MCAT General Chemistry Study
Practice Questions with Latest
2025-2026 Correct Answers
GRADED A+
STP
- ANS - 0°C and 1 atm
Ideal Gas Law
- ANS - PV = nRT
At STP, 1 mol of gas will occupy ...
- ANS - 22.4 L
Characteristics of an Ideal Gas
- ANS - 1. Gas molecules have zero volume
2. Gas molecules exert no forces other than repulsive forces due to
collisions
3. Gas molecules make completely elastic collisions
4. The avg. kinetic energy of gas molecules is directly proportional to the
temperature of the gas
,Partial pressure of a gas (equation)
- ANS - Partial pressure equals the mole fraction of the gas (number of
moles of gas "i" divided by total number of moles of gas in sample) times
the total pressure.
Average Kinetic Energy (of gas)
- ANS - KEavg = (3/2)RT
(R = .08206 L atm K⁻¹ mol⁻¹ or 8.314 J K⁻¹ mol⁻¹)
Average kinetic energy applies to ALL gases, regardless of mass.
Diffusion
- ANS - Spreading of one gas into another gas or into empty space.
Approximated by Graham's Law.
Graham's law (diffusion)
- ANS -
Effusion
- ANS - Spreading of a gas from high pressure to very low pressure
through a "pinhole."
Graham's law (effusion)
- ANS - Where rates are effusion rates, and Ms are the molar masses of
the gases.
When do "real" gases deviate from ideal gas behavior?
- ANS - When molecules are close together:
,- volume becomes significant
- electrostatic forces become significant
- high pressure pushes molecules together
- low temperatures cause gas molecules to settle close together
How does Volume compare for real and ideal gases?
- ANS - V(real) > V(ideal)
How does Pressure compare for real and ideal gases?
- ANS - P(real) < P(ideal)
(PV)/(RT) Graph: Real vs. Ideal gas
- What is the cause of POSITIVE deviation?
- What is the cause of NEGATIVE deviation?
- ANS - - Positive deviation cause: molecular volume
- Negative deviation cause: attractive intramolecular forces
Kinetics vs. Thermodynamics
- ANS - Kinetics: deals with rate of reaction; how fast equilibrium is
achieved
Thermodynamics: deals with balance of reactants/products after
equilibrium reached; what equilibrium looks like
According to the Collision Model, two conditions must be met for a
collision to lead to a reaction:
, - ANS - 1. Colliding molecules must reach a threshold energy called
"activation energy."
2. Colliding molecules must have proper spatial orientation.
Effect of temperature on reaction rate
- ANS - Rate increases with temperature increase because more collisions
with adequate kinetic energy occur each second.
Factors affecting rate of reaction
- ANS - 1. Temperature
2. Pressure
3. Concentration of certain substances
Rate Law (fwd)
- ANS - Rate(fwd) = k [A]ⁿ¹[B]ⁿ²
(where n1 and n2 are the order of each respective reactant and n1 + n2 =
overall order of reaction)
How do you determine the rate law?
- ANS - Experimentally - NOT using the coefficients in the balanced
chemical equation!!!
Zero order rxn graph
- what do you plot?
- shape of graph?
Practice Questions with Latest
2025-2026 Correct Answers
GRADED A+
STP
- ANS - 0°C and 1 atm
Ideal Gas Law
- ANS - PV = nRT
At STP, 1 mol of gas will occupy ...
- ANS - 22.4 L
Characteristics of an Ideal Gas
- ANS - 1. Gas molecules have zero volume
2. Gas molecules exert no forces other than repulsive forces due to
collisions
3. Gas molecules make completely elastic collisions
4. The avg. kinetic energy of gas molecules is directly proportional to the
temperature of the gas
,Partial pressure of a gas (equation)
- ANS - Partial pressure equals the mole fraction of the gas (number of
moles of gas "i" divided by total number of moles of gas in sample) times
the total pressure.
Average Kinetic Energy (of gas)
- ANS - KEavg = (3/2)RT
(R = .08206 L atm K⁻¹ mol⁻¹ or 8.314 J K⁻¹ mol⁻¹)
Average kinetic energy applies to ALL gases, regardless of mass.
Diffusion
- ANS - Spreading of one gas into another gas or into empty space.
Approximated by Graham's Law.
Graham's law (diffusion)
- ANS -
Effusion
- ANS - Spreading of a gas from high pressure to very low pressure
through a "pinhole."
Graham's law (effusion)
- ANS - Where rates are effusion rates, and Ms are the molar masses of
the gases.
When do "real" gases deviate from ideal gas behavior?
- ANS - When molecules are close together:
,- volume becomes significant
- electrostatic forces become significant
- high pressure pushes molecules together
- low temperatures cause gas molecules to settle close together
How does Volume compare for real and ideal gases?
- ANS - V(real) > V(ideal)
How does Pressure compare for real and ideal gases?
- ANS - P(real) < P(ideal)
(PV)/(RT) Graph: Real vs. Ideal gas
- What is the cause of POSITIVE deviation?
- What is the cause of NEGATIVE deviation?
- ANS - - Positive deviation cause: molecular volume
- Negative deviation cause: attractive intramolecular forces
Kinetics vs. Thermodynamics
- ANS - Kinetics: deals with rate of reaction; how fast equilibrium is
achieved
Thermodynamics: deals with balance of reactants/products after
equilibrium reached; what equilibrium looks like
According to the Collision Model, two conditions must be met for a
collision to lead to a reaction:
, - ANS - 1. Colliding molecules must reach a threshold energy called
"activation energy."
2. Colliding molecules must have proper spatial orientation.
Effect of temperature on reaction rate
- ANS - Rate increases with temperature increase because more collisions
with adequate kinetic energy occur each second.
Factors affecting rate of reaction
- ANS - 1. Temperature
2. Pressure
3. Concentration of certain substances
Rate Law (fwd)
- ANS - Rate(fwd) = k [A]ⁿ¹[B]ⁿ²
(where n1 and n2 are the order of each respective reactant and n1 + n2 =
overall order of reaction)
How do you determine the rate law?
- ANS - Experimentally - NOT using the coefficients in the balanced
chemical equation!!!
Zero order rxn graph
- what do you plot?
- shape of graph?
