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Chemistry: Chemical Reactions & Stoichiometry Flashcards

7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which type of reaction is 2H2O2 -> 2H2O + O2?

    Answer: Decomposition

    One compound breaks down into two simpler products, defining decomposition.

  2. In a limiting reactant problem, 3 mol H2 react with 2 mol N2 to form NH3 (N2 + 3H2 -> 2NH3). Which is limiting?

    Answer: H2

    3 mol H2 only needs 1 mol N2, but each requires 3 mol H2 per N2; H2 runs out first making it limiting.

  3. What is the empirical formula of a compound that is 40.0% C, 6.7% H, and 53.3% O by mass?

    Answer: CH2O

    Moles give a 1:2:1 C:H:O ratio, so the empirical formula is CH2O.

  4. How many grams are in 0.250 mol of NaCl (molar mass 58.44 g/mol)?

    Answer: 14.6 g

    0.250 mol x 58.44 g/mol = 14.6 g.

  5. Which is the correctly balanced equation for the combustion of methane?

    Answer: CH4 + 2O2 -> CO2 + 2H2O

    CH4 + 2O2 -> CO2 + 2H2O balances all C, H, and O atoms.

  6. At STP, what volume does 2.00 mol of an ideal gas occupy?

    Answer: 44.8 L

    Each mole occupies 22.4 L at STP, so 2.00 mol is 44.8 L.

  7. What is the oxidation number of sulfur in SO4^2-?

    Answer: +6

    Four oxygens at -2 total -8; the ion is -2, so sulfur must be +6.