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Chemical Classification:
Composition :
Organic Chemicals / Hydrocarbons
Inorganic Chemicals : Elements
Salts
Organometallics
Use:
Pesiticides
Solvents
Herbicides
Dyes
Flame retardants
agro-chemicals
Nomenclature
Common name : Dioxin
Compositional Formula : C12O2H4Cl4
Structural Formula :
Systematic Name
Chemical Abstract Serial number : CAS number
How do you know in what physical shape the chemical is?
Phases
Properties
Solid
Melting Point
Liquid
Boiling Point
vapour (gas phase)
Dissociation Constant
dissolved
Solubility
dissociated
speciation
Expressing the Quantity of a chemical substance
Solids:
Units: grams, moles
moles = grams/molecular weight
How do you find the molecular weight? :
Periodic Table
e.g. 100 gram kitchen salt, how many moles of salt
do I have?
Na: 23 + Cl: 35.5 = NaCl = 58.5
moles = 100/58.5 = 1.71 moles
1 mole of NaCl = 58.5 gram
Liquids:
Units: liters
e.g. alcohol : 1 liter
To convert from liters to grams or moles :
Density (kg/L)
e.g. Density of Alcohol = 0.82 kg/L
Gases:
pressure
Units of pressure : N/m2 = Pa
1 Atm = 101325 Pa
1 Torr = 1 mm hg = 133 Pa
1 L Container with Cl2 gas at a pressure of 100 mm Hg
and a temperature of 25o C
How many moles and grams of Cl2 do I have in that
container?
p.V = n.R.T
p = Conc. R.T
R = 8.314 J/mol/K
T = 273 + 25 = 298
p = 100 mm * 133 = 13300 Pa
Conc = 13300/2478 = 5.36 mol/m3
1L container = 0.001 m3 = 5.36 mmol = 5.36 *10-3* 71 =
0.38 gram
In solution:
Concentrations
Molarity M
grams/liter
ppm, ppb, ppt etc.
Environmental Literature:
ppth = 1 mg/mL = 1 g/L
ppm = 1 g/mL = 1 mg/L
ppb = 1 ng/mL = 1 g/L
ppt = 1 pg/mL = 1 ng/L
Environmentally Relevant Chemical Properties
Solubility
Vapour pressure
Henry Law Constant
Dimensionless Air-water partition coefficient
Octanol-Water Partition Coefficient
Octanol-Air Partition Coefficient
Organic Carbon - Water Partition Coefficient
Sediment-Water Partition Coefficient
Sediment-Water Partition coefficient
Cs
Ksw = ------Cw
Units: L/kg dry sediments
Organic Carbon-Water Partition coefficient
COC
KOC = ------Cw
Units: L/kg organic carbon
Koc
KOC = 0.41.Kow
Kow
Units of 0.41 are L/kg
organic carbon
CS : Concentration in sediment (g/kg dry) ; COC : Concentration in organic carbon (g/kg)
CW : Concentration in water (g/L) ; KOW : Ocatnol-Water Partition Coefficient
Sediment-Water Partition coefficient KSW
(L/kg dry sediment)
CS =  .K
Ksw = ------OC OC
CW
Organic Carbon-Water Partition coefficient KOC
(L/kg Organic carbon)
COC
KOC = ------- = 0.41.Kow
Cw
Koc
Koc = 0.41.Kow
CS : Concentration in sediment (g/kg dry)
COC : Concentration in organic carbon (g/kg)
CW : Concentration in water (g/L)
Kow
KOW : Ocatnol-Water Partition Coefficient
Persistence
• Rate Constant
• Half-life
• Residence time
•Residence Time = 1/rate constant
•Half-Life time = 0.693/rate constant
•Half-life = 0.693*Residence Time
Bioaccumulation
BioConcentration Factor (BCF)

BioMagnification Factor (BMF)

BioAccumulation Factor (BAF)

Octanol-Water Partition Coefficient
(Kow)

Toxicity
LC50
LD50
EC50
NOAEC
LOAEC
LC50
(Lethal Concentration):
Definition
Is the concentration (in water, air) which when
administered to a number of individuals of a certain
species of organisms over a specified period of time
causes death to 50% of the individuals included in the test.