FINAL EXAM - Chemistry

Formula for density

D=M/V

Formula for Kinetic Energy

KE=m(v)²/2

How many significant figures do you need on an Add/Subtracting problem?

The least # to the right of the decimal.

How many significant figures do you need on a Multiple/Divide problem?

Least # of sig figs

A row is called a ______

Period

A column is called a _____ or ______

Group or family

How do you find # of neutrons?

Mass # - Atomic #

How do you find the empirical formula?

1. Change % to g

2. Convert g → mol

3. Divide by LEAST # of mol

4. Result = Subscript of each element

How do you find limiting reactant?

1. Convert from g of given elements to g of unknown

2. Whichever number is the LEAST, that is your answer. Whichever element gave you the lowest number is your limiting reactant.

Formula for % composition

Part/whole X 100

How to find % composition

1. Find mass of part & mass of whole

2. Find Part/Whole

3. Multiple by 100

What is an ionic compound?

Metal + Nonmetal

What is a molecular/covalent compound?

2 or more nonmetals

Combination/Synthesis Reaction

A+B → AB

Decomposition/Analysis Reaction

AB → A+B

Complete Combustion Reaction

Creates CO2 & H2O

Incomplete Combustion Reaction

Creates CO and H2O

How to find molecular formula

1. Convert % to g

2. Convert g→mol

3. Gram formula mass (GFM)/empirical formula mass (EFM)

4. Multiply subscripts by answer

Formula for % yield

Actual/Theoretical X 100

How to find % yield

1. Convert g of given to g of unknown (answer = Theoretical yield)

2. Divide given yield (actual yield) by theoretical yield

3. Put answer as a %

Solute

Substance that dissolves

Solvent

Substance that does the dissolving

Strong Acids

HCl, HBr, HI, HNO3, H2SO4, HClO4

Strong Bases

LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2

Spectator ions

ions that stay the same on BOTH sides of the reaction

or ions that are not used to create precipitate

Net ionic equation

The equation you get when you break an equation down to the simplest form.

Which ions are ALWAYS soluble

Alkali Metals

Neutralization Reaction produces a _____ and ______ ____

Water and Soluble Salt

Formula for Molarity

M=Mol/L

How to find molarity

1. Convert g→mol and ml→L

2. Divide mol/L

Formula for Dilution

(M1)(V1)=(M2)(V2)

How to find concentration by diluting?

1. Convert mL→L

2. Fill into M1V1=M2V2 equation

Oxidation

LOSS of Electrons (LEO)

Reduction

GAIN of electrons (GER)

How to find oxidation states of elements

1. Find charges for each atom

2. sum of charges MUST = 0 EXCEPT for when its an ion

Exothermic

NEGATIVE

Losing energy

Heat GIVEN OFF

Work done BY system ON surroundings

Endothermic

POSITIVE

Gaining energy

Heat ABSORBED

Work done ON system BY surroundings

Formula for Change in Internal Energy

deltaE=q+w

Formula for Work

W=Fd (F=force) (d=distance)

Formula for Calorimetry

q=mCdeltaT

Formula for Enthalpy of Reactions

Products-Reactants

How to find Enthalpy (deltaH)

1. Start with given mass and convert to mol

2. Put kJ over mol of element with given mass using coefficient from formula

Formulas for Waves

C=λv (Speed of light = wave length X frequency)

Ephoton = hv (energy = planks constant X frequency)

E=mc²

λ=h/mc

λ=h/mv

Possible values for quantum numbers

n=1 l=0 ml=0

n=2 l=0,1 ml=-1,0,1

n=3 l=0,1,2 ml=-2,-1,0,1,2

Formula for effective nuclear charge

Zeff = Z-S (atomic number - shielding costant)

Which way does Atomic Radii and Ionic Radii increase?

Left and Down

Which way does ionization energy, electron affinity, and electronegativity increase?

Up and Right

Ionic bond _________ electrons

Transfers

Covalent bond ______ electrons

Shares

Exceptions to the octet rule

H He Li Be B S P

sigma bonds

each bond counts as 1

pi bonds

each double bond counts as 1, each triple bond counts as 2

Formula for formal charge

Valence electrons - (# of bonds+free elecrons)

Lewis structures of ions ALWAYS go in _______

Brackets

How to determine if there are polar bonds

1. Find difference between electronegativity

   0-.2 = nonpolar .3-4 = polar

how to determine if a molecule is polar

1. If the central atom has free electrons

2. if the molecule has different outer atoms

How to find hyridization

1. count e- domains (each bonding domain = 1)(each free e- pair = 1)

2. Subtract by 1

Single bond

longest, weakest

Triple bond

shortest, strongest

Formula for partial pressure

Pressure of gas + pressure of gas + …….

How to convert to atm

1 atm = 760 torr, 760 mmHg, and 101.3kPa

Standard temp

273.15K

Combined Gas Law

P1 X V1 / Ti = P2 X V2 / T2

Ideal Gas Law

Pv=nRT

Boyles Law

ONLY law with an INVERSE relationship

Formula for molar mass

mm=dRT/P

Formula for Mole Fraction

Part mol/Total mol

Formula for Effusion or Diffusion

√ molar mass (heavy)/ molar mass (lighter)

Ideal Gases behave better at ______ temp and _____ pressure

Higher temp and Low pressure

London Dispersion

ALL molecules have LD

Dipole-Dipole

Polar Molecules and H+ Bonding have D-D

H+ Bonding

ONLY when Hydrogen is bonded to F, O, or N

Increasing boiling point

LD < D-D < H+ bonding < Ion-Dipole

Highest boiling point

element with the highest mass

Sublimation

Solid → Gas

Deposition

Gas → Solid

Volatile Liquid

One that readily evaporates

Strongest intermolecular forces

Compound with the Highest Hvap

Average molecular speed

Heaviest compound to lightest compound

How to find Average Atomic Mass

1. convert % (abundance) to decimals

2. multiply mass (amu) by abundance