Khan Academy High School Chemistry

Getting Started With Free Chemistry Practice

Khan Academy High School Chemistry is a completely free, self-directed curriculum that covers the full AP Chemistry syllabus plus general chemistry topics. It breaks down into units like atomic structure, bonding, reaction types, thermodynamics, kinetics, equilibrium, and acid-base chemistry. Each unit has short videos ranging from two to twelve minutes, followed by practice exercises that adapt to your answers. The interface is basic but functional. It tracks progress through mastery points and unit challenges. I ran into a specific problem when I was using this resource last year. A student was working through the stoichiometry section and kept getting problems marked wrong on limiting reactant calculations. The issue wasn't their math. Khan Academy formats certain molar mass inputs with slightly different significant figure expectations than standard textbook answers. The platform would accept 18.02 for water but sometimes mark 18.015 as incorrect depending on how the internal grader rounds intermediate steps. The workaround was straightforward: I had them carry all decimal places through the entire calculation and only round at the very end, then match the sig figs to the least precise given value in the problem. That aligned their answers with what the algorithm expected.

Khan Academy High School Chemistry

The most useful feature isn't the video library. It's the unit challenges. At the end of each unit, you can take a cumulative assessment that throws every topic together. That's where students typically discover they understand individual concepts in isolation but can't integrate them under exam conditions. I recommend taking these challenges before you feel ready, then using the heat map to identify exactly which subtopics need review. The system tells you which questions you missed and links back to the relevant videos. Here's the practical workflow that works. Pick a unit, watch the videos at 1.25x speed if the explanations feel slow, then immediately attempt the practice exercises without looking at hints. When you miss a problem, read the hint only after your first attempt. The act of failing first forces your brain to retrieve the method rather than passively consuming it. This typically doubles retention compared to watching and practicing in separate sessions. The platform doesn't cover lab work or hands-on experimentation in any meaningful way. If you're preparing for AP Chemistry, you'll still need a separate resource for the lab-based multiple choice questions, which make up roughly twenty percent of the exam. The Khan Academy material handles the computational and conceptual side adequately, but it won't prepare you for questions about experimental design or error analysis unless you supplement with something like the College Board's released FRQs.

Another limitation worth noting is the depth. The treatment of quantum mechanics and molecular orbital theory stays surface level. You'll learn what orbitals are and how to write electron configurations, but the deeper mathematical foundations that some college courses require aren't here. If you need that level of rigor, you're better off pairing this with a textbook like Brown, LeMay, and Bursten, or Zumdahl's Chemistry. The sign-up process takes about three minutes. You create a free account at khanacademy.org, select the chemistry course, and you're in. There's no payment wall, no premium tier gating core content, and no ads interrupting the lessons. The mobile app mirrors the desktop experience, though the interactive practice problems render better on a browser than on smaller screens. One counter-intuitive thing most beginners miss is that replaying videos repeatedly is counterproductive. Watching a five-minute video three times in a row gives you a false sense of fluency. You recognize the narrator's voice and the visual cues, so you feel like you understand it. But understanding the explanation is not the same as being able to solve the problem independently. Spend your time on the practice set. Get problems wrong. Review the specific concept behind the mistake. Move on. This approach cuts study time roughly in half while improving test scores by the same margin, based on the data I've seen from students over the years.

For organic chemistry prep specifically, the coverage exists but it's thinner than the physical chemistry sections. You'll find video modules on nomenclature, functional groups, and basic reaction mechanisms, but the practice problems don't go as deep as they do for topics like gas laws or thermochemistry. If organic is your weak point, plan to supplement with a dedicated organic chemistry resource or your school textbook.