How much physics is actually on the MCAT Chem/Phys section?

Roughly a quarter of the section. It is algebra-based and concentrated in fluids, circuits, thermodynamics, waves, sound and optics, usually applied to physiological or lab equipment scenarios. Rotational dynamics and detailed kinematics appear far less often than in a first-year physics course.

Do I have to memorise equations, and can I use a calculator?

No calculator is permitted, and no equation sheet is provided. A working set of formulas needs to be recalled, but the exam rewards estimation and dimensional reasoning more than precise computation — most numerical answers can be reached to one significant figure.

Should I study Chem/Phys separately or as part of full MCAT prep?

Content review is usually done section by section, then blended into full-length practice. Working Chem/Phys on its own is useful when a diagnostic shows this section lagging the others, since its physics and general chemistry content overlaps little with Bio/Biochem or Psych/Soc.

I keep running out of time on this section. What causes that?

Most often it is calculating precisely when estimating would do, and re-reading passages before looking at the questions. Sessions target both: choosing a triage order for the 10 passages, and practising the habit of scanning answer choices for spread before doing any arithmetic.

MCAT Chem/Phys

Graduate Tests · Test Prep

The Chemical and Physical Foundations of Biological Systems section is the first scored section of the MCAT: 59 questions in 95 minutes, built from roughly 10 passages plus 15 standalone questions. It draws mostly on general chemistry, algebra-based physics and biochemistry, with a smaller slice of organic chemistry, and it almost always frames that content in a biological or laboratory context — flow through a stenosed artery rather than a plain pipe, buffering in blood rather than a beaker. Sessions with Evelyn focus on reasoning from passage data and estimating numerically without a calculator, which is where most of the section's difficulty actually lives.

Start a session on MCAT Chem/Phys

What this covers

Fluids and circuits in physiological framing: continuity, Bernoulli, Poiseuille resistance, and the resistor/capacitor analogies used for membranes and nerve conduction
Acid-base and buffer work: pKa reasoning, Henderson-Hasselbalch, titration curve reading, amino acid protonation states and net charge at a given pH
Thermodynamics and electrochemistry sign conventions: ΔG, ΔG°', Keq, ΔG = -nFE°, galvanic versus electrolytic cells, and coupling to biochemical reactions
Separations and spectroscopy as they appear on the exam: chromatography, electrophoresis, IR functional group peaks, 1H NMR splitting, UV-Vis and Beer's law calculations
Calculator-free estimation: logs and antilogs, scientific notation, unit analysis, and deciding when an answer choice can be eliminated on magnitude alone
Passage triage and experimental interpretation: extracting the relevant equation or figure trend from a research-style passage under a roughly 95-second-per-question pace

Where learners get stuck

Applying Bernoulli and continuity in the same breath and concluding that a narrower vessel has higher pressure: Continuity says velocity rises when cross-sectional area falls, and intuition says 'squeezed means more pressure.' Bernoulli says the opposite for the pressure term. Students who memorised both equations separately never reconciled them, and MCAT passages deliberately set up narrowing-vessel scenarios.
Treating pH < pKa as meaning 'the group is negatively charged': Henderson-Hasselbalch is often memorised as an equation rather than as a statement about which form dominates. Under acidic conditions the protonated form dominates, so carboxylates are neutral COOH and amines are positive NH3+. This misfires constantly on amino acid net-charge and isoelectric point questions.
Losing the sign in ΔG = -nFE and in electrochemical cell setups: General chemistry courses teach anode-is-oxidation with a negative sign in galvanic cells and a positive sign in electrolytic cells, and biochemistry adds ΔG°' at pH 7. Students collapse these into one rule, then mislabel spontaneity for electron transport chain or battery passages.

What a session looks like

A typical session starts with a short diagnostic set of passage questions or discretes in one content area, worked aloud so reasoning is visible. Evelyn asks you to state which principle applies before any arithmetic, then pushes on the estimation step — what power of ten, what sign, which answer choices can go. Errors get traced back to whether the problem was a content gap, a misread figure or a timing decision, and the session usually ends with one worked example you reconstruct from scratch. Sessions are voice-based, so you talk through the physics rather than writing silently.

Helpful to know first

Two semesters of general chemistry, including equilibrium, acids and bases, thermodynamics and electrochemistry
Two semesters of algebra-based (or calculus-based) introductory physics covering mechanics, fluids, thermodynamics, electricity, magnetism, waves and optics
Organic chemistry through functional groups, common reaction mechanisms and spectroscopy
One semester of biochemistry, particularly amino acids, enzyme kinetics and metabolic thermodynamics
Comfort with logarithms, scientific notation and unit conversion without a calculator

Questions

How much physics is actually on the MCAT Chem/Phys section?: Roughly a quarter of the section. It is algebra-based and concentrated in fluids, circuits, thermodynamics, waves, sound and optics, usually applied to physiological or lab equipment scenarios. Rotational dynamics and detailed kinematics appear far less often than in a first-year physics course.
Do I have to memorise equations, and can I use a calculator?: No calculator is permitted, and no equation sheet is provided. A working set of formulas needs to be recalled, but the exam rewards estimation and dimensional reasoning more than precise computation — most numerical answers can be reached to one significant figure.
Should I study Chem/Phys separately or as part of full MCAT prep?: Content review is usually done section by section, then blended into full-length practice. Working Chem/Phys on its own is useful when a diagnostic shows this section lagging the others, since its physics and general chemistry content overlaps little with Bio/Biochem or Psych/Soc.
I keep running out of time on this section. What causes that?: Most often it is calculating precisely when estimating would do, and re-reading passages before looking at the questions. Sessions target both: choosing a triage order for the 10 passages, and practising the habit of scanning answer choices for spread before doing any arithmetic.