The Calculation of Molarity in Household Ammonia Solution

Household ammonia, used as a window cleaner and for other cleaning purposes, is NH₃(aq). The NH₃ present in a 4.25-mL sample is neutralized by 37.74 mL of 1.048 M HCl(aq). The net ionic equation for the neutralization is NH₃(aq)+H⁺(aq)→NH⁺₄(aq). What is the molarity of NH₃ in the sample?

Final answer:

The molarity of the NH₃ solution is found by dividing the moles of NH₃, which is equivalent to the moles of HCl used in the neutralization, by the volume of the NH₃ solution. The molarity of the NH₃ solution is therefore 9.29 M.

Explanation:

The molarity of a solution is determined by dividing the number of moles of solute by the volume of the solution in liters. In this question, the NH₃ is neutralized by HCl. According to the balanced chemical equation, 1 mole of NH₃ reacts with 1 mole of H⁺ ions from HCl. Therefore, the number of moles of NH₃ is equal to the number of moles of HCl used:

Number of moles of HCl = Volume (L) x Molarity = 37.74 mL (0.03774 L) x 1.048 M = 0.0395 moles

The molarity of NH₃ can then be found using the formula:

Molarity of NH₃ = Moles of NH₃ / Volume of NH₃ solution in liters = 0.0395 moles / 0.00425 L = 9.29 M

What is the molarity of NH₃ in the sample?

The molarity of NH₃ in the sample is 9.29 M.