CHEM103 Final Assessment Review –
Questions & Answers Graded A+
Q1. What is the difference between an alkane and an alkene?
. Alkanes contain only single bonds (saturated hydrocarbons), while alkenes contain at
least one double bond (unsaturated hydrocarbons).
Q2. What physical properties are commonly used to distinguish alkanes from alkenes in
the lab?
. Boiling point, density, and chemical reactivity (alkenes decolorize bromine water due to
double bonds).
Thermochemistry
Q3. Calculate ΔH for the combustion of methane (CH₄) using bond enthalpies.
. ΔH ≈ –890 kJ/mol (exothermic reaction).
Q4. State Hess’s Law.
. The enthalpy change of a reaction is the same regardless of the pathway taken, as
long as initial and final states are the same.
Equilibrium
Q5. For the reaction N₂ + 3H₂ ⇌ 2NH₃, what happens if pressure is increased?
. Equilibrium shifts to the right (towards fewer gas molecules).
Q6. What is the equilibrium constant expression for the reaction:
2SO₂ + O₂ ⇌ 2SO₃ ?
. K=\frac{[SO_3]^2}{[SO_2]^2[O_2]}
Electrochemistry
Q7. In a galvanic cell, which electrode is the anode?
. The electrode where oxidation occurs.
Q8. What is the standard reduction potential of a hydrogen electrode?
0.00 V (defined reference).
Kinetics
Q9. How does a catalyst affect a chemical reaction?
It lowers the activation energy, increasing the reaction rate without being consumed.
Q10. What is the rate law for a reaction?
An equation that relates the reaction rate to the concentration of reactants, e.g., Rate =
k[A]^m[B]^n.
Q11. What happens to the freezing point of a solution when solute is added?
, The freezing point decreases (freezing point depression).
Q12. Define molarity.
. Molarity (M) = moles of solute ÷ liters of solution.
Atomic Structure & Bonding
Q13. What is the electron configuration of oxygen?
. 1s² 2s² 2p⁴
Q14. Define electronegativity.
A14. The tendency of an atom to attract electrons in a chemical bond.
Q15. Which bond is more polar: C–H or O–H?
. O–H, because oxygen is more electronegative than carbon.
States of Matter
Q16. What is the ideal gas law?
. PV=nRT
Q17. At constant temperature, what happens to pressure if volume decreases?
A17. Pressure increases (Boyle’s Law).
Q18. Define molar volume at STP.
. 22.4 L per mole of gas.
Thermochemistry
Q19. What is specific heat capacity?
. The amount of heat required to raise 1 g of a substance by 1°C.
Q20. Endothermic vs. exothermic reaction?
. Endothermic absorbs heat; exothermic releases heat.
Q21. What is ΔH for a reaction at constant pressure?
. The heat exchanged with surroundings.
Equilibrium
Q22. What does Le Châtelier’s Principle state?
. A system at equilibrium shifts to counteract changes in conditions.
Q23. If temperature increases in an exothermic reaction, which way does equilibrium
shift?
. To the left (reactants).
Q24. What does a large K value indicate?
. Products are favored at equilibrium.
Questions & Answers Graded A+
Q1. What is the difference between an alkane and an alkene?
. Alkanes contain only single bonds (saturated hydrocarbons), while alkenes contain at
least one double bond (unsaturated hydrocarbons).
Q2. What physical properties are commonly used to distinguish alkanes from alkenes in
the lab?
. Boiling point, density, and chemical reactivity (alkenes decolorize bromine water due to
double bonds).
Thermochemistry
Q3. Calculate ΔH for the combustion of methane (CH₄) using bond enthalpies.
. ΔH ≈ –890 kJ/mol (exothermic reaction).
Q4. State Hess’s Law.
. The enthalpy change of a reaction is the same regardless of the pathway taken, as
long as initial and final states are the same.
Equilibrium
Q5. For the reaction N₂ + 3H₂ ⇌ 2NH₃, what happens if pressure is increased?
. Equilibrium shifts to the right (towards fewer gas molecules).
Q6. What is the equilibrium constant expression for the reaction:
2SO₂ + O₂ ⇌ 2SO₃ ?
. K=\frac{[SO_3]^2}{[SO_2]^2[O_2]}
Electrochemistry
Q7. In a galvanic cell, which electrode is the anode?
. The electrode where oxidation occurs.
Q8. What is the standard reduction potential of a hydrogen electrode?
0.00 V (defined reference).
Kinetics
Q9. How does a catalyst affect a chemical reaction?
It lowers the activation energy, increasing the reaction rate without being consumed.
Q10. What is the rate law for a reaction?
An equation that relates the reaction rate to the concentration of reactants, e.g., Rate =
k[A]^m[B]^n.
Q11. What happens to the freezing point of a solution when solute is added?
, The freezing point decreases (freezing point depression).
Q12. Define molarity.
. Molarity (M) = moles of solute ÷ liters of solution.
Atomic Structure & Bonding
Q13. What is the electron configuration of oxygen?
. 1s² 2s² 2p⁴
Q14. Define electronegativity.
A14. The tendency of an atom to attract electrons in a chemical bond.
Q15. Which bond is more polar: C–H or O–H?
. O–H, because oxygen is more electronegative than carbon.
States of Matter
Q16. What is the ideal gas law?
. PV=nRT
Q17. At constant temperature, what happens to pressure if volume decreases?
A17. Pressure increases (Boyle’s Law).
Q18. Define molar volume at STP.
. 22.4 L per mole of gas.
Thermochemistry
Q19. What is specific heat capacity?
. The amount of heat required to raise 1 g of a substance by 1°C.
Q20. Endothermic vs. exothermic reaction?
. Endothermic absorbs heat; exothermic releases heat.
Q21. What is ΔH for a reaction at constant pressure?
. The heat exchanged with surroundings.
Equilibrium
Q22. What does Le Châtelier’s Principle state?
. A system at equilibrium shifts to counteract changes in conditions.
Q23. If temperature increases in an exothermic reaction, which way does equilibrium
shift?
. To the left (reactants).
Q24. What does a large K value indicate?
. Products are favored at equilibrium.
