Problem 37 - Chemistry Matter and Change

Question

Conservation of Mass Explain how Dalton's atomic theory offered a convincing explanation of the observation that mass is conserved in chemical reactions.

Step-by-Step Solution

Answer

Dalton's atomic theory explained that atoms rearrange in reactions without being created or destroyed, thus conserving mass.

Step 1: Understanding Dalton's Atomic Theory

John Dalton's atomic theory proposed that matter is composed of small, indivisible particles called atoms. According to this theory, these atoms cannot be created or destroyed; they can only be rearranged during chemical reactions. This foundational idea set the stage for explaining how mass is conserved.

Step 2: Describing Chemical Reactions with Atoms

In a chemical reaction, Dalton's theory suggests that the atoms of the reactants rearrange to form products, essentially shuffling the same atoms into new configurations. Because the total number and types of atoms remain unchanged during the reaction, the mass likewise remains constant.

Step 3: Conservation of Mass Explained

Since atoms themselves are neither created nor destroyed in reactions, the mass of the system remains the same before and after the reaction. This supports the law of conservation of mass, as the total mass of the reactants equals the total mass of the products.

Key Concepts

Dalton's Atomic Theory

Dalton's Atomic Theory was a groundbreaking idea that changed the way we understand chemistry. John Dalton suggested that everything in the universe is made up of tiny particles called atoms. These atoms are the fundamental building blocks and they are indivisible, meaning they cannot be split into smaller parts. This theory was important because it explained that during any chemical process or reaction, the atoms involved only rearrange themselves, but do not change their identity or mass. Therefore, Dalton's theory established the groundwork for understanding why mass is conserved during chemical reactions.

Chemical Reactions

Chemical reactions are processes where substances, called reactants, convert to different substances, known as products. According to Dalton's theory, during a chemical reaction, atoms are neither created nor destroyed; rather, they just change partners. This rearrangement of atoms leads to the formation of new compounds. For example, when hydrogen and oxygen react, they form water. The atoms of hydrogen and oxygen simply join in a new arrangement to form the molecule of water. Since the total number and type of atoms remain the same, the overall mass does not change. This reaffirms the longstanding idea of the conservation of mass.

Atoms

Atoms are the smallest units that retain all the properties of an element. Each atom consists of a nucleus, containing protons and neutrons, and electrons that circle around the nucleus. Despite their small size, atoms are incredibly influential in understanding chemical reactions. Every element on the periodic table consists of only one type of atom. These atoms can connect with each other through chemical bonds, granting them the ability to form compounds. Atoms are the main characters in the story of chemistry, acting as unchanging entities that rearrange during chemical reactions without altering their mass. Dalton's Atomic Theory gave us this vital insight into the role atoms play in every chemical transformation.

Law of Conservation of Mass

The Law of Conservation of Mass states that in a closed system, the mass remains constant, regardless of the processes acting inside the system. This foundational principle of chemistry tells us that mass cannot be created or destroyed within an isolated system, such as a sealed chemical reaction vessel. This law was clarified through Dalton's Atomic Theory, which demonstrated that because atoms are neither created nor destroyed during chemical reactions, the total mass of the system's reactants must equal that of the products. Understanding this law helps scientists accurately predict the outcomes of chemical reactions and ensures that chemical equations are balanced, demonstrating conservation of mass.