NYA Equations

STOICHIOMETRY
number of mole (n)    
n =   m
molar mass
number of particle = mole x Avogadro number (mol-1)number particle = n x NA     (NA = 6.022x1023 mol-1)
mass%
mass%(A) =  100% x  mass of A in the sample
total mass of the sample
GASES
Ideal gas lawP V = n R T
TYPES OF CHEMICAL REACTIONS and Solution Stoichiometry
molarity (M in mol.L-1)
M =   nsolute
Vsolution
att: FOR DILUTION ONLY (the number of mole is constant)c1V1 = c2V2
ATOMIC STRUCTURE AND PERIODICITY
Relation between the speed of light c, the wavelength λ and the frequency νc = λ ν
The quantum of energy absorbed or emitted by an atom (h = Planck constant)ΔEatom = h ν                       ΔE can either be positive or negative
Energy of a photonEphoton = h ν                 ΔEphoton > 0 (always)
The photoelectric effect (Einstein)
Ekinetic = ½ mev2 = h ν - h νo         me: mass of the electron,   v: speed of the electron,
νo: threshold frequency to extract the electron from the surface.
de Broglie wavelength
(wavelength of a moving particle)
λparticle =   h
m v
             m: mass,    v: speed of the moving particle
The Bohr model of an atom
Eatom = (−2.178×10−18 J)  Z 2
n 2
             Z atomic number (number of protons)
            n main quantum number (energy level)
Change of energy of an atom ΔE atom = E final − E initial
Heisenberg uncertainty principle
Δx · Δ(m v) ≥   h
4 π
            Δx: uncertainty on the position,
            Δ(m v): uncertainty on the impulsion (mass × speed)
BONDING GENERAL CONCEPTS
Coulomb's law: Energy of interaction between a pair of ions
E = (2.31x10−19 J·nm)  Q1Q2
r
         (no need to memorize this equation, just understand.)
Bond energy and enthalpy ΔH reaction = ΣnDbonds broken − ΣnDbonds formed
Lewis formal charge (FC ) calculation
FC = nvalence electron in the free atom  − nelectron in lone pair  −  nelectron shared
2
COVALENT BONDING
Bond order (BO ) calculation
BO =   n bonding electron − n antibonding electrons
2
THERMOCHEMISTRY
Enthalpy 'H'  of a reactionΔH reaction = ΣΔH products − ΣΔH reactants
Specific Heat capacity c
c =   heat absorbed
ΔT x mass (g)
 
 
              where:   ΔT = Tfinal − Tinitial
Heat q  transfered by a reaction q = m × c × ΔT
Conservation of the energy qsystem + qsurrounding = 0
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