AP Chemistry · Summary

Unit 4 summary

1. Balance with coefficients only, then check that atoms and charge match on both sides.
2. A net ionic equation keeps only the species that change; compounds of Na⁺, K⁺, NH₄⁺ and NO₃⁻ are always soluble, so those ions are spectators in precipitation.
3. Proton transfer means acid-base; a change in oxidation number means redox, and electrons lost must equal electrons gained.
4. Stoichiometry runs grams → moles → mole ratio → moles → grams; molarity × liters also gives moles.
5. Find the limiting reactant through the mole ratio, not by comparing masses, and compute every product from it.
6. Percent yield is actual ÷ theoretical × 100; a wet or impure product raises it, and lost product lowers it.
7. In a titration, moles of titrant at the equivalence point fix the moles of sample through the mole ratio; use M₁V₁ = M₂V₂ only for a 1 : 1 reaction.