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Chemical Classification : Composition : Organic Chemicals / Hydrocarbons

Chemical Classification : Composition : Organic Chemicals / Hydrocarbons Inorganic Chemicals : Elements Salts Organometallics Use : Pesiticides Solvents Herbicides Dyes Flame retardants agro-chemicals. Nomenclature Common name : Dioxin

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Chemical Classification : Composition : Organic Chemicals / Hydrocarbons

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  1. Chemical Classification: Composition : Organic Chemicals / Hydrocarbons Inorganic Chemicals : Elements Salts Organometallics Use: Pesiticides Solvents Herbicides Dyes Flame retardants agro-chemicals

  2. Nomenclature Common name : Dioxin Compositional Formula : C12O2H4Cl4 Structural Formula : Systematic Name Chemical Abstract Serial number : CAS number

  3. How do you know in what physical shape the chemical is? PhasesProperties Solid Melting Point Liquid Boiling Point vapour (gas phase) Dissociation Constant dissolved Solubility 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/m2 = Pa 1 Atm = 101325 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 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

  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. Cs COC KOC = ------- Ksw = ------- Cw Cw Sediment-Water Partition coefficient Units: L/kg dry sediments Organic Carbon-Water Partition coefficient Units: L/kg organic carbon Koc KOC = 0.41.Kow Units of 0.41 are L/kg organic carbon Kow 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

  12. CS COC KOC = ------- Ksw = ------- CW Cw Sediment-Water Partition coefficient KSW (L/kg dry sediment) = OC.KOC Organic Carbon-Water Partition coefficient KOC (L/kg Organic carbon) = 0.41.Kow 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 : Ocatnol-Water Partition Coefficient Kow

  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

  14. 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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