Problem Analysis:
The task is to investigate and identify the
Law of Conservation of Mass in the context of chemical reactions. The Law of Conservation of Mass states that matter cannot be created or destroyed in an ordinary chemical reaction. This means that the total mass of reactants must equal the total mass of products.
To demonstrate this, all chemical equations must be balanced. Balancing a chemical equation involves adjusting the coefficients (numbers placed in front of chemical formulas) so that the number of atoms of each element is the same on both sides of the equation. Importantly,
subscripts in chemical formulas cannot be changed, as they define the composition of the molecules.
Example Provided:
The example given is:
\[
4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3
\]
#### Step-by-Step Explanation of the Example:
1.
Reactants:
- Iron (\(\text{Fe}\)): 4 atoms
- Oxygen (\(\text{O}_2\)): 3 molecules, which contain \(3 \times 2 = 6\) oxygen atoms
2.
Products:
- Ferric oxide (\(\text{Fe}_2\text{O}_3\)): 2 molecules
- Each molecule of \(\text{Fe}_2\text{O}_3\) contains 2 iron atoms and 3 oxygen atoms.
- Total iron atoms: \(2 \times 2 = 4\)
- Total oxygen atoms: \(2 \times 3 = 6\)
3.
Verification:
-
Iron (Fe):
- Reactants: 4 atoms
- Products: 4 atoms
- Balance: \(4 = 4\)
-
Oxygen (O):
- Reactants: 6 atoms
- Products: 6 atoms
- Balance: \(6 = 6\)
Since the number of atoms of each element is the same on both sides of the equation, the equation is balanced, and the Law of Conservation of Mass is satisfied.
General Steps for Balancing Chemical Equations:
1.
Write the Unbalanced Equation: Start with the chemical formulas of the reactants and products.
2.
Count the Atoms: Determine the number of atoms of each element on both sides of the equation.
3.
Balance the Elements: Adjust the coefficients in front of the chemical formulas to ensure the number of atoms of each element is the same on both sides. Start with elements that appear in only one reactant and one product, and work your way through the equation.
4.
Check Your Work: After balancing, recount the atoms of each element to ensure the equation is balanced.
5.
Do Not Change Subscripts: Remember that subscripts define the molecular formula and cannot be altered during balancing.
Conclusion:
The provided example demonstrates the Law of Conservation of Mass by showing that the balanced equation:
\[
4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3
\]
has an equal number of atoms of each element on both sides of the equation. This confirms that matter is conserved in the chemical reaction.
Thus, the solution is:
\[
\boxed{4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3}
\]
Parent Tip: Review the logic above to help your child master the concept of law of conservation of mass example problems.
