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Chemical Terminology 1.0 Atomic Weight absolute atomic mass atomic weight 10-24 - 10-22 g 1 H-1 ≡ 1,6783 1/ C-12 12 ≡ 1,66053 .10-24 g 1/ C-12 12 ≡ 1u M .10-24 g Atom m = 1 12 Atom m (C −12) dimensionless number, weighted g according to the natural isotopic fraction mass defect Seite 1 1.1 Natural Isotopic Fractions natural isotopic fractions: H-1 99,9855 % H-2 0,0145 % H-3 traces O-16 99,759 % O-17 0,037 % O-18 0,204 % C-12 98,892 % C-13 1,080 % C-14 traces atomic t i weights: i ht H: 1,0079 O:15,999 C: 12,011 1.2 Atomic Mass relative atomic mass: M nuclide = molecular weight: m nuclide 1 m (C −12) 12 M dimension less number Not weighted according to the natural isotopic fraction Seite 2 molecule = m molecule 1 m (C −12) 12 dimension less number in covalent compounds 1.2.1 Examples: H2O CH4 SO2 O3 H2SO4 HCl HNO3 NaOH KOH 1,0079 . 2 1,0079 . 4 15,999 . 2 15,999 . 3 1,0079 . 2 1,0079 1,0079 1,0079 1,0079 + 15,999 + 12,011 + 32,06 = = = = + 15,999 . 4 + 32,06 = + 35,453 = + 15,999 . 3 + 14,007 = + 15,999 + 22,990 = + 15,999 + 39,098 = 18,0148 16,0426 64,058 47,997 98,0718 36,4609 63,0119 39,9969 56.1049 2.0 Moles 1 mol = NA particles 1 Mol He 1 Mol N2 1 Mol NaCl AVOGADRO's AVOGADRO s Number NA ≡ 4,003 g ≡ 14,007 x 2 ≡ 28,014 g ≡ 22,990 , + 35,453 , ≡ 58,443 g 12 g C ≡ 6,0221367 . 1023 C-atoms ≡ NA Seite 3 12 [g] 6,022 ⋅10 23 = 12u 1 1u = [g] 6,022 ⋅10 23 1C ≅ 2.1 Molar Solutions 1 1/ 10 5 5/ 8 molar NaCl solution molar KCN solution molar CuSO4 x 5H2O solution molar AgNO3 solution 3.0 Chemical Reactions Ö Ö Ö Ö Ö Ö photo h t reaction ti surface reaction (e.g. catalysis) polymer reaction complex reaction chain reaction redox reaction starting material Educts 1 O2 + 1 C Ö final material Products 1 CO2 stochiometrical yields Seite 4 3.1 Redox Reactions Na + 1/2 H2 Ö NaH H2 + 1/2 O2 Ö H 2O B + 3/2 H2 Ö BH3 Ca + 1/2 O2 Ö CaO Sr + H2 SrH2 S + O2 Ö SO2 Ö electron acceptance = reduction electron donation = oxidation 3.1.1 Examples: Fe / C oxidation oxidation agents 2 Fe C + + O2 Ö O2 Ö 3/ 2 Fe2O3 CO2 Silicate reduction reduction agents SiO2 + C Ö Seite 5 Si + CO2 3.2 Oxidation States Electric Charge K+, Ca2+ , Ca++, Fe3 +, Fe+++, Cl-, SO42-, SO4--, PO43-, PO4--Oxidation States f free elements l t monoatomic ions oxygen in peroxides e.g. H-O-O-H oxidation id ti state t t oxidation state oxidation state =0 = electric charge = -1 3.2.1 Oxidation States in inorganic compounds exception? yes find element 1 with ENmax oxidation state (element 1) = - valence find element 2 with ENmin oxidation state (element 2) = + valence more than 3 atom types yes sum over all oxidation states = total charge oxidation state (element 3) = difference Seite 6 3.2.2 Examples 1 +1 -1 +3 -1 +1 -2 +1 +5 -2 HCl FeCl3 H 2O H3PO4 +1 +1 +3 +1 +3 -1 -1 NaCl 0 C60 -1 -1 NaH BH3 NaBH4 +1 +1 +2 -3 +8/3 HCN Fe3O4 -1 H 2O 2 -2 3.2.3 Examples 2 different oxidation states of an atom +1 +7 -2 +4 -2 +2 +4 -2 KMnO4 MnO2 MnCO3 K permanganate manganese dioxide manganese carbonate +1 +6 +1 +4 +1 -2 -2 -2 H2SO4 H2SO3 H 2S sulphuric acid sulphurous acid hydrogen sulphide Seite 7 4.0 Separation Processes (1) • Adsorption • Centrifugation and Cyclones - density differences • Chromatography involves the separation of different dissolved substances as they travel through a material. The dissolved substances are separated based on their interaction with the stationary phase. • Crystallization • Decantation • Distillation - used for mixtures of liquids with different boiling points, or for a solid dissolved in a liquid. • Drying - removing liquid from a solid by vaporizing it 4.0 Separation Processes (2) • Evaporation • Extraction • Filtration. Mesh, bag and paper filters are used to remove large particulates suspended in fluids, eg. fly ash, while membrane processes including microfiltration, ultra filtration, nanofiltration, reverse osmosis osmosis, dialysis (biochemistry) utilizing synthetic membranes can separate micrometresised or smaller species. • Precipitation • Recrystallisation • Volatile Seite 8 Exercises 1. 2. 3. 4. 5. 6. 7. 8. What is the molecular weight of CuSO4 x 5 H2O ? How many atoms are in 1 g Uranium ? How much C must be oxidized to gain 10-6 t CO2 ? Explain the formation of SiO2 from Si and O2 using oxidation numbers ! What are the oxidation numbers in SiHCl3 ? How do you prepare a 0.25 m solution of sodium chloride ? What is decantation ? What is extraction ? Seite 9