Problem 12 - Chemistry The Central Science

Question

Hydrogen sulfide is composed of two elements: hydrogen and sulfur. In an experiment, 6.500 g of hydrogen sulfide is fully decomposed into its elements. (a) If 0.384 g of hydrogen is obtained in this experiment, how many grams of sulfur must be obtained? (b) What fundamental law does this experiment demonstrate?

Step-by-Step Solution

Answer

(a) To calculate the mass of sulfur, subtract the mass of hydrogen (0.384 g) from the mass of hydrogen sulfide (6.500 g). Mass of sulfur = 6.500 g - 0.384 g = 6.116 g. Thus, 6.116 grams of sulfur must be obtained in this experiment. (b) This experiment demonstrates the fundamental law of conservation of mass, which states that the mass of the reactants in a chemical reaction is equal to the mass of the products. In this case, hydrogen sulfide decomposed into hydrogen and sulfur, with the total mass remaining constant.

Step 1: Identify the given values

The given values are: - Mass of hydrogen sulfide: 6.500 g - Mass of hydrogen: 0.384 g

Step 2: Calculate the mass of sulfur

To calculate the mass of sulfur, we will subtract the mass of hydrogen from the mass of hydrogen sulfide: Mass of sulfur = Mass of hydrogen sulfide - Mass of hydrogen Plug in the given values: Mass of sulfur = 6.500 g - 0.384 g

Step 3: Calculate the answer

After performing the subtraction, we find the mass of sulfur: Mass of sulfur = 6.116 g Therefore, 6.116 grams of sulfur must be obtained in this experiment. #part (b):#

Step 4: Identify the fundamental law

The experiment demonstrates the fundamental law of conservation of mass. This law states that in a chemical reaction, the mass of the reactants (the initial substances) is equal to the mass of the products (the substances formed). In this case, the hydrogen sulfide decomposed into hydrogen and sulfur, and the total mass remained constant.

Key Concepts

Chemical Decomposition

Chemical decomposition, also known as chemical breakdown or analysis, is a process where a complex substance breaks down into two or more simpler substances. It's a kind of chemical reaction that is often represented by a general equation:
\[ AB \rightarrow A + B \]
For instance, hydrogen sulfide (H_2S) decomposing into hydrogen (H_2) and sulfur (S) is an example of such a reaction. When you observe the decomposition of hydrogen sulfide as in the exercise, the mass of hydrogen and sulfur obtained showcases the breakdown of the original compound. Each component retains its unique properties, demonstrating that no new elements are created or destroyed in this process but are simply reorganized into different forms.

Stoichiometry

Stoichiometry is the section of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It relies on the conservation of mass, with the principle assuming that matter is neither created nor destroyed during a chemical reaction.
When applying stoichiometry to the decomposition of hydrogen sulfide, we work out how many grams of each element are present before and after the reaction. The initial mass of hydrogen sulfide (6.500 g) and the known mass of one of the elements after decomposition (0.384 g of hydrogen) allows us to calculate the mass of the other element (sulfur), ensuring the mass is conserved. This is a typical stoichiometric calculation, linking the mass of reactants to the mass of products.

Chemical Reaction

A chemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, known as products. Chemical reactions can vary greatly in terms of the types of substances involved and the changes they undergo.
In our case, the decomposition of hydrogen sulfide is a type of chemical reaction where the only reactant undergoes a breakdown to yield simpler products - hydrogen and sulfur. Understanding chemical reactions requires comprehension of how molecules interact, bond structures, and the conservation of mass and energy. Comprehending these changes is crucial for predicting reaction outcomes, balancing equations, and practical applications like the creation of new materials or pharmaceuticals.

Elemental Composition

Elemental composition refers to the identity and quantity of the elements that make up a chemical compound. Knowing the elemental composition is fundamental in understanding a substance's properties and behavior in reactions.
For instance, hydrogen sulfide is composed of hydrogen and sulfur in a fixed ratio. When it decomposes, the mass of each element is conserved, which is consistent with the known elemental composition of the compound. By analyzing the mass of each element present in the resultant substances, we gain insight into the original elemental proportion within the compound. This concept is crucial for tasks such as determining the formula of an unknown compound or verifying the purity of a substance.