SAT Subject Test in Chemistry

The SAT Subject Test in Chemistry assesses students' understanding of chemical concepts and their ability to apply them in problem-solving.

Atomic StructureChemical BondingStates of Matter & Gas Laws
Chemical EquilibriumAcids, Bases, and pHStoichiometry
Chemistry in MedicineEnvironmental ChemistryHousehold Chemistry
Time Management on the TestSmart Guessing and Elimination
Atomic StructureChemical BondingStates of Matter & G...Chemical EquilibriumAcids, Bases, and pHStoichiometryChemistry in Medicin...Environmental Chemis...Household ChemistryTime Management on t...Smart Guessing and E...
Advanced Topics

Stoichiometry

Counting Atoms in Reactions

Stoichiometry is the math of chemistry—it uses balanced equations to calculate the amounts of reactants and products in a reaction.

The Mole Concept

  • 1 mole = \( 6.02 \times 10^{23} \) particles (Avogadro's number)
  • Moles convert between atomic scale and grams

Solving Problems

Steps:

  1. Balance the chemical equation
  2. Convert grams to moles
  3. Use mole ratios from the equation
  4. Convert back to grams if needed

Why It Matters

Whether baking cookies or making medicine, stoichiometry ensures the right proportions for a successful outcome.

Key Formula

\[n = \frac{m}{M}\]

Examples

  • If you start with 10 g of hydrogen and excess oxygen, you can calculate the grams of water produced.

  • In the reaction \( 2H_2 + O_2 \to 2H_2O \), 4 moles of hydrogen make 4 moles of water.

In a Nutshell

Stoichiometry uses balanced equations and the mole concept to calculate quantities in chemical reactions.

Key Terms

Mole
A unit representing \( 6.02 \times 10^{23} \) entities (atoms, molecules, etc.).
Molar Mass
The mass of one mole of a substance.
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Chemistry in Medicine