According to the law of conservation of mass, if 29.5 grams of NH4Cl decomposes and 9.4 grams of NH3 is formed, how many grams of HCl must simultaneously be formed?

Question

The compound NH₄Cl can be decomposed to form NH₃ and HCl. This can be represented at the atomic level by a chemical equation:

1. NH₄Cl  NH₃ + HCl

According to the law of conservation of mass, if 29.5 grams of NH₄Cl decomposes and 9.4 grams of NH₃ is formed, how many grams of HCl must simultaneously be formed?

Answer 1

According to the law of conservation of mass, the mass of the starting material must be the same / equal to the mass of the final products. Thus, if you begin with 20.5 g of reactants (NH4Cl), the sum of the mass of the products must also be 20.5 g. Since one of the products has a mass of 9.4 g, the other must make up the difference.

NH₄Cl ==> NH₃ + HCl

20.5 g........9.4 g.....x g

Thus, you have 20.5 g - 9.4 g = 11.1 g = mass of HCl