Chemistry Regents: Stoichiometry Made Simple
Stoichiometry — the math of chemical reactions — is one of the most feared topics on the Chemistry Regents. But under the intimidating word is really just a step-by-step recipe. Once you learn the steps and practice them, these become guaranteed points instead of guesses.
Master the mole first
Everything in stoichiometry runs through the mole. Make sure you're rock-solid on converting between grams, moles, and particles using molar mass and Avogadro's number. If the mole concept is shaky, the rest will feel impossible — so nail this foundation first.
Balance the equation
Before any calculation, balance the chemical equation. The coefficients are the heart of stoichiometry — they tell you the ratio in which substances react. A common mistake is doing the math on an unbalanced equation, which throws off every answer that follows.
Use the mole ratio
The balanced coefficients give you the mole ratio between any two substances. To go from one substance to another, convert to moles, multiply by the mole ratio, then convert to whatever unit the question wants. It's the same three-step path every time: to moles, across the ratio, to your target.
Lean on the reference tables
The Chemistry Reference Tables give you key constants and information — use them. And watch your units and significant figures, since careless arithmetic costs points even when your method is right. Always glance at your answer to check it makes physical sense.
Practice the pattern
Stoichiometry rewards repetition. The more problems you work, the more the steps become automatic, until you can see the path the moment you read the question. Drill a variety of problem types so no version catches you off guard.
Regentify's Chemistry practice uses real past Regents questions with explanations, so you can drill stoichiometry until the recipe is second nature — and pick up the points that separate a pass from a great score. Free for every NY student.