Chemistry Honors Final Review

Significant Figures Rules

1) all non-zero digits are significant

2) all zeros between non-zero digits are significant

3) zeros to the left of non-zeros are never significant

4) zeros to the right of non-zero digits are not significant unless there is a decimal point

Significant Figures Operation Rules

Multiplication/Division: Result has same number of sig figs as the least in the problem.

Addition/Subtraction: Result is rounded to the least number of decimal places in the problem.

What is a Colorimeter?

A device that measures the concentration of a solution by detecting how much light is absorbed by the solution.

What is a Calorimeter

A device used to measure heat transfer during chemical or physical changes.

Calorimetry Equation

q=mcΔT

q=heat (J)

m=mass (g)

c=specific heat (J/gC)

ΔT=Temp. Change (C)

What is a conductivity meter?

A device that measures how well a solution conducts electricity.

What is precision?

How consistent repeated measurements are

What is accuracy?

How close a measurement is to the true or accepted value.

Physical vs Chemical Change

Physical - does not create a new substance, atoms are not rearranged into different compounds

Chemical - converts one substance into another; atoms are rearranged

What are: Distillation, Filtration, Evaporation?

Distillation - separates by boiling point

Filtration - separates solids from liquids

Evaporation - removes a liquid, leaves behind solids

What are: Magnetism, Crystallization, Chromatography?

Magnetism - separates magnetic materials from non-magnetic ones

Crystallization - forms pure crystals from a solution

Chromatography - separates substances by how they move through a medium

What are: Centrifugation, Decanting, Sieving

Centrifugation - separates by density using spinning

Decanting - gently pouring off a liquid from a settled solid

Sieving - separates solids by particle size

Density Formula

D=m/v

m=mass

v=volume

Phase Change: Solid to Liquid and Liquid to Solid

melting and freezing

Phase Change: Liquid to Gas and Gas to Liquid

vaporization and condensation

Phase Change: Solid to Gas and Gas to Solid

sublimation and deposition

What is a homogeneous mixture?

A mixture that has a uniform composition throughout — the parts are evenly mixed and not visibly separate.

Most reactive metals

alkali metals

Least reactive metals

transition metals

Most reactive non metals

halogens

What is polarity?

A polar molecule has an uneven distribution of charge — one end is slightly positive, the other slightly negative.

How to determine molecular polarity?

1. If bonds are between atoms with different electronegativities, the bond is polar.

2. If the molecule is asymmetrical, it's polar.

What is more polar: Covalent or Ionic?

Ionic

How does polarity affect solubility?

polar dissolves polar, non-polar dissolves non-polar

What is the formula for average atomic mass?

1. Multiply each isotope's mass by its abundance (as a decimal)

2. Add the results together

Polyatomic Ions

ions that are made of more than one atom (Study Set on Google Classroom)

How do you name ionic compounds?

1. Metal name first

2. Nonmetal name ends in -ide

3. If the metal has more than one charge (transition metal):

Use Roman numerals

How do you name covalent compounds?

1. First Element: Use the full element name; add a prefix if there's more than one atom.

2. Second Element: Use a prefix + root of the element (first part of element) + -ide ending.

How do you name acids?

Hydro + 1 other element:

1. Start with "hydro-"

2. Add the root of the nonmetal

3. Add "-ic acid"

Hydro + >1 other elements:

1. No "hydro-"

2. Change ending

3. ate -> ic

4. ite -> ous

How does surface area affect solubility?

Greater surface area = faster dissolving

What is the Aufbau Principle?

Electrons fill lowest energy orbitals first

What is the Pauli Exclusion Principle?

No two electrons in the same orbital can have the same spin

What is Hund's Rule?

when filling atomic orbitals with electrons, they should be placed singly in each orbital of a given sublevel before any orbital is doubled

How many orbitals can each energy level hold?

1, 4, 9, 16

Energy Level Names

s, p, d, f

How many orbitals does each letter hold?

s=1, p=3, d=5, f=7

How many electrons per orbital?

2 electrons

What are allotropes?

Allotropes are different forms of the same element in the same physical state, with different atomic structures.

Carbon allotropes

Diamond, graphite, fullerene, graphene

Molecular vs Empirical Formula

Molecular: show actual elemental symbols and numbers of all atoms in a molecule

Empirical: most-reduced whole number ratio of each atom

Mass Percent Composition Formula

mass of element/mass of compound x 100

How do you convert an empirical formula to a molecular formula?

1. Find Empirical Molar Mass

2. Divide the given by that number

3. Multiply empirical subscripts by number found in step 2

Lewis Structures

(Look for worksheets/examples)

Molecular Geometry Shape: 2 bonds, 0 lone

linear

Molecular Geometry Shape: 3 bond, 0 lone

Trigonal Planar

Molecular Geometry Shape: 2 bond, 1 lone

Bent

Molecular Geometry Shape: 4 bond, 0 lone

tetrahedral

Molecular Geometry Shape: 3 bond, 1 lone

trigonal pyramidal

Molecular Geometry Shape: 2 bond, 2 lone

Bent

How do you determine if a molecule is polar?

Nonpolar is symmetrical

What is the formula for percent composition?

(Total mass of compound/Mass of element​)×100

What is stoichiometry?

calculating amounts of substances in chemical reactions using balanced equations.

Stoichiometry problems

(Look for worksheets/examples)

Avogdro's number

6.02 x 10^23

What is the volume of 1 mole of any gas at STP?

22.4 liters

How do you convert moles to ions?

Use Avogadro's number and multiply it by how many individual ions are present in a given number of moles of a substance.

How do you find the number of ions per formula unit of a compound?

How do you find the number of ions per formula unit of a compound?

What is a synthesis (combination) reaction?

A + B → AB

What is a decomposition reaction?

AB → A + B

What is a single replacement reaction?

A + BC → AC + B

What is a double replacement reaction?

AB + CD → AD + CB

What is a combustion reaction?

Cx​Hy​Oz​ + O2​→CO2​ + H2​O

What is the formula for percent yield?

(Theoretical Yield/Actual Yield​)×100

What is the formula that relates volume, pressure, and temperature for a gas?

(P1V1)/T1 = (P2V2)/T2

(In Kelvin)

Ideal Gas Law

PV=nRT

P = pressure (atm)

V = volume (L)

T = temperature (K)

R = Gas Constant (Varies depending on pressure unit)

n = mass/molar mass

mass = in grams

molar mass = g/mol

What formula relates pressure and temperature?

P1/T1 = P2/T2

(In Kelvin)

What is the formula that relates volume and pressure?

P1V1 = P2V2

STP conditions

- Temperature: 0°C or 273 K

- Pressure: 1 atm or 101.3 kPa

- Molar Volume: 1 mole of an ideal gas = 22.4 L

What are the conversions for the 3 pressure measurements?

1 atm

760 mmHg

101.3 kPa

Entropy Formula

△S of products minus △S of reactants

Enthalpy Formula

△H of products minus △H of reactants

What is entropy (ΔS)?

Entropy is a measure of disorder or randomness in a system.

List the phases in terms of increasing entropy

Solid, Liquid, Gas

What is activation energy?

energy needed to start a reaction

What is the heat of reaction?

The quantity of energy released or absorbed as heat during a chemical reaction

Exothermic vs Endothermic

-Exothermic is heat released

-Endothermic is heat absorbed

What is the formula for the equilibrium constant Keq?

A^aB^b / C^cD^d

When are products, reactant, or neither favored?

keq > 0 products

keq = 0 neither

keq < 0 reactants

What is the formula for specific heat?

q=m⋅c⋅ΔT

q = heat energy ( J)

m = mass (g)

c = specific heat capacity (J/g·°C)

ΔT = change in temperature

What Makes a Reaction Spontaneous (ΔH and ΔS)?

Negative Enthalpy, Positive entropy

Gibbs Free Energy Formula

∆G = ∆H - T∆S

Solids (s) and liquids (l) are not included in equilibrium expressions.

What does Keq stand for?

Equilibrium constant

What does Ksp stand for?

Solubility product constant

What states of matter are excluded from the Keq expression?

Solid and liquid

What is excluded from the Ksp expression?

everything except Aqueous Solutions

What doesn't have enthalpy?

elements

What is the dilution formula?

N1/​V1​=N2/​V2​

hat is the relationship between normality and molarity for diprotic acids?

N=M×2

What does pH + pOH always equal at 25°C (room temp)?

14

What is the formula connecting pH and [H⁺]?

pH=−log[H+]

What is the formula connecting pOH and [OH⁻]?

pOH=−log[OH−]

What is the relationship between [H⁺] and [OH⁻] at 25°C?

[H+][OH−]=1×10−14

How to find the oxidizing/reduction agent?

Label each element with its oxidation numbers. Oxidizing agent is the one that gained electrons (loses charge) and the reduction agent is the one that loses electrons (gained charge)

What does a positive q value mean in thermochemistry?

Endothermic

What does a negative q value mean in thermochemistry?

Exothermic

How do you determine if a bond is polar?

difference in electronegativity between atoms

What is the limiting reactant?

The reactant that is completely used up first in a chemical reaction

What are the steps to find the limiting reactant?

1. Convert grams of each reactant to moles

2. Divide moles of each reactant by its coefficient from the balanced equation

3. Compare values — the smallest result is the limiting reactant

Atomic Number

the number of protons in the nucleus of an atom