How to study for a general chemistry exam

A general chemistry exam tests two different skills, and most students only study for one of them. The first is recall: naming rules, solubility rules, strong acids, VSEPR shapes, periodic trends, the value of R. The second is problem setup: turning a word problem into the right chain of conversions. Rereading notes helps with neither. Recall needs practice at retrieving facts, and problem solving needs practice at working problems cold.

Separate what you memorize from what you practice

Go through your syllabus and sort each topic into one of two lists.

Memorize (flashcards work well):

Metric prefixes and unit equivalents (1 atm = 760 mmHg = 101.325 kPa)
Polyatomic ions and naming rules for ionic compounds, molecular compounds and acids
Solubility rules and the seven strong acids
Oxidation number rules
Electron configuration exceptions (chromium and copper) and the direction of each periodic trend
VSEPR electron and molecular geometries with their bond angles
The types of intermolecular forces, in order of strength

Practice (worked problems):

Significant figures and dimensional analysis
Molar mass, percent composition and empirical formulas
Molarity and dilution
Stoichiometry, limiting reactant and percent yield
Calorimetry and Hess's law
Photon energy and wavelength
Gas law problems

Formulas sit in both lists. You need to recall q = mc delta T instantly, and you also need to have used it enough to know which mass and which temperature change go into it.

Quiz yourself instead of rereading

Rereading feels productive because the material looks familiar. Familiar isn't the same as retrievable, and an exam asks you to retrieve. Testing yourself, by covering the answer, producing it and then checking, builds the memory you'll actually use. The testing effect covers the research. For the memorize list, that means flashcards you answer before flipping. For the practice list, it means problems you start from a blank page, not ones you follow along with in the solutions.

Space it out

Chemistry is cumulative. Stoichiometry uses molar mass, which uses the mole, which uses dimensional analysis. If unit 4 has faded by the time you reach unit 6, unit 6 feels much harder than it is. Short daily sessions that bring back older material beat a long session the night before. See what spaced repetition actually does for how the scheduling works.

Mix problem types

A homework set on limiting reactant has only limiting-reactant problems, so you know the method before you read the question. An exam doesn't tell you. Once you've learned a few problem types, practice them shuffled together so you have to recognize which method each problem needs. Is it a dilution, a mole-ratio problem or a gas law problem? Interleaving vs. blocking explains why mixing feels harder and works better.

A plan for the two weeks before a midterm

Days 14 to 10: Make sure you have all the material in front of you. Build or pick flashcards for everything on the memorize list, and start reviewing them daily. Redo two or three homework problems of each type without looking at the solutions.

Days 9 to 5: Work one timed practice problem set, mixed, every other day. Mark every miss as a recall gap (you forgot the fact) or a setup gap (you knew the facts and couldn't build the chain). Recall gaps go into your flashcards. Setup gaps get three more problems of that type.

Days 4 to 2: Take a full practice exam under time. Your professor's old exams are the best source if they're posted. Review every miss.

The day before: Light review of your flashcards and a few problems. No new material.

For a cumulative final, stretch this out and give the earliest units more review, not less. Studying for a cumulative final vs. a unit test covers the differences.

Set up every calculation the same way

Most lost points on calculation questions come from setup, not from arithmetic. Use one habit every time:

Write down what you're given, with units.
Write down what you're looking for, with units.
Build a dimensional analysis chain that cancels units from one to the other.
Check that the answer is reasonable, then round to the right significant figures.

The full stoichiometry version is in stoichiometry step by step. Gas problems add one rule: temperature goes in kelvin. See the ideal gas law with worked examples.

Traps that cost points

Changing subscripts to balance an equation. Only coefficients change.
Celsius in a gas law. Always convert to kelvin.
Comparing grams to find the limiting reactant. Compare the product each reactant can make.
Sign errors in thermochemistry. Exothermic means negative delta H for the system.
Confusing electron geometry with molecular geometry. Water has a tetrahedral electron geometry and a bent molecular shape.
Rounding too early. Keep extra digits until the final answer.
Using C1V1 = C2V2 for a titration. It only works for dilution; a titration needs the mole ratio. See C1V1 = C2V2 explained.

Use tools to check, not to replace, your work

A calculator that does the whole problem helps only after you've tried it yourself. Solve first, then check with the molar mass calculator, dilution calculator or ideal gas law calculator. If your answer doesn't match, find the step where it went wrong. That's where the learning happens. For lab reports, the error propagation calculator handles uncertainty.

Know the whole course

A map of the course makes it easier to see what's coming and what each unit depends on. What's in General Chemistry I lists all 13 units in order. If you're taking biology or physics in the same year, first-year science courses: biology, chemistry and physics shows how the six intro courses fit together, and how to study for a physics exam covers the physics side.

Encodr's free General Chemistry I flashcards cover the memorize list and the calculations, unit by unit, on a spaced-repetition schedule.