AP Chemistry Exam Review

What are the 6 strong acids?

HCl, HBr, HNO3, HClO4, HI, H2SO4

What are the 8 strong bases?

LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

What unit goes on an equilibrium constant?

No Units

What is the equation for a zero order reaction?

[A]t - [A]0 = -kt

What is the equation for a first order reaction?

ln[A]t - ln[A]0 = -kt

What is the equation for a second order reaction?

1/[A]t - 1/[A]0 = kt

How do you convert Ka to pKa?

pKa = -logKa

What equation do you use to convert Ka to Kb?

[Ka][Kb] = 1.0 X 10^-14 = Kw

How do you find the mole fraction?

Dividing the number of moles of "A" by the total number of moles of gas

How does Q relate to K in terms of equilibrium?

If Q>K, the reactants are favored. If Q

What is Q?

Reaction Quotient (Products/Reactants)

What does F stand for in electrochemistry?

Faraday's Constant = 96,485 C/mole-

What value of ΔG° results in a thermodynamically favorable reaction?

ΔG° < 0

What value of ΔG° results in a thermodynamically unfavorable reaction?

ΔG° > 0

What does ° mean when attached to a value like ΔG?

Find ΔG° at standard conditions (1atm, 25°C, 1M)

What value of ΔH° results in a thermodynamically favorable reaction?

ΔH° < 0

What value of ΔH° results in a thermodynamically unfavorable reaction?

ΔH° > 0

What value of ΔS° results in a thermodynamically favorable reaction?

ΔS° > 0

What value of ΔS° results in a thermodynamically favorable reaction?

ΔS° < 0

Why does Na have a smaller ionic radius than K?

Na has less electron shells in the cloud than K, thus the radius of Na is smaller

Why does Na have a larger ionic radius than Cl?

Na has less protons than Cl, which results in a smaller effective nuclear charge in Na than that of Cl. The protons pull the electrons closer to the nucleus, so Cl has a smaller radius.

What is the most electronegative element?

Fluorine

Which element has the largest ionic radius based on periodic trends?

Francium

Which element has the higher ionization energy, Oxygen or Fluorine? Explain.

Fluorine has a higher ionization energy than Oxygen because Fluorine is more electronegative. This means that F has a stronger attraction for electrons, which causes O to have a lower ionization energy.

If Q

No

What compounds/molecules are always soluble in water?

Nitrates, Acetates, Sulfates, Ammonium, Halogens, and Alkali Metals (Group 1)

What mixtures make buffers?

Weak acid and its conjugate base or a weak base and its conjugate acid

If buffers have more conjugate acid than base, are they more likely to absorb more base or acid?

Base

If buffers have more conjugate base than acid, are they more likely to absorb more base or acid?

Acid

How many sig figs should you apply to all your AP Chem exam answers?

3 sig figs

What is the geometry of a molecule with 4 bonds and no unshared pairs?

Tetrahedral

What is the bond angle of a tetrahedral molecule?

109.5°

What is the geometry of a molecule with 3 bonds and 1 unshared pair?

Trigonal Pyramidal

What is the bond angle of a trigonal pyramidal molecule?

107°

What is the geometry of a molecule with 2 bonds and 2 unshared pairs?

Bent

What is the bond angle of a bent molecule?

105°

What is the geometry of a molecule with 3 bonds and no unshared pairs?

Trigonal Planar

What is the bond angle of a trigonal planar molecule?

120°

What is the geometry of a molecule with 2 bonds and 1 unshared pair?

Angular

What is the bond angle of an angular molecule?

117°

What is the geometry of a molecule with 2 bonds and no unshared pair?

Linear

What is the bond angle of a linear molecule?

180°

What is the geometry of a molecule with 6 bonds and no unshared pair?

Octahedral

What is the bond angle of an octahedral molecule?

90°

What is the geometry of a molecule with 5 bonds and 1 unshared pair?

Square Pyramidal

What is the bond angle of a square pyramidal molecule?

90° and 180°

What is the geometry of a molecule with 4 bonds and 2 unshared pairs?

Square Planar

What is the bond angle of a square planar molecule?

90°

What is the geometry of a molecule with 3 bonds and 3 unshared pairs?

T-Shaped

What is the bond angle of a T-Shaped molecule?

90° and 180°

What is the geometry of a molecule with 5 bonds and no unshared pair?

Trigonal Bipyramidal

What is the bond angle of a Trigonal Bipyramidal molecule?

90° and 120°

What is the geometry of a molecule with 4 bonds and 1 unshared pair?

See-Saw

What is the bond angle of a Seesaw molecule?

87° and 117°

What is the geometry of a molecule with 3 bonds and 2 unshared pairs?

Trigonal Planar

What is the bond angle of a Trigonal Planar molecule?

120°

Order the following IMFs from strongest to weakest

Dipole-Dipole, LDFs, Ion-Dipole, Hydrogen Bonding

Ion-Dipole > Hydrogen Bonding > Dipole-Dipole > LDFs

When an element is oxidized in a reaction, what happens to the electrons and the oxidation number?

The electrons increase and the oxidation number decreases

When an element is reduced in a reaction, what happens to the electrons and the oxidation number?

The electrons decrease and the oxidation number increases

What does a hydrocarbon react with in a combustion reaction?

O2

What is produced from a combustion reaction?

H2O and CO2

What are the 4 ways to speed up the rate of a reaction?

Increase temperature, add a catalyst, increase reactant surface area, and increase reactant concentration

If the slow step is first in elementary reactions, what is the rate law?

The reactants to the power of their coefficient

Will a slow step have a higher or lower activation energy?

Higher activation energy

If ΔH is negative, is the reaction exothermic or endothermic?

Exothermic

If ΔH is positive, is the reaction exothermic or endothermic?

Endothermic

How can you determine the pKa of a solution using a titration curve diagram?

Evaluate the pH of the half-equivalence point of the titration curve

When a strong acid and strong base are titrated, what will the equivalence pH value be?

pH = 7

When a strong acid and weak base are titrated, what will the equivalence pH value be?

pH < 7

When a weak acid and strong base are titrated, what will the equivalence pH value be?

pH > 7

When a weak acid and weak base are titrated, what will the equivalence pH value be?

pH = 7

At the half equivalence point, what is the relation between the acid and conjugate base?

[HA] = [A-]

Why is there no such thing as an ideal gas?

Gas molecules take up space because they have an atomic radius

Why can an element like Xenon break the octet rule?

Xenon has D-Orbitals in the valence shell, meaning it can accomodate more than 8 electrons

Will the voltage of electrolysis be greater or less than 0? Explain.

The voltage will be less than because electrolysis requires an external source of energy and the reaction is unfavorable.

Will the voltage of a galvanic cell be greater or less than 0? Explain.

The voltage will be greater than because galvanic cells are favorable and generate electricity.

What equation can you use to calculate time or mass in a question regarding electroplating?

mass = AtM/Fe-

How can you calculate the empirical formula using the percent composition of elements?

Convert % to g in 1:1 ratio, convert to moles, then divide by the smaller amount of moles to find the ratios

If the reported percentage of an element in a sample is less than expected, what can you understand from this?

The sample is impure

Why would HCl have a weaker coulombic attraction than CaS? Justify using Coulomb's Law.

CaS has a stronger coulombic because the charge magnitude in CaS is +2 and -2, rather than +1 and -1 in HCl. Coulomb's law dictates that if the charge magnitude for a compound is increased, the attraction is therefore increased.

What are 4 characteristics of ionic bonds?

Metal + nonmetal, brittle, high melting points, and conduct electricity when dissolved

What are 3 characteristics of covalent bonds?

Nonmetal + nonmetal, low melting points, non-conductive of electricity when dissolved

Which of the following has more energy in terms of bonding?

C-----C OR C=====C

C=====C

What type of metallic alloy involves replacing atoms with other metallic atoms?

Substitutional Alloy

What type of metallic alloy involves small atoms in spaces between atoms of the main element?

Interstitial Alloy

When a structure has resonance, what does that mean?

The molecule has two valid lewis structures

How can hybridization of an element in a compound be determined?

Count the bonding domains (include unshared pairs)

Will there ever be dipole-dipole forces in a nonpolar molecule?

No

What are the 3 elements that, when paired with a hydrogen atom, can create hydrogen bonding?

Nitrogen, Oxygen, and Fluorine

Rank the following solids from highest to lowest melting points

Ionic, Covalent Network, Molecular

Covalent Network > Ionic > Molecular Solids

According to Maxwell-Boltzmann Distribution graphs, what happens to the velocity and kinetic energy of molecules when the temperature increases?

The velocity and kinetic energy increase

What mnemonic can be used to remember the approximate ideal conditions for an ideal gas?

HoT LiPs (high temperature, low pressure)

What does the phrase "Like dissolves like" mean?

note : DO NOT USE THIS TERM ON THE AP EXAM

Polar molecules dissolve in polar solvents, nonpolar molecules in dissolve nonpolar solvents

When there an outlier on an absorbance graph that is too high, what likely caused it?

The cuvette was contaminated by a solution with a higher concentration

When there an outlier on an absorbance graph that is too low, what likely caused it?

The solution in the cuvette was diluted with distilled water

When KCl and AgNO3 react, what will the spectator ions be and what will be the resulting precipitate?

Spectator : K, NO3

Precipitate : AgCl

What mnemonic can be used to remember REDOX reactions?

OIL RIG or LEOGER

What is the ONLY exception to oxygen having a charge of -2?

H2O2 (peroxide)

What is the total oxidation state of any compound?

0

How do you determine the total order of a reaction when given the rate law?

Add the exponents of each compound in the rate law