Problem 12 - Chemistry: The Central Science

Question

Hydrogen sulfide is composed of two elements: hydrogen and sulfur. In an experiment, \(6.500 \mathrm{~g}\) of hydrogen sulfide is fully decomposed into its elements. (a) If \(0.384 \mathrm{~g}\) of hydrogen is obtained in this experiment, how many grams of sulfur must be obtained? (b) What fundamental law does this experiment demonstrate? (c) How is this law explained by Dalton's atomic theory?

Step-by-Step Solution

Answer

(a) To find the mass of sulfur obtained from the decomposition of \(6.500 \mathrm{~g}\) of hydrogen sulfide, given that \(0.384 \mathrm{~g}\) of hydrogen is obtained, subtract the mass of hydrogen from the mass of hydrogen sulfide: \(6.500 \mathrm{~g} - 0.384 \mathrm{~g} = 6.116 \mathrm{~g}\) of sulfur. (b) The fundamental law demonstrated in this experiment is the Law of Conservation of Mass, which states that the total mass of reactants should be equal to the total mass of products formed in a chemical reaction. (c) Dalton's atomic theory explains the Law of Conservation of Mass by stating that atoms are indivisible and indestructible particles that rearrange during chemical reactions. The total number of atoms in reactants must remain the same as the total number of atoms in the products, resulting in equal masses.

Step 1: Part (a): Calculate the mass of sulfur obtained

To calculate the mass of sulfur obtained from the decomposition of hydrogen sulfide, we need to use the conservation of mass principle. The total mass of hydrogen sulfide should be equal to the sum of the masses of hydrogen and sulfur formed upon decomposition. Mass of Hydrogen Sulfide = Mass of Hydrogen + Mass of Sulfur Given the mass of hydrogen sulfide (\(6.500 \mathrm{~g}\)) and the mass of hydrogen obtained (\(0.384 \mathrm{~g}\)), we can calculate the mass of sulfur: Mass of Sulfur = Mass of Hydrogen Sulfide - Mass of Hydrogen Mass of Sulfur = \(6.500 \mathrm{~g} - 0.384 \mathrm{~g}\) Mass of Sulfur = \(6.116 \mathrm{~g}\) Therefore, \(6.116 \mathrm{~g}\) of sulfur must be obtained.

Step 2: Part (b): Identify the fundamental law demonstrated by the experiment

The fundamental law demonstrated in this experiment is the Law of Conservation of Mass. This law states that the total mass of the reactants in a chemical reaction should be equal to the total mass of the products formed. In this case, the mass of hydrogen sulfide decomposed is equal to the sum of the masses of hydrogen and sulfur formed upon decomposition.

Step 3: Part (c): Explain the Law of Conservation of Mass using Dalton's atomic theory

Dalton's atomic theory can be used to explain the Law of Conservation of Mass. According to Dalton's atomic theory, all matter is composed of atoms, which are indivisible and indestructible particles. During a chemical reaction, atoms are rearranged to form new compounds, but the total number of atoms in the reactants must remain the same as the total number of atoms in the products. In the case of hydrogen sulfide decomposition, hydrogen and sulfur atoms are rearranged from the hydrogen sulfide molecule (H2S) to form separate hydrogen (H2) and sulfur (S) molecules. The number of hydrogen and sulfur atoms remains constant during this process, so the total mass of hydrogen and sulfur produced must be equal to the initial mass of hydrogen sulfide. This is consistent with the Law of Conservation of Mass.