To count the number of particles on each side of a chemical reaction, you follow these steps:
Counting Particles in a Chemical Reaction
- Identify the particles to count : Particles can be atoms or molecules depending on what you want to analyze.
- Atom count involves counting individual atoms of each element on both sides.
- Molecule count involves counting whole molecules or compounds as particles
- Write down the chemical equation with reactants on the left and products on the right.
- Break down molecules into atoms (for atom counting):
- Split each molecule into its constituent atoms.
- Multiply the subscript numbers by the coefficient in front of the molecule to get the total atoms of each element
- Count the total number of each particle on both sides :
- For atoms, sum the atoms of each element on the reactant side and compare to the product side.
- For molecules, count how many molecules of each compound appear on each side, considering coefficients
- Compare the counts on both sides :
- The Law of Conservation of Mass states the number of atoms of each element must be the same on both sides.
- If counts differ, adjust coefficients to balance the equation
Example
For a reaction like 4P4+5O2→2P4O10\text{4P}_4+5\text{O}_2\to 2\text{P}4\text{O}{10}4P4+5O2→2P4O10:
- Count atoms on reactant side:
- P: 4×4=164\times 4=164×4=16 atoms
- O: 5×2=105\times 2=105×2=10 atoms
- Count atoms on product side:
- P: 2×4=82\times 4=82×4=8 atoms
- O: 2×10=202\times 10=202×10=20 atoms
- Since counts differ, the equation is unbalanced and coefficients need adjustment
Summary
- Use coefficients and subscripts to multiply and count total atoms or molecules.
- List each element separately and tally atoms on both sides.
- Adjust coefficients to ensure equal particle counts on both sides, respecting conservation laws
This method provides a systematic way to count and compare particles in chemical reactions.
