Reaction Types
Identify the type of reaction: NaOH + HCl → NaCl + H₂O
Neutralization (Double Replacement)
Balance: ___Al + ___O₂ → ___Al₂O₃
4Al + 3O₂ → 2Al₂O₃
2H₂ + O₂ → 2H₂O. How many grams H₂O from 4 g H₂?
4 g H₂ × (1 mol/2.02 g) × (2 mol H₂O / 2 mol H₂) × (18.02 g/mol) = 35.6 g H₂O
Define limiting reactant.
The reactant that is completely consumed and limits product formation.
NaCl + AgNO₃ → ? Net ionic?
Ag⁺ + Cl⁻ → AgCl(s)
What type of reaction produces a gas, water, and salt from an acid and carbonate?
Acid-carbonate reaction (double replacement + decomposition)
Balance: ___C₂H₆ + ___O₂ → ___CO₂ + ___H₂O
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
Define mole ratio.
The ratio of moles of reactants/products from a balanced equation used to convert between substances.
5.0 g Mg & 5.0 g HCl. Limiting? (Mg + 2HCl → MgCl₂ + H₂)
Convert both to moles H₂. HCl is limiting.
Spectator ions in: Ba(NO₃)₂ + Na₂SO₄ → BaSO₄ + NaNO₃
Na⁺ and NO₃⁻
Is this redox reaction a single replacement or synthesis? Zn + CuSO₄ → ZnSO₄ + Cu
Single replacement
Why can polyatomic ions be balanced as units?
Because they remain unchanged during reaction if present on both sides (e.g., SO₄²⁻).
10.0 g Ca + H₂O. How many L of H₂ at STP?
10.0 g Ca × (1 mol / 40.08 g) × (1 mol H₂ / 1 mol Ca) × 22.4 L/mol = ~5.6 L H₂
What happens to excess reactants?
Remain unreacted; can be recovered or reused.
Why does sugar not appear in ionic equations?
Covalent compound; doesn’t dissociate in solution.
Explain why combustion reactions always release energy. Include a general chemical form.
Combustion is exothermic because CₓHᵧ + O₂ → CO₂ + H₂O releases energy as bonds form in stable CO₂ and H₂O.
Real-world unbalanced: Fe + O₂ → Fe₂O₃. Balance it.
4Fe + 3O₂ → 2Fe₂O₃
Actual: 15.0 g; theoretical: 20.0 g. % yield?
(15.0 / 20.0) × 100 = 75%
Design lab to determine limiting reactant.
Mix known volumes/molarities, filter for precipitate, compare expected vs actual mass.
Write a gas-forming reaction’s net ionic. Example: Na₂CO₃ + HCl →
CO₃²⁻ + 2H⁺ → CO₂(g) + H₂O
Describe the driving forces behind double replacement reactions and when no reaction occurs.
Driving forces: formation of precipitate, gas, or water. No reaction occurs if all products remain aqueous.
Balance in acid: MnO₄⁻ + Fe²⁺ → Mn²⁺ + Fe³⁺
MnO₄⁻ + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O
88 g CO₂ (44 g/mol), 54 g H₂O (18 g/mol). Empirical formula?
**Moles C = 88/44 = 2; Moles H = (54/18) × 2 = 6 → Empirical formula: CH₃
(NH₄)₂SO₄ + BaCl₂ → BaSO₄(s). Given 0.1 M of each, equal volume, which is limiting?
Equal moles; limiting depends on volume used. If equal volume, no limiting unless one is slightly less concentrated.
(NH₄)₂CO₃ + Pb(NO₃)₂ → precipitate? Net ionic?
Yes, PbCO₃(s) forms. Net ionic: Pb²⁺ + CO₃²⁻ → PbCO₃(s)