15 g of NH3 was dissolved in 100 g of water. determine the mass fraction of the substance in the solution.

1) Find the total mass of the resulting ammonia solution (NH3):

mass of solution = 100 g of water + 15 g of ammonia = 115 g.

2) We will use the formula to find the mass fraction of a solute in a solution:

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

Let’s substitute the data into this formula, from the condition of the problem:

mass fraction of ammonia (NH3) in solution = mass of ammonia: total mass of solution * 100% = 15: 115 * 100% = 13%.

Answer: the mass fraction of ammonia (NH3) in this aqueous solution will be 13%.