80 g of potassium chloride was dissolved in 420 g of water. Calculate the mass fraction of salt in the resulting solution.

1) Find the total mass of the resulting potassium chloride (KCl) solution:

mass of solution = mass of water + mass of potassium chloride = 420 + 80 = 500 (g).

2) Find the mass fraction of potassium chloride in the resulting solution.

Formula for finding the mass fraction:

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

Let’s substitute in this formula the values from the condition of the problem:

Mass fraction of KCl in solution = 80: 500 * 100% = 16%.

Answer: the mass fraction of potassium chloride (KCl), in the resulting solution, will be 16%.