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MCAT General Chemistry Flashcards
50 question-and-answer cards covering General Chemistry as it is examined in MCAT. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the General Chemistry deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
Define Avogadro's number and its relation to the mole.
One mole contains $N_A = 6.022\times10^{23}$ particles (atoms, molecules, ions, etc.).
How do you convert between mass, moles, and number of particles?
$$n = \frac{m}{M}, \qquad N = n \cdot N_A$$ where $n$ = moles, $m$ = mass, $M$ = molar mass, $N$ = number of particles.
What volume does 1 mole of an ideal gas occupy at STP?
$22.4\ \text{L}$ at standard temperature and pressure ($0^{\circ}\text{C}$, $1\ \text{atm}$).
What does it mean to balance a chemical equation, and what principle requires it?
Adjusting stoichiometric coefficients so each element has equal atom counts on both sides, satisfying the law of conservation of mass. Only coefficients may change, never subscripts.
Balance the combustion of propane: $\ce{C3H8 + O2 -> CO2 + H2O}$.
$$\ce{C3H8 + 5O2 -> 3CO2 + 4H2O}$$
How do you identify the limiting reactant in a reaction?
Convert each reactant's amount to moles of product using stoichiometry; the reactant yielding the least product is limiting. It is fully consumed and determines the theoretical yield.
Define theoretical yield, actual yield, and percent yield.
Theoretical yield: maximum product predicted by stoichiometry. Actual yield: amount actually obtained. $$\%\text{ yield} = \frac{\text{actual yield}}{\text{theoretical yield}}\times 100\%$$
If a reaction has a theoretical yield of $\SI{40}{g}$ but produces $\SI{30}{g}$, what is the percent yield?
$$\frac{30}{40}\times100\% = 75\%$$
Describe synthesis (combination) and decomposition reactions.
Synthesis: two or more reactants combine into one product, $\ce{A + B -> AB}$. Decomposition: one compound breaks into two or more products, $\ce{AB -> A + B}$.
Describe single-displacement and double-displacement reactions.
Single displacement: $\ce{A + BC -> AC + B}$ (one element replaces another). Double displacement: $\ce{AB + CD -> AD + CB}$ (ions exchange partners, e.g., precipitation or neutralization).
What defines a combustion reaction of a hydrocarbon?
A hydrocarbon reacts with $\ce{O2}$ to produce $\ce{CO2}$ and $\ce{H2O}$, releasing energy (exothermic), e.g., $\ce{CH4 + 2O2 -> CO2 + 2H2O}$.
What is the difference between the rate-determining step and an intermediate in a reaction mechanism?
The rate-determining step is the slowest elementary step and governs the overall rate. An intermediate is a species produced in one step and consumed in a later step, so it does not appear in the overall equation.
What is a catalyst and how does it affect a reaction mechanism?
A catalyst provides an alternative pathway with lower activation energy, speeding up the reaction without being consumed. It appears in the mechanism but not in the overall balanced equation, and does not change $\Delta G$ or equilibrium.
How is the rate law of an elementary reaction determined?
For an elementary step, the rate law follows the molecularity directly from its coefficients: e.g., $\ce{A + B -> products}$ gives $\text{rate} = k[\ce{A}][\ce{B}]$. (This is NOT true for overall reactions, which require experimental determination.)
Define oxidation and reduction in terms of electrons.
Oxidation is the loss of electrons (oxidation number increases); reduction is the gain of electrons (oxidation number decreases). Mnemonic: OIL RIG — Oxidation Is Loss, Reduction Is Gain.
What are the roles of the oxidizing agent and reducing agent?
The oxidizing agent is reduced (it gains electrons, causing another species to be oxidized). The reducing agent is oxidized (it loses electrons, causing another species to be reduced).
State the key rules for assigning oxidation numbers.
Free elements = 0; monatomic ion = its charge; $\ce{O} = -2$ (except peroxides $-1$); $\ce{H} = +1$ (with metals $-1$); group 1 = $+1$, group 2 = $+2$; sum of oxidation numbers equals the overall charge of the species.
Determine the oxidation state of sulfur in $\ce{SO4^2-}$.
Oxygen is $-2$ each ($4\times -2 = -8$); overall charge $-2$, so $S + (-8) = -2$, giving $S = +6$.
State the zeroth law of thermodynamics.
If two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other — this defines temperature.
State the first law of thermodynamics.
Energy is conserved: the change in internal energy equals heat added minus work done by the system. $$\Delta U = q - w$$
State the second law of thermodynamics.
The total entropy of an isolated system never decreases in a spontaneous process: $\Delta S_{\text{universe}} \geq 0$. Systems tend toward states of higher disorder.
State the third law of thermodynamics.
The entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero: $$\lim_{T\to 0} S = 0$$
How does the Gibbs free energy equation determine spontaneity?
$$\Delta G = \Delta H - T\Delta S$$ A process is spontaneous when $\Delta G < 0$, at equilibrium when $\Delta G = 0$, and nonspontaneous when $\Delta G > 0$.
Compare endothermic and exothermic reactions in terms of $\Delta H$ and heat flow.
Exothermic: releases heat to surroundings, $\Delta H < 0$. Endothermic: absorbs heat from surroundings, $\Delta H > 0$.
What this deck covers
The General Chemistry deck follows the MCAT General Chemistry syllabus — 9 chapters and 40 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 5.6 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 151 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
General Chemistry flashcards FAQ
How many General Chemistry flashcards are in this MCAT deck?
50 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these MCAT flashcards free?
Yes. The preview here is free to read with no signup, and the full 50-card deck is free inside the Examius app.
What do the General Chemistry cards cover?
They follow the MCAT General Chemistry syllabus — 9 chapters and 40 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.