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Unformatted text preview: Chapter 11 – PROPERTIES OF SOLUTIONS 11.1 Solution Composition: a. Overview and Terms: i- A Solution is a homogeneous mixture that consists of solute and solvent (the latter is one that is present in the largest quantity). ii- An aqueous solution (aq) has water as the solvent. iii- Concentrated solution- contains a large amount of dissolved solute. iv- Dilute solution– contains small amount of dissolved solute. v- Saturated solution– contains the maximum amount of dissolved solute that is normally possible at a particular temperature. vi- Unsaturated solution- a solution that can dissolve (hold) more solute. vii- Supersaturated solution – contains more dissolved solute than it normally does to give a saturated solution at a particular temperature. b. Units of Concentration: How much solute is in a solution? 1. Mass Percent % = Mass of solute_ x 100% Mass of solution 2. Mole fraction ( X i ) = Mole of a component __________ Total moles of components in solution 3. Molality (m) = M oles of solute Kg of solvent 4. Molarity (M) = Moles of solute Liters of solution 5. Parts per Million (PPM) = mg of solute Liter of solution = g solute x 10 6 g solution * Mass %, Mole Fraction, Molality INDEPENDENT of temperature * Molarity, PPM dependent on temperature because as the solution temp changes, the solution volume may change 1 Example 11.1A- Solution Components Identify the solvent and solutes in the following solution. (a) Dry air contains about 78.1% nitrogen, 21.0% oxygen, 0.9% argon, and trace amounts of other gases. (b) Natural gas contains 97% methane (CH 4 ), 1.5% ethane (C 2 H 6 ), 1% CO 2 , and 0.5% nitrogen gases. (c) Rubbing alcohol contains 70% isopropyl alcohol and 30% water. Example 11.1B- Units of Concentration a. A solution is prepared by dissolving 2.275 g of NaOH in enough water to make a 200.0 mL solution. Calculate the molarity of the solution. b. Calculate the mass percent of the solute in a solution containing 19.5 g NH 4 Cl in 485 g of water. What is the molality of the solution? c. A solution is prepared by mixing 16.0 g of CH 3 OH and 50.0 g of water. (i) What is the mass percent of methanol in the solution? (ii) what is the mole fraction of each component in the solution? (iii) If the density of solution is 0.955 g/mL, what is the molarity and molality of CH 3 OH, respectively, in the solution?...
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This note was uploaded on 06/20/2011 for the course CHEM 111A taught by Professor Hockings during the Fall '08 term at Washington University in St. Louis.
- Fall '08