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Solutions and Their Properties Aim Solution1a – what is a solution?

This article explores the different types of solutions, solubility curves, factors affecting solubility, chemical effects on solubility, and solution strength. Learn about the properties and characteristics of solutions and how they interact with different substances.

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Solutions and Their Properties Aim Solution1a – what is a solution?

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  1. Solutions and Their PropertiesAim Solution1a – what is a solution?

  2. Solutions Review • Heterogeneous mixture • An unevenly distributed (clumpy) mixture • Solution • A homogeneous mixture • Mixtures that are evenly distributed • Parts of a solution • Solute - the dissolved substance in a solution • Solvent - the substance doing the dissolving in a solution

  3. Examples - Solutions • Gas in gas • air (various gases) • Gas in liquid • cola (water and CO2) • Effervescence – the bubbles you see are escaping gas molecules • Liquid in liquid • beer (alcohol and water) • Solid in liquid • saltwater, sugar water • Liquid in solid • mercury in gold amalgam for fillings • Solid in solid • alloys like steel and brass

  4. Solubility • Dissolution (dissolving) • the separation of solute particles by solvent particles • Ex: salt (ionic) and water (polar) • The attractive forces between solute and solvent particles are slightly broken • The different particles attract each other with forces of similar strength • Dissolving is based on polarities • “Like dissolve like” • polar solvents dissolve polar solutes • Nonpolar solvents dissolve non polar solutes

  5. Solution Types • Saturated solution • The amount of solute needed to just saturate a given amount of solvent • These are the points ON the solubility curve • Unsaturated solution • When more solute can still be dissolved in solution • The area below the solubility curve • Supersaturated solution • When more solute than normal is dissolved in solution • The area above the solubility curve

  6. Table G Solubility Curves • Curves represent the solubility • in grams, • of various substances (solids and gases), • in 100 g (100 mL) of water, • at varying temperatures

  7. Solubility Curves Relationships: Solids in the chart (KNO3, KI, NaCl, etc) As the temperature increases, the solubility of solids in solution increases (more can dissolve) Gases in the chart (SO2, NH3, and HCl) As the temperature increases, the solubility of solids in solution decreases (less can dissolve)

  8. Reading Table G - Solubility Curves What is the solubility of KI (potassium iodide) at 20oC? 145 g What is the difference in solubility for ammonia when the temperature changes from 10oC to 90oC? 60 g difference Which substance at 10oC has the lowest solubility in 100 g of water? KClO3 At what temp does KNO3 and NaNO3 have the same solubility? 71oC What is the solubility of KCl at 55oC in 200 g of water? 44 gram of KCl / 100 gram of water so 200 grams of water = 88 grams of KCl

  9. Soluble vs Insoluble substancesAim Solutions2b- How do I keep my cola fizzy?

  10. Factors Affecting Solubility • Various factors will increase (or decrease) the solubility of substances in a liquid solution • Surface Area • For solids • the amount of the solute’s surface that is exposed to solvent • By reducing the particle size (for example, by crushing) • dissolving rate increases • Example: sugar cube vs granulated sugar dissolving rates • For gases • There is no reducing the particle size for a gas • Therefore, surface does not affect gas solubility

  11. Factors Affecting Solubility Stirring For solids Increases solubility of the solid in solution Increases kinetic energy Exposes fresh solvent to solute For gases Decreases solubility of the gases in solution Increases kinetic energy Gases more easily escape solution

  12. Factors Affecting Solubility Pressure For solids Does not affect the solubility You can’t “squeeze” a solid or a liquid For gases Increases the solubility of the gases in solution Squeezes a gas into the liquid Gases go into solution or are held in solution more

  13. Factors Affecting Solubility Temperature For solids As the temperature increases The solubility increases For gases As the temperature increases The solubility decreases

  14. Application of what you just learned… What factors will keep your cola fizzy? Lower the temperature Don’t stir or shake it Increase gas pressure Surface area – nothing you can do! What factors will dissolve your sugar into your coffee faster? Raise the temperature Stir or shake it Crush the solid solute so there is more surface area In terms of pressure – nothing you can do!

  15. Chemical Effects on Solubility Different substances have different solubilities Their chemical nature does not always allow them to exist in solution For example AgNO3 – highly soluble in water AgCl – insoluble in water (or nearly so) See Table F for Solubility Guidelines for Aqueous Solutions

  16. See Table F for Solubility Guidelines for Aqueous Solutions • Right side of chart • Insoluble substances with exceptions • Left side of chart • Soluble substances with exceptions

  17. Reading Table F

  18. Nerd (def): (noun) an individual persecuted for their superior skills or intellect, most often by people who fear and envy them… Concentration Strength Aim Solutions 3c – how strong is my ice tea?

  19. Solution Strength or Concentration • Concentration • The strength of a solution • A measure of the quantity of solute in a given solvent • Concentrated • high levels of solute per solvent • Dilute – low levels of solute per solvent

  20. Molarity A measure of concentration in moles per liter (M) Molarity is the number of moles of solute dissolved in 1 liter of solution Concentration formula: molarity = moles of solute liters of solution Mr. Foley pours 2.80 moles of salt into 2.00 liters of solution. What is the concentration of the salt solution? M = moles liter x M = 2.80 moles 2.00 L x M = 2.80 moles = 1.40 M solution of salt 2.00 L

  21. Calculating the molarity of solutions • A student dissolves 2.00 moles of NaCl in 8.00 L of solution. What is the molarity or concentration of the solution? M = moles liter 2.00 M NaCl = x moles 8.00 L x = 16.0 moles of NaCl • Mr. Foley adds 2.80 moles of salt to another container, making a 5.20 molar solution. How much solution did he make? M = moles liter 5.20 M = 2.80 moles x L x L = 2.80 moles = 0.538 L of solution 5.20 M

  22. Parts per million Measures very dilute solution Some substances are toxic / carcinogenic in very small amounts Formula on Table T ppm = mass in grams of solute x 106 mass of solution Examples Carbon monoxide 100 ppm can cause health issues 1 balloon in a gym’s worth of air! Arsenic 0.05 ppm is dangerous 1 drop in a gallon container!

  23. Calculating parts per million in very dilute solutions Examples A given toxin has a concentration of 2.20 grams per 10,000 grams of solution. If only 200.0 ppm is required to kill you, will you get sick if you drink the water? ppm of solute = mass of solute x 106 mass of solution ppm of solute = 2.20 g of poison x 106 10,000 g of solution ppm of solute = 220 ppm you are over the limit of toxin allowed!

  24. Solution Concentration - ppm Ex: Dr. Phaux Lee, a mad scientist hidden within the bowels of Hauppauge HS, has added 200.0 grams of his truth serum to a teacher’s room Poland spring water container with 20,000 grams of water. What is the concentration in parts per million? ppm = mass of solute x 106 mass of solution ppm = 200.0 grams of serum x 106 20,000 g of water + 200 g of serum ppm = 200.0 grams of serum x 1,000,000 20,200 g of solution ppm = 990 ppm – that’s a lot of truth serum!

  25. Other Effects of Solute in solution Colligative properties • Boiling and freezing points are affected by solutes dissolved in a solution • Dependent on the number of particles or ions in the solution • Examples: how many different particles dissolve in: • Glucose (C6H12O6)? • 1 only – glucose doesn’t break up • Sodium chloride (NaCl)? • 2 particles – a Na+ ion and a Cl- ion • Rock salt (CaCl2) • 3 particles – 1x Ca+2 ion and 2x Cl- ions

  26. Solute Effects on Boiling Point Solute particles in solution bond with solvent particles This lowers the vapor pressure of the solvent Therefore RAISING the boiling point Example: table salt (NaCl) in water for cooking pasta 2.00 moles of NaCl (117 g) are added to 1.00 kg of water. What is the new boiling point? NaCl divides into Na+ ions and Cl- ions, for a total of 4 moles of solute Boiling point = 100oC + (4 x 0.52oC) = 102.04oC

  27. Solute Effects on Freezing Point Solute particles in solution bond with solvent particles and inhibit crystal formation as the temperature drops This lowers the freezing point of the solvent Therefore lowering the freezing point Example: Rock salt (CaCl2) placed on your driveway 2.00 moles of CaCl2 (111 g) are added to 1.00 kg of water. What is the new freezing point? CaCl2 divides into Ca+2 ions and Cl- ions, for a total of 6 moles of solute Freezing point = 0oC - (6 x 1.86oC) = -11.2oC or 11.84oF this is the temp the air must get to in order to freeze the water

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