ACS CP Organic, Inorganic & Physical Chemistry 2 — Questions and Answers
Question 1: Which reagent converts a primary alcohol to an aldehyde without over-oxidizing to a carboxylic acid?
- KMnO₄ in acidic solution
- PCC (pyridinium chlorochromate) (Correct answer)
- CrO₃ in H₂SO₄
- Jones reagent
Correct answer: PCC (pyridinium chlorochromate)
PCC selectively oxidizes primary alcohols to aldehydes and stops there because it is a mild, anhydrous oxidant.
Question 2: In crystal field theory, which geometry produces the largest crystal field splitting (Δ) for the same metal and ligands?
- Tetrahedral
- Square planar
- Octahedral (Correct answer)
- Trigonal bipyramidal
Correct answer: Octahedral
Octahedral complexes have six ligands interacting with d orbitals along all three axes, producing the largest Δ.
Question 3: The Clausius-Clapeyron equation relates vapor pressure to temperature. What does the slope of ln(P) vs 1/T represent?
- -ΔHvap/R (Correct answer)
- ΔSvap/R
- ΔGvap/RT
- -R/ΔHvap
Correct answer: -ΔHvap/R
The Clausius-Clapeyron equation is d(ln P)/d(1/T) = -ΔHvap/R, so the slope equals -ΔHvap/R.
Question 4: Which of the following best describes a transesterification reaction?
- An ester reacting with an alcohol to exchange the alkoxy group (Correct answer)
- Hydrolysis of an ester with water
- Reduction of an ester to an alcohol
- Reaction of an acid chloride with an amine
Correct answer: An ester reacting with an alcohol to exchange the alkoxy group
Transesterification is the exchange of an alkoxy group between an ester and an alcohol, often acid- or base-catalyzed.
Question 5: For a coordination compound with formula [Co(NH₃)₄Cl₂]Cl, how many moles of ions are produced per formula unit when fully dissociated in water?
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
The complex ion [Co(NH₃)₄Cl₂]⁺ and one Cl⁻ counter-ion dissociate, giving 2 moles of ions per formula unit.
Question 6: Which thermodynamic quantity is minimized at constant temperature and pressure for a spontaneous process?
- Enthalpy (H)
- Entropy (S)
- Gibbs free energy (G) (Correct answer)
- Internal energy (U)
Correct answer: Gibbs free energy (G)
At constant T and P, a process is spontaneous when the Gibbs free energy decreases (ΔG < 0).
Question 7: In the E2 elimination reaction of (2R,3R)-2-bromo-3-methylbutane with KOtBu, which geometric requirement must the H and Br satisfy?
- Syn-periplanar arrangement (0°)
- Gauche arrangement (60°)
- Anti-periplanar arrangement (180°) (Correct answer)
- Eclipsed arrangement (120°)
Correct answer: Anti-periplanar arrangement (180°)
E2 elimination requires an anti-periplanar (180°) arrangement of the leaving group and the β-hydrogen for concerted removal.
ACS CP Organic, Inorganic & Physical Chemistry 2
Which reagent converts a primary alcohol to an aldehyde without over-oxidizing to a carboxylic acid?