Chem 1100 Lecture 13Outline of Last Lecture I. WaterII. ElectronegativityIII. Hydrogen BondsOutline of Current Lecture I. Water ContinuedII. Water as a SolventCurrent LectureI. Water Continueda. 2.6% of water is fresh water. 97.4% of water is salt water.b. To make salt water into drinking water is a very expensive process.c. Fresh water comes from lakes/rivers (0.01%) & glaciers/ice caps (2.59%)d. Aquifers: water trapped in sand/gravel. It’s relatively cheap to pump out of the ground and is usually not contaminated. e. If these aquifers do get contaminated then it ruins all of the water forever. Seawater can contaminate it and soluble materials can contaminate it as well. f. The aquifers do replenish themselves naturally but we are pulling out the water faster than it can replenish it. g. It replenishes itself about 4 inches a year. But when we are farming we take about 4 ft. out a year.II. Water as a Solventa. Solvent is something that dissolves other compounds.i. Solute is the stuff being dissolvedii. Solution = solvent + soluteiii. Water is the solvent in aqueous solutionsiv. Saline solution: the solvent is water and the solute is NaClv. Water dissolves many things – “universal solvent”b. How pure is water?i. 100% pure water is wishful thinkingii. Contaminants (ionic compounds dissolve in water)c. Concentrationi. Amount of solute per volume of solventii. Percent by volume These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. (10% ethanol gasoline) – I gal = 0.1 gal ethanol + 0.9 gal gasiii. Percent by mass1. 1% NaCl = 1g NaCl in 100 mL H20iv. Parts per million (ppm)1. Grams per million grams (mg per L)v. Parts per billion 1. Grams per billion grams (ug per L)vi. Molarity (M) – moles per liter1. Convert g to mol2. Convert volume to L3. Divide mol by Lvii. EXAMPLE: = 1.14 Mviii. EXAMPLE: ix. EXAMPLE FIND GRAMS FROM MOLS ABOVE^^^x. EXAMPLE: d. Molar Concentrationi. M = moles solute/ L solutionii. I give you two and you have to calculate the thirdiii. You may need to convert grams to moles or volume to LIII. Electrolytea. Conducts electricity when dissolved in water.b. Non-electrolytes: do not conduct electricity when dissolved in water.c. Conductivity: due to ions in solutionsd. More ions = better conduction e. Electrolyte – ionizedf. NaCl + H20 Na+ + Cl-
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