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Chemical Classification: Composition :Organic Chemicals / Hydrocarbons Inorganic Chemicals : Elements Salts Organometallics Use:PesiticidesSolvents HerbicidesDyes.

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Presentation on theme: "Chemical Classification: Composition :Organic Chemicals / Hydrocarbons Inorganic Chemicals : Elements Salts Organometallics Use:PesiticidesSolvents HerbicidesDyes."— Presentation transcript:

1 Chemical Classification: Composition :Organic Chemicals / Hydrocarbons Inorganic Chemicals : Elements Salts Organometallics Use:PesiticidesSolvents HerbicidesDyes Flame retardantsagro-chemicals

2 Nomenclature Common name : Dioxin Compositional Formula : C 12 O 2 H 4 C l4 Structural Formula : Systematic Name Chemical Abstract Serial number : CAS number

3 How do you know in what physical shape the chemical is? PhasesProperties SolidMelting Point LiquidBoiling Point vapour (gas phase)Dissociation Constant dissolvedSolubility dissociated speciation

4 Expressing the Quantity of a chemical substance Solids: Units: grams, moles moles = grams/molecular weight How do you find the molecular weight? : Periodic Table

5 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

6 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

7 Gases: pressure Units of pressure : N/m 2 = Pa 1 Atm = Pa 1 Torr = 1 mm hg = 133 Pa

8 1 L Container with Cl2 gas at a pressure of 100 mm Hg and a temperature of 25 o C How many moles and grams of Cl2 do I have in that container? p.V = n.R.T p = Conc. R.T R = J/mol/K T = = 298 p = 100 mm * 133 = Pa Conc = 13300/2478 = 5.36 mol/m3 1L container = m3 = 5.36 mmol = 5.36 *10 -3 * 71 = 0.38 gram

9 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

10 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

11 K sw = CsCs CwCw K OC = C OC CwCw Kow Koc K OC = 0.41.K ow Sediment-Water Partition coefficient Units: L/kg dry sediments Units: L/kg organic carbon Units of 0.41 are L/kg organic carbon Organic Carbon-Water Partition coefficient C S : Concentration in sediment (g/kg dry) ; C OC : Concentration in organic carbon (g/kg) C W : Concentration in water (g/L) ; K OW : Ocatnol-Water Partition Coefficient

12 K sw = CSCS CWCW K OC = C OC CwCw Kow Koc K oc = 0.41.K ow Sediment-Water Partition coefficient K SW (L/kg dry sediment) =  OC.K OC = 0.41.K ow Organic Carbon-Water Partition coefficient K OC (L/kg Organic carbon) C S : Concentration in sediment (g/kg dry) C OC : Concentration in organic carbon (g/kg) C W : Concentration in water (g/L) K OW : Ocatnol-Water Partition Coefficient

13 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

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16 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.


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