AP Chemistry Exam Review Practice Flashcards

Comprehensive practice flashcards for AP Chemistry covering units 0 through 9 based on lecture notes, including stoichiometry, kinetics, equilibrium, and thermodynamics.

When calculating with significant figures, what is the rule for addition and subtraction?

Use the lowest number of decimal places (labeled as lowest number of sig figs in notes) from the values provided and round the final answer accordingly.

What is the 'swap and drop' method in chemical formula writing?

A technique to balance charges where the numerical value of the cation's charge becomes the subscript of the anion, and the numerical value of the anion's charge becomes the subscript of the cation.

According to the solubility rules, which cation groups are always soluble in water?

All Alkali metals ($K^+$, $Na^+$, $Li^+$) and Ammonium ($NH_4^+$).

How is the average atomic mass of an element calculated using isotopes?

$$(\text{atomic mass}_1)(\% \text{ abundance}_1) + (\text{atomic mass}_2)(\% \text{ abundance}_2) = \text{Average atomic mass}$$

What does a Mass Spectroscopy graph indicate about an element?

The number of spikes represents the number of isotopes, the position on the x-axis indicates the atomic mass of isotopes, and the height of the spikes represents the relative abundance in percentage.

What is the difference between an Empirical Formula and a Molecular Formula?

An empirical formula is the simplest ratio of elements in a compound, while the molecular formula is the actual formula for the substance.

Which quantum number defines the distance of an electron from the nucleus?

The Principle quantum number (n), which corresponds to the row (1-7) on the periodic table.

How does Coulomb's Law relate distance to the force of attraction between charges?

The force of attraction is inversely proportional to the square of the distance ($R^2$); a greater distance results in less force between the nucleus and electrons.

What is the trend for Atomic Radius on the periodic table?

Atomic radius increases moving down a group and decreases moving to the right across a period.

Define Ionization Energy and its periodic trend.

The energy required to remove an electron; it decreases moving down a group and increases moving right across a period.

What are the characteristics of Ionic Compounds?

They form crystal lattices, have high melting and boiling points, are hard and brittle, act as good insulators as solids, and conduct electricity when liquid or aqueous.

What is Metallic Bonding?

A bond where metallic cations are attracted to a delocalized 'sea' of valence electrons.

What determines formal charge in a Lewis diagram?

$$\text{Formal charge} = \text{Valence electrons} - (\text{lone electrons} + \text{bonded electrons})$$

What is the molecular geometry and bond angle for an $sp^2$ hybridized atom?

Trigonal planar with $120$ degree bond angles.

Identify the types of bonds present in a triple bond.

One sigma ($\sigma$) bond and two pi ($\Pi$) bonds.

What are London Dispersion Forces (LDFs)?

Short-lived, weak forces present in nonpolar substances caused by temporary dipoles as electron clouds shift.

What are the three elements that can form Hydrogen bonds when bonded to Hydrogen?

Fluorine, Oxygen, and Nitrogen (FON).

State the Ideal Gas Law equation.

$$PV = nRT$$

According to the Kinetic Molecular Theory, what is the relationship between temperature and kinetic energy?

Average kinetic energy is directly proportional to the absolute temperature ($KE_{Avg} = \frac{3}{2}RT$).

What is the Beer-Lambert Law formula?

$A = ELC$ (where $A$ is absorbance, $E$ is molar absorptivity, $L$ is path length, and $C$ is molarity).

Distinguish between physical and chemical changes.

A physical change affects the appearance or state without changing composition; a chemical change involves breaking and rebonding to create a new substance with different properties.

What is the formula for Percent Yield?

$$\text{\% Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100$$

Define the equivalence point in a titration.

The point where the number of moles of titrant and the number of moles of analyte are stoichiometrically equal.

In Redox reactions, what do 'Oxidation' and 'Reduction' refer to?

Oxidation is the loss of electrons (increase in oxidation number); Reduction is the gain of electrons (decrease in oxidation number).

What is Collision Theory's requirement for a successful reaction?

Molecules must collide at the correct speed (having enough energy to overcome activation energy) and with the correct orientation.

Define the first-order half-life formula.

$$T_{1/2} = \frac{0.693}{k}$$

What is the role of a Catalyst in chemical kinetics?

It speeds up a reaction by providing an alternative pathway with a lower activation energy ($E_A$) without being consumed.

What is the difference between an endothermic and exothermic process?

Endothermic absorbs heat ($+\Delta H$), making the surroundings colder; Exothermic releases heat ($-\Delta H$), making the surroundings hotter.

What is Hess's Law?

The principle that the total enthalpy change of a reaction is the same regardless of whether it occurs in one step or a series of steps.

What is the Equilibrium Constant ($K_c$) expression for the reaction $aA + bB \rightleftharpoons cC + dD$?

$K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$, excluding solids and pure liquids.

What happens if $Q_c > K_c$ in a reversible reaction?

The ratio of products to reactants is too large; the reaction will shift towards the reactants to reach equilibrium.

According to Le Chatelier's Principle, how does a decrease in volume affect a gaseous reaction?

The reaction will shift towards the side with fewer moles of gas.

What is the value of $K_w$ at $25^{\circ}\text{ C}$?

$$K_w = [H^+][OH^-] = 1.0 \times 10^{-14}$$

Name the six strong acids mentioned in the notes.

$HCl$, $HBr$, $HI$, $HNO_3$, $H_2SO_4$, and $HClO_4$.

What is the Henderson-Hasselbalch equation used for buffers?

$$pH = pK_a + \log\left(\frac{[\text{base}]}{[\text{acid}]}\right)$$

Define Entropy ($S$).

A measure of the energy lost to molecular disorder or randomness in a sample.

Under what condition is a reaction 'thermodynamically favorable'?

When the Gibbs Free Energy change ($\Delta G$) is negative ($\Delta G < 0$).

In an electrochemical cell, what is the function of a salt bridge?

It allows ions to flow between solutions to balance the charge as oxidation and reduction occur.

What is Faraday's Constant?

$$96485\text{ coulombs} = 1\text{ mole of electrons}$$