Chemical Reactions Quiz
Questions: 16 · 10 minutes
1. For the equilibrium N₂ + 3H₂ ⇌ 2NH₃, what happens when additional H₂ is introduced while other conditions remain constant?
The equilibrium shifts left to form more H₂
The reaction stops because the mixture is no longer balanced
The equilibrium constant becomes zero
The equilibrium shifts right to form more NH₃
2. Hydrogen and oxygen react according to 2H₂ + O₂ → 2H₂O. If 4 moles of H₂ are mixed with 1 mole of O₂, which substance is the limiting reactant?
O₂
H₂
H₂O
Neither reactant; they are present in exact proportions
3. Which pair of aqueous solutions is expected to produce an insoluble precipitate when mixed?
Ethanol and water
Hydrochloric acid and sodium hydroxide
Sodium nitrate and potassium chloride
Silver nitrate and sodium chloride
4. Two clear aqueous solutions are mixed at room temperature. Which observation most directly indicates that a chemical reaction has formed a new substance?
The liquids become evenly mixed
The combined liquid occupies a larger volume
An insoluble solid appears in the mixture
The container feels wet on the outside
5. In AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq), which ions are spectators?
Ag⁺ and Cl⁻
Ag⁺ and NO₃⁻
Na⁺ and NO₃⁻
Na⁺ and Cl⁻
6. An energy diagram shows the products at a lower energy level than the reactants. What does this indicate?
The reaction releases net energy to the surroundings
The reaction has no activation-energy barrier
The products must react immediately to reform the reactants
The reaction cannot occur without continuous heating
7. Which products are formed in the neutralization reaction HCl + NaOH → ?
NaCl and H₂O
NaOH₂ and Cl
Na and HClO
NaCl and H₂
8. Powdered calcium carbonate reacts with acid faster than the same mass of calcium carbonate chips under identical conditions. Why?
The powder contains more calcium carbonate particles by mass
The powder exposes a greater surface area for collisions
The powder lowers the acid's concentration
The chips have a lower chemical potential because they are larger
9. Which set of coefficients correctly balances Fe + O₂ → Fe₂O₃?
2, 1, 1
4, 3, 2
2, 3, 1
3, 2, 1
10. Which classification best describes Zn + CuSO₄ → ZnSO₄ + Cu?
Acid-base neutralization
Redox reaction
Decomposition without electron transfer
Precipitation caused by two soluble salts
11. What does a catalyst do in a chemical reaction?
It increases the amount of product allowed by equilibrium
It provides an alternative pathway with lower activation energy
It raises the activation energy of the reaction
It supplies atoms that become part of every product molecule
12. Magnesium ribbon burns in oxygen and produces only magnesium oxide. How is this reaction best classified from its pattern of reactants and products?
Synthesis, because multiple reactants combine to form one compound
Decomposition, because energy is involved in breaking down magnesium
Single displacement, because magnesium replaces oxygen
Double displacement, because the reactants exchange ions
13. Methane burns with a limited oxygen supply. Compared with complete combustion, which carbon-containing product is more likely to form?
Calcium carbonate
Methanol
Carbonic acid
Carbon monoxide
14. When calcium carbonate is heated, it forms calcium oxide and carbon dioxide. Which description best fits this change?
Combustion, because heat is supplied to the reactant
Neutralization, because the products include an oxide
Synthesis, because the atoms remain conserved
Decomposition, because one compound forms two simpler substances
15. A gas produced when an acid reacts with a carbonate turns limewater cloudy. Which gas was produced?
Hydrogen
Oxygen
Carbon dioxide
Chlorine
16. A student reacts an acid with a carbonate in an uncovered flask. The measured mass decreases during the reaction. What is the best explanation?
The reaction destroyed part of the carbonate's mass
Some matter was converted completely into energy
Carbon dioxide formed and escaped from the flask
The balance cannot measure substances after they react