A classic example of a chemical reaction is the combustion of methane, which can be represented by the following balanced chemical equation:
\[ \text{CH}_4(g) + 2\text{O}_2(g) \rightarrow \text{CO}_2(g) + 2\text{H}_2\text{O}(g) \]
Reactants:
- Methane (CH₄) - a hydrocarbon gas.
- Oxygen (O₂) - a diatomic molecule that is essential for combustion.
Products:
- Carbon Dioxide (CO₂) - a gas released into the atmosphere.
- Water (H₂O) - produced in the form of vapor.
Conservation of Matter:
In this reaction, the conservation of matter principle states that the total mass of the reactants must equal the total mass of the products. Let's examine how this is upheld in the methane combustion reaction:
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Counting Atoms: In the reactants, there is:
- 1 carbon atom (from CH₄)
- 4 hydrogen atoms (from CH₄)
- 4 oxygen atoms (from 2 O₂ molecules)
In the products, there is:
- 1 carbon atom (in CO₂)
- 4 hydrogen atoms (in 2 H₂O molecules)
- 4 oxygen atoms (2 from CO₂ and 2 from 2 H₂O)
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Mass Before and After: If we were to measure the mass of the reactants (1 molecule of CH₄ and 2 molecules of O₂) and compare it to the mass of the products (1 molecule of CO₂ and 2 molecules of H₂O), we would find that they are equal. In a closed system, none of the atoms are lost or gained; they are simply rearranged.
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Molecular Count Validation: The equation is balanced because:
- Carbon: 1 atom on each side.
- Hydrogen: 4 atoms on each side (4 H from CH₄ ---> 2 H₂O gives 4 H).
- Oxygen: 4 atoms on each side (2 O₂ provides 4 O ---> 1 CO₂ + 2 H₂O gives 4 O).
Thus, throughout the reaction, the total number of atoms remains constant, confirming that matter is conserved. This principle is a fundamental concept in chemistry, ensuring that when substances react chemically, their combined mass before and after the reaction remains unchanged.
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