Notes on Balancing Chemical Equations
Definition of a Balanced Equation
- A balanced equation has the same number of each type of atom on both sides of the equation.
- This means that the mass and charge are conserved in a chemical reaction.
Balancing Chemical Equations
- To balance a chemical equation, you must ensure that the number of reactant atoms equals the number of product atoms.
- You can adjust coefficients, but not subscripts, to achieve balance.
Example of Balancing
- Review the original equation given:
- Unbalanced Equation: aA + bB \rightarrow cC + dD
- Balance by adjusting coefficients (a, b, c, d) without changing the subscripts of compounds.
Reactants and Products
- Reactants: The starting substances in a chemical reaction.
- Products: The substances formed as a result of the chemical reaction.
- Example: In the reaction C6H{12}O6 + 6O2 \rightarrow 6CO2 + 6H2O
- Reactants: Glucose (C6H{12}O6) and oxygen (O2)
- Products: Carbon dioxide (CO2) and water (H2O)
Importance of Subscripts
- Subscripts: Represent the number of atoms in a molecule.
- Example: In H_2O, the subscript 2 indicates there are two hydrogen atoms for every one oxygen atom.
- Changing subscripts alters the substance completely and is NOT allowed in balancing equations.
- You can only change coefficients to balance equations, maintaining the integrity of the chemical identities.
Drawing Molecular Structures
- To visualize molecules when balancing, draw them out:
- Carbon (C)
- 3 Carbon atoms: C_3
- Water molecules represented as 3 H_2O
- Result of the reaction should also show as: 2H_2O.
Checking Balance
- After balancing, always check that both sides of the equation reflect the same number of each atom.
- For instance, in the equation:
- Original reaction: C6H{12}O6 + 6O2 \rightarrow 6CO2 + 6H2O
- Check:
- Left: 6 Carbon, 12 Hydrogen, 12 Oxygen
- Right: 6 Carbon, 12 Oxygen + 6 Hydrogen from 6H_2O = 12 Hydrogen
- Thus, it is balanced after confirming that all elements are equal on both sides.
