Chemistry week 2 notes
Chemistry week 2 notes chem 132
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This 8 page Class Notes was uploaded by Ariel Kamen on Sunday February 7, 2016. The Class Notes belongs to chem 132 at Towson University taught by Sarah T. Stokes in Winter 2016. Since its upload, it has received 19 views. For similar materials see general chemistry lecture 2 in Chemistry at Towson University.
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Date Created: 02/07/16
2/4/16 CH4 HCl H2O C8H18 H2O Things to find 16 36 18 114 18 Molecular weight g/mol NP P P NP P Polarity dispersion disp./dd disp./dd/H disp. disp/dd/H IMF bonding bonding lowest middle highest ? ? Boiling point 2 variables cannot determine B.P. Skip 12.4 12.5 Chapter • ALL SOLIDS 4 types of crystals: Ionic ionic bonding, brittle, hard (melting + boiling point) = high melting point * doesn't conduct heat or electricity * Molecular covalent bonds, within a molecule, IMF’s between molecules low melting point & low boiling point soft does not conduct electricity/heat Covalent all covalent bonds hard high melting point do not conduct electricity/heat Metallic metallic bonds soft to hard low to high conducts heat and electricity 2/9/16 Tc critical temperature Pc critical pressure Tc above this temperature no liquid can form no matter how great the pressure Pc at critical temperature, pressure required to condense gas Liquid/solid equilibrium (delta)Hfus —> energy required to melt 1 mole of the solid (delta)Hvap vs (delta)Hfus = (delta)Hvap > (delta)Hfus H2O (delta)Hfus 6.01 KJ/mol (solid—> liquid) + (delta)Hvap 40.79 KJ/mol (liquid —> gas) ____________________________ Chapter 13 Solutions: unsaturated some solute dissolved but we haven’t hit the maximum saturated maximum amount of solute that will dissolve in a specific quality of solvent at a given temp. supersaturated (unstable) raise the temp and get more solute dissolved, cool back down, temporarily more solute is dissolved than a saturated solution solute: substance in lesser amount solvent: substance in greater amount solution: solute and solvent Concentration Units Molarity, M, moles solute/ L solution , mol/L % mass % m/m mass of solute/ mass of solution x 100 2/11/16 Practice 13.3 find molality of 5.86 M aqueous ethanol solution (C2H5OH, ethanol) density of solution is 0.927 g/mL molality = mol solute (eth) / kg solvent (H2O) 5.86 mol ethanol / 1 L solution * 46.07 g eth / 1 mol eth = 270 eth 1000 mL of solution * 0.927 g solution / 1 mL solution = 927 g solution 270 g solute + g solvent _______________ 927 g solution 927 270 = 657 g solvent = 5.86 mol eth ____________ 0.657 kg H2O * M: ____ / L solution m: ____ / kg solvent Find molality of 44.6% m/m aqueous solution of NaCl m = mol of NaCl / kg of H2O %m/m = 100 x mass of NaCl / mass of solution * assume 100 g of solution 44.6 g NaCl 55.4 g H2O 44.6 g NaCl * 1 mol NaCl / 58.44 g NaCl = 0.763 mol NaCl m = 0.763 mol NaCl / 0.0554 kg H2O = 13.8 m Temperature and Solubility solids & gases • as temperature goes up; solubility of solids go up • as temperature goes up; solubility of gases Pressure and Solubility • as pressure goes up; solubility of gases goes up C = (1.3 x 10 ^ 3 mol / L * atm) 0.22 atm = 2.9 x 10 ^ 4 mol / L Colligative Properties • vapor pressure lowering • freezing point depression • boiling point elevation • osmotic pressure * Properties change based number of solute particles not on identity of these particles Raoulth’s Law nonvolatile solute: solid in liquid volatile solute: liquids in liquids 8.24 g of urea (NH2)2CO in 212 mL of H2O find v.p. (25 degrees C, DH2O 1.00 g / mL, 42.18 mm Hg) v.p. of pure water. Xh2o = nH2O / nT = nH2O / nH2O + n urea 82.4 g (NH2)2CO * 1 mol / 60.07 g (NH2)2CO = 1.37 mol urea 212 mL H2O * 1 g / 1 mL = 212 g H2O……212 H2O * 1 mol H2O / 18.02 g H2O = 11.8 mol H2O XH2O = 11.8 / 11.8 + 1.37 = 0.9 P = 0.9(XH2O) * 42.18 mm Hg (pH2O) P = 37.7 mm Hg
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