Stoichiometry Survival Guide Cheat Sheet
STOICHIOMETRY SURVIVAL GUIDE
The Ultimate Problem-Solving Cheat Sheet
Mass Conservation
"Matter cannot be created or destroyed in a chemical reaction."
Atoms: Reactant Count = Product Count
Mass: Total Reactant g = Total Product g
Moles: May vary between sides!
Molar Mass
The mass of 1 mole of a substance.
Unit: g/mol
Example: Fe(NO₃)₃
<table class="w-full text-xs"><tbody><tr class="border-b border-indigo-100 h-8"><td>Fe:</td><td class="text-right">1 × 55.8</td></tr><tr class="border-b border-indigo-100 h-8"><td>N:</td><td class="text-right">3 × 14.0</td></tr><tr class="border-b border-indigo-100 h-8"><td>O:</td><td class="text-right">9 × 16.0</td></tr><tr class="font-bold text-indigo-700 h-10 align-bottom"><td>Total:</td><td class="text-right">241.8 g/mol</td></tr></tbody></table>
Reaction Yield
Percent Yield Formula
\[ \frac{\text{Actual}}{\text{Theoretical}} \times 100 \]
Theoretical Yield The calculated maximum amount based on stoichiometry.
Actual Yield The real amount produced in the laboratory.
The Stoichiometry Road Map
Follow the path to convert from Substance A to Substance B
Mass of
Substance A (g)
/ Molar Mass
Moles of
Substance A
Mole Ratio
Moles of
Substance B
× Molar Mass
Mass of
Substance B (g)
Mole Ratio Secret
Look at the coefficients in the balanced equation. It's always "Unknown" over "Known".
Limiting Reactants
The ingredient that runs out first. It controls the maximum output. Calculate from moles!
5 Steps to Mastery
1
Balance the Chemical Equation
Correct coefficients are required for the mole ratio "bridge."
2
Convert Grams to Moles
Divide given mass by molar mass. Moles speak the universal language of reactions.
3
Apply the Mole Ratio
Multiply by \(\frac{\text{mol unknown}}{\text{mol known}}\) using balanced coefficients.
4
Convert Moles to Final Units
Multiply the resulting moles by molar mass to get back to grams (if asked).
5
Review Sig Figs & Units
Does the answer make sense? Check your rounding and labels.
Common Pitfalls
- Forgetting to distribute subscripts in molar mass.
- Inverting the mole ratio (Always: Want / Have).
- Not balancing the equation first.
Pro Tip
"Moles are the bridge. You cannot cross from mass of A to mass of B without stopping at the Mole Station first!"
Chemistry Unit: Stoichiometry
Unit 9 Reference Periodic Press © 2026
Stoichiometry Checkup Quiz
Stoichiometry Checkup
Cheat Sheet Mastery Assessment
Name:
Date:
Instructions: Use your Stoichiometry Survival Guide to answer the following questions. Choose the best answer for each question based on the concepts and formulas provided on the cheat sheet.
According to the Law of Conservation of Mass, which of the following quantities is NOT required to be the same on both the reactant and product sides of a chemical equation?
The total mass of all substances
The total number of individual atoms
The total number of moles of substances
The number of atoms of each specific element
Which unit is used to express the mass of one mole of a chemical substance?
mol/g
g/mol
grams
amu/mol
In the "Stoichiometry Road Map," what is the mandatory intermediate unit required to move from the mass of Substance A to the mass of Substance B?
The balanced coefficient bridge
Percent Yield
Moles
Theoretical mass
When calculating a mole ratio for the "bridge" step, where do the numbers for the ratio come from?
The subscripts in the chemical formulas
The coefficients of the balanced chemical equation
The molar masses from the periodic table
The actual yield measured in the lab
What is the "Theoretical Yield" of a chemical reaction?
The amount of product actually weighed in the lab
The percentage of the reaction that went to completion
The maximum amount of product that can be formed based on calculation
The mass of the reactant that is in excess
If a reaction has a percent yield of 100%, what does this mean?
The theoretical yield was greater than the actual yield
The actual yield was equal to the theoretical yield
No product was formed during the experiment
All reactants were converted into mass energy
Chemistry Mastery Series • Stoichiometry Quiz • Page 1 of 1
