MCAT General Chemistry - Unit 1

Pico

10^-12

Nano

10^-9

Micro

10^-6

Mili

10^-3

Centi

10^-2

Kilo

10³

Mega

10^6

Giga

10^9

Molarity (M)

moles of solute per litre of solvent

One Angstrom is equal to….

10^(-10)m

Atomic radii lengths are about _________ Å

1-3 Å

Density (p)

mass/volume

Units of Density

Kg/m³ or g/cm³

Polyatomic Ions are

a bonded single unit compound that carries a charge

Ammonium

NH4+

Hydronium

H3O+

Acetate

CH3CO2-

Bicarbonate

HCO3-

Cyanide

CN-

Hydroxide

OH-

Nitrate

NO3-

Nitrite

NO2-

Perchlorate

ClO4-

Carbonate

CO3^(-2)

sulfate

SO4^(2-)

Sulfite

SO3^(2-)

Phosphate

PO4^(3-)

What is a mole?

A particular number of things

Avogadros number (N_A)

6.02 × 10^(23)

How to find molecules using moles and N_A?

#moles x N_A = #molecules

How to find # moles?

Mass in grams / molecular weight amu

Percent Composition

Found best using empirical formula

Percent composition for a particular atom

Take the mass of the molecule divided by the mass of the entire compound to find percentage of that molecule in the compound

Mole fraction

#moles of a solute / #litres of solution

Stoichiometric relations using balanced equations

Using the balanced equation, find how much is made from what is consumed → reactions to products and vice versa

the equation tells us the ratios, we simply need to determine how much of a reactant in moles it is to compare to given ratios to find the product moles

The limiting reagent

The reactant that will run out first which inhibits the reaction from going further

Oxidation states

The hypothetical charge an atom would have if it were ionic

Oxidation state rules

Neutral = 0

Group 1 = +1

Group 2 = +2

Fluorine = -1

Hydrogen = +1 with all except metals

Oxygen = -2

Halogens = -1

Peroxide oxygens(H2O2, N2O2) = -1

if ion is charged already(ex. NO3-), then the charge of the atoms must equal that total charge(not neutral, but equals the charge on the atom ex. -1)