Calculate the mass fraction of potassium nitrate in the solution obtained by mixing 15 g of salt and 86 g of water.

Given:
m (KNO3) = 15 g
m (H2O) = 86 g

To find:
ω (KNO3) -?

1) Calculate the mass of the resulting potassium nitrate solution:
m solution (KNO3) = m (KNO3) + m (H2O) = 15 + 86 = 101 g;
2) Calculate the mass fraction of potassium nitrate in the resulting solution:
ω (KNO3) = m (KNO3) * 100% / m solution (KNO3) = 15 * 100% / 101 = 14.85%.

Answer: The mass fraction of potassium nitrate in the resulting solution is 14.85%.