Stoichiometry, solved with a reliable route every time
Every stoichiometry problem follows the same path: grams → moles → ratio → moles → grams. Noeta makes that route automatic.
What this covers
- Balancing equations
- Mole ratios from coefficients
- Limiting and excess reagents
- Percentage yield
- Solution and gas stoichiometry
Worked example
Problem
How many grams of H₂O form from 4 g of H₂ reacting with excess O₂?
- 1Balance2H₂ + O₂ → 2H₂O.
- 2Convert to moles4 g ÷ 2 g/mol = 2 mol H₂.
- 3Apply the ratio2:2 means 2 mol H₂O.
- 4Convert back2 mol × 18 g/mol.
Answer: 36 g of water
Mistakes that cost marks
- Using an unbalanced equation for the mole ratio.
- Assuming the smaller mass is the limiting reagent instead of comparing moles.
- Rounding molar masses too early.
Questions students ask
How do I find the limiting reagent?
Divide each reactant's moles by its coefficient; the smallest result limits the reaction.
Practise quantitative chemistry until it sticks
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