If you’re pre-med and sitting in gen chem right now, you’ve probably wondered whether all those equilibrium problems and Lewis structures will matter later. Will you see them again? Or is chemistry just a box to check on the way to the “real” medical stuff? This article lays out where chemistry lives on the MCAT and what that means for the classes you’re taking now. So, how much chemistry is on the MCAT?
Quite a lot: chemistry shows up in two of the MCAT’s four sections, and it’s a major part of one of them. The Chemical and Physical Foundations of Biological Systems section (usually called Chem/Phys) leans heavily on general chemistry, organic chemistry and biochemistry, with physics mixed in. The Biological and Biochemical Foundations of Living Systems section (Bio/Biochem) is mostly biology and biochemistry, but it still expects you to use basic gen chem and orgo ideas. CARS and Psych/Soc aren’t chemistry sections. For exact weights, check the AAMC’s official content outline, not a number quoted on a forum.
How Is the MCAT Organized?
The MCAT has four scored sections, and each one is scored separately. According to the AAMC’s page on what’s on the MCAT exam, the layout looks like this:
| Section | Questions | Time | Chemistry? |
|---|---|---|---|
| Chemical and Physical Foundations of Biological Systems | 59 | 95 minutes | Yes, a large share |
| Critical Analysis and Reasoning Skills (CARS) | 53 | 90 minutes | No |
| Biological and Biochemical Foundations of Living Systems | 59 | 95 minutes | Yes, mostly through biochemistry |
| Psychological, Social, and Biological Foundations of Behavior | 59 | 95 minutes | Very little |
Each section is scored from 118 to 132, so total scores run from 472 to 528. The content time adds up to a little over six hours, and the whole seated day runs about seven and a half hours once you count breaks and tutorials.
The AAMC can adjust details over time. Before you plan your prep, read the current version of their pages, not a screenshot from three years ago.
Where Does General Chemistry Show Up?
General chemistry is one of the main pillars of the Chem/Phys section. If you took two semesters of gen chem, most of the big topics will look familiar.
Expect to use ideas like these:
- Atomic structure, electron configurations and periodic trends
- Bonding, Lewis structures, molecular shape and intermolecular forces
- Stoichiometry and the mole concept
- Gas behavior and the ideal gas law
- Thermochemistry, enthalpy, entropy and Gibbs free energy
- Kinetics and equilibrium
- Acids, bases, buffers and titrations
- Solubility and solutions
- Electrochemistry and redox reactions
The twist is how the MCAT asks. Most questions sit inside a passage about a biological or medical situation. You might read about blood buffering, an enzyme’s environment, or a lab experiment, and then answer a question that’s really about Le Chatelier’s principle or pH. The chemistry is the same chemistry you learned in college. The packaging is different.
Gen chem also leaks into Bio/Biochem. You may need to reason about pH, energy or binding while answering a biology question, even if the question never says “chemistry.”
How Much Organic Chemistry Is on the MCAT?
Organic chemistry is on the MCAT, but it isn’t the full two-semester orgo course you might fear. The focus is on concepts that matter for biology and biochemistry.
That usually means things like functional groups, nomenclature basics, stereochemistry and chirality, how structure affects properties, and common reaction types involving carbonyls, alcohols and amines. Lab techniques such as extraction, distillation and chromatography also come up, along with spectroscopy basics like IR and NMR. Long synthesis chains and memorized lists of named reactions are much less of a focus than in a typical Orgo 2 final.
The practical point is this. If you understand orgo well enough to explain why a reaction happens, you’re in good shape. If you passed orgo by memorizing reaction cards the night before, you’ll need to rebuild that understanding before the MCAT.
Where Does Biochemistry Fit?
Biochemistry is where chemistry and biology meet, and it appears in both Chem/Phys and Bio/Biochem. For many test takers, it’s the topic that ties the whole exam together.
Plan to know amino acids (structure and properties), protein structure, enzyme kinetics, metabolism, and the basics of nucleic acids and lipids. A lot of this is chemistry in disguise. Amino acid charge at a given pH is an acid-base problem. Enzyme behavior is kinetics. Metabolism is a long story about energy and redox.
Many medical schools now list biochemistry as required or recommended. Requirements vary by school, so check each program you’re interested in.
So, How Much Chemistry Is on the MCAT in Practice?
In practice, chemistry in some form touches roughly half of the exam’s sections, and it’s central to Chem/Phys. The AAMC’s MCAT content outline lists the foundational concepts for each section and the approximate weight of each discipline, so that’s the place to check the current figures.
According to the AAMC’s outline, Chem/Phys is roughly 30% general chemistry, 15% organic chemistry and 25% first-semester biochemistry, with physics and biology making up the rest. Bio/Biochem is roughly 25% biochemistry, with about 5% each of general and organic chemistry. The AAMC rounds those figures to the nearest 5% and says they vary from test to test, so treat them as approximate and check the current outline. In broad strokes:
- Chem/Phys is built heavily on gen chem, with orgo, biochem and physics alongside it.
- Bio/Biochem is mostly biology and biochem, with some gen chem and orgo reasoning.
- CARS has no science content at all.
- Psych/Soc is mostly psychology and sociology, with a bit of biology.
That’s a lot of chemistry for an exam people think of as a “biology test.”
Why Your College Chemistry Classes Are MCAT Prep
The single most useful thing you can do for MCAT chemistry is learn your college chemistry properly the first time. Every lecture you actually understand is one less topic to relearn later.
Think about the timeline. Many pre-meds take gen chem in their first year and orgo in their second. The MCAT often comes a year or two after that. If you treated those courses as “learn it, dump it,” you’ll be relearning from scratch while also juggling biochem, physics and psych. If you built real understanding, your MCAT review becomes review instead of new learning.
Here’s how I’d treat each class:
- Gen Chem 1 and 2: Focus on the why behind equilibrium, acid-base chemistry, thermodynamics and kinetics. Expect to see these often.
- Orgo 1 and 2: Learn mechanisms as patterns (where electrons go and why), not as separate facts.
- Biochemistry: If your school offers it before the MCAT, take it seriously. It connects everything.
- Physics: Not chemistry, but it shares Chem/Phys with chemistry, so don’t neglect it.
Your chemistry grades also matter on their own. Medical schools look closely at science coursework, and strong chemistry grades help your application whether or not they help your score. If you want the bigger picture, our guide on how to get into medical school walks through prerequisites, the MCAT and the application timeline step by step.
How Should You Review Chemistry for the MCAT?
Start with what you already know, test yourself on it, and spend your time on the gaps. Rereading your old notes feels productive but doesn’t tell you what you’ve forgotten.
- Read the AAMC outline first. Mark each topic as solid, shaky or forgotten.
- Do practice questions early. They show which topics need work faster than any reading can.
- Practice with passages. MCAT chemistry is almost always wrapped in a scenario, so practice pulling the chemistry out of the story.
- Work without a calculator. The MCAT doesn’t provide one, so get comfortable with estimation, scientific notation and logs by hand.
- Use the AAMC’s official prep materials. They’re written by the people who write the test.
If you’re still in your chemistry courses, the same habit applies on a smaller scale. Timed, exam-style practice before a final is good training for the MCAT’s pace. If orgo is your current hurdle, our Org Chem 1 practice exam is modeled on the ACS final format and has a video solution for every question, so you can see exactly where your reasoning goes wrong.
The Chemistry You Learn Now Is the Chemistry You Use Later
How much chemistry is on the MCAT? Enough that it should shape how you take your college classes. General chemistry, organic chemistry and biochemistry run through the Chem/Phys section and show up again in Bio/Biochem, usually inside passages about living systems.
The good news is that you don’t need a separate secret strategy for MCAT chemistry. You need the solid understanding that strong chemistry courses are supposed to give you. Learn it well now, keep it fresh with practice questions, and check the AAMC’s official outline before you build your study plan. The work you put into gen chem and orgo now is the same work you’ll lean on when MCAT prep starts.