What is Stoichiometry?
Stoichiometry is the "recipe math" of chemistry. It tells you exactly how much of each ingredient (reactant) you need to make a specific amount of product.
Think of it like cooking!
If a recipe needs 2 eggs to make 12 cookies, how many eggs for 24 cookies? That's stoichiometry!
Understanding the Mole
What is a Mole?
A counting unit like "dozen" but for atoms. 1 mole = 6.022 × 10²³ particles
Molar Mass
The mass of 1 mole of a substance. Found on the periodic table (g/mol)
Avogadro's Number
6.022 × 10²³ - the number of particles in exactly 1 mole
4-Step Stoichiometry Process
Balance the Chemical Equation
Start with a balanced equation - this gives you the mole ratios!
Balanced: N₂ + 3H₂ → 2NH₃
Convert to Moles (if needed)
If given grams, convert to moles using molar mass.
Use Mole Ratios
Use coefficients from balanced equation to convert between substances.
Convert to Desired Units
Convert back to grams, molecules, or whatever the problem asks for.
Worked Example
Problem:
How many grams of NH₃ can be made from 14 grams of N₂?
Types of Stoichiometry Problems
Mole-to-Mole
Use coefficients directly from balanced equation.
Answer: 2 mol H₂O
Mass-to-Mass
Convert grams → moles → moles → grams.
Answer: 36 g H₂O
Limiting Reagent
Find which reactant runs out first.
Smallest ratio = limiting
Percent Yield
Compare actual vs theoretical yield.
Usually less than 100%
Ready to Practice Stoichiometry?
Use our tools to practice balancing equations and solving stoichiometry problems!