute the data from the problem statement into this formula:

solution mass = 15 g + 100 g = 115 (g).

2) Find the mass fraction of salt in the solution, according to the formula:

mass fraction of solute in solution = mass of substance: mass of solution * 100%.

Let’s substitute the initial data into this formula:

mass fraction of salt in solution = 15: 115 g * 100% = 13%.

That is, a 13% aqueous salt solution is obtained.