Stoichiometry
Why must a chemical equation be balanced before using mole ratios?
The coefficients in the balanced equation provide the mole relationship between reactants and products.
AP Chemistry
AP Chemistry 2026 practice predictions
For AP Chemistry 2026, prioritize mole ratios, equilibrium versus rate, particle-level explanations, data representation and claim-evidence argumentation.
Structure signal
What this page is based on
AP Chemistry has 60 multiple-choice questions in 90 minutes and 7 free-response questions in 105 minutes: 3 long-answer and 4 short-answer questions.
AP Chemistry Exam - AP CentralFocus areas
High-value practice angles for 2026
- Stoichiometry
- Equilibrium
- Kinetics
- Thermodynamics
- Particle models
- Experimental error
Original practice
Sample prompts
Equilibrium versus rate
A catalyst is added to a reaction at equilibrium. What changes and what does not?
The forward and reverse rates both increase, but the equilibrium position and equilibrium constant do not change.
Argumentation
A student claims a reaction is endothermic because the solution gets colder. What evidence should support that claim?
They should link the temperature decrease to energy absorbed from the surroundings and use the sign of enthalpy where data is provided.