AAMC MCAT Chemical and Physical Foundations 1 β Questions and Answers
Question 1: What does a negative ΞG value indicate about a chemical reaction?
- The reaction is spontaneous and releases free energy (Correct answer)
- The reaction requires energy input to proceed
- The reaction is at equilibrium
- The reaction is endothermic
Correct answer: The reaction is spontaneous and releases free energy
A negative ΞG (exergonic reaction) indicates spontaneity β the reaction releases free energy and proceeds without added energy.
Question 2: According to Boyle's Law, if volume is halved at constant temperature, what happens to pressure?
- Pressure doubles (Correct answer)
- Pressure halves
- Pressure stays the same
- Pressure quadruples
Correct answer: Pressure doubles
Boyle's Law states pressure and volume are inversely proportional at constant temperature: halving volume doubles pressure.
Question 3: What is the significance of pH = pKa in a buffer solution?
- The acid and conjugate base are in equal concentrations (Correct answer)
- The solution is maximally acidic
- The buffer capacity is zero
- All acid has been deprotonated
Correct answer: The acid and conjugate base are in equal concentrations
At pH = pKa (Henderson-Hasselbalch midpoint), [HA] = [Aβ»], meaning exactly half the acid is dissociated and buffer capacity is maximal.
Question 4: Which quantum number describes the shape of an atomic orbital?
- Azimuthal quantum number (l) (Correct answer)
- Principal quantum number (n)
- Magnetic quantum number (ml)
- Spin quantum number (ms)
Correct answer: Azimuthal quantum number (l)
The azimuthal quantum number (l) defines orbital shape: l=0 is spherical (s), l=1 is dumbbell-shaped (p), l=2 is d.
Question 5: What does a high Reynolds number indicate about fluid flow?
- Turbulent flow where inertial forces dominate (Correct answer)
- Laminar flow with smooth streamlines
- Viscous-dominated creeping flow
- Incompressible inviscid flow
Correct answer: Turbulent flow where inertial forces dominate
A high Reynolds number (>4000) signals turbulent flow where inertial forces overwhelm viscous forces, creating chaotic mixing.
Question 6: What is the stereochemical outcome of an SN2 reaction?
- Inversion of configuration (Walden inversion) (Correct answer)
- Retention of configuration
- Complete racemization
- Formation of a planar carbocation intermediate
Correct answer: Inversion of configuration (Walden inversion)
SN2 reactions proceed via a backside attack, resulting in complete inversion of the stereocenter's configuration.
AAMC MCAT Chemical and Physical Foundations 1
What does a negative ΞG value indicate about a chemical reaction?