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Chapter 22 Notes Solutions

Chapter 22 Notes Solutions. Section 1. Solutions. A mixture that appears the same throughout and is mixed at the HOMOGENOUS level SOLUTE=substance being dissolved SOLVENT=substance doing the dissolving Solutions can be liquids, gases, or SOLIDS ( example:alloys ). Soda? Steel?

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Chapter 22 Notes Solutions

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  1. Chapter 22 NotesSolutions Section 1

  2. Solutions • A mixture that appears the same throughout and is mixed at the HOMOGENOUS level • SOLUTE=substance being dissolved • SOLVENT=substance doing the dissolving • Solutions can be liquids, gases, or SOLIDS (example:alloys)

  3. Soda? • Steel? • Trail mix? • Salt water? • Italian salad dressing? Are these examples homogenous?

  4. How dissolving happens… • Water molecules are POLAR. What does polar mean? • Water molecules cluster around SOLID molecules, with their negative ends attracted to the positive ends of the solids • Water molecules then PULL the solid particles into solution • The moving WATER molecules and SOLID molecules spread out and mix evenly to form a SOLUTION • How do you think we mix solids to form alloys? • You must heat them!

  5. Rate of dissolving depends on: • Temperature • INCREASING the temp. of a solvent speeds up the movement of its particles • To make a gas dissolve more quickly in a liquid, COOL the liquid solvent and INCREASE the pressure of the gas • Stirring • Crystal Size • Dissolving occurs at the SURFACE of a solid. • Breaking a solid into pieces increases its SURFACE AREA

  6. Chapter 22 NotesSolubility and Concentration Section 2

  7. The amount of a substance that can dissolve in a solvent Solubility Depends on the nature of the SUBSTANCES Solubilities of two substances can be compared by DISSOLVING BOTH IN WATER

  8. Concentration Is expressed as percent by VOLUME of the solute • Has a large amount of solute in the solvent Concentrated Solution Dilute Solution Has a small amount of solute in the solvent

  9. There are 3types of Solutions

  10. 1. Saturated Solution • Contains all of the solute it can hold at a given temperature • As the temperature of a liquid solvent increases, the amount of solid solute that can dissolve in it INCREASES. • SOLUBILITY CURVE-line on a graph used to figure how much solute can dissolve at any temperature on the graph.

  11. Unsaturated Solution • Able to dissolve more solute at a given temperature

  12. Supersaturated Solution • Contains more solute than a saturated one at the same temperature. How could this happen? • Made by INCREASING temp. of a saturated solution, adding more solute, and lowering the temp back without RE-CRYSTALLIZING the solution • SUPERSATURATED SOLUTIONS will crystallize if disturbed • As it crystallizes, it gives off ENERGY and produces heat.

  13. Particles in Solution Section 3

  14. Ions: Particles with a charge • Nonelectrolytes • Substances that do not ionize (form charged particles) in water and cannot conduct electricity • Electrolytes • Compounds that form charged particles (ions) and conduct electricity in water

  15. How IONS form… • Molecules break apart in water causing atoms to become ions by taking on a charge (IONIZATION) • Then, an ionic solid separates into its positive and negative ions (DISSOCIATION)

  16. Effects of solute particles All solute particles-polar, nonpolar, electrolyte, and nonelectrolyte-affect the PHYSICAL properties of the solvent Adding a solute to a solvent LOWERS the freezing point because the added solute particles interfere with the formation of the orderly freezing pattern Adding a solute RAISES the boiling point because fewer solvent molecules can reach the surface and evaporate

  17. Dissolving without Water Section 4

  18. Do nonpolar molecules have a positive end and a negative end? NO!! So, how do they dissolve solutes?

  19. Nonpolar Dissolving • They are NOT attracted to the polar water molecules, so they do not DISSOLVE easily in water. • Example: NONPOLAR SOLUTES contain hydrocarbons • Large molecules of CARBON and hydrogen atoms • These atoms share ELECTRONS in an equal manner, so there is no positive or negative charge (nonpolar)

  20. Useful Nonpolar Molecules • Nonpolar solvents dissolve NONPOLAR solutes • Many nonpolar solvents are TOXIC (dangerous to touch or inhale) • Soap-used for washing because it has POLAR and NONPOLAR properties.

  21. Polarityand Vitamins • Vitamin A is NONPOLAR-dissolves in the FAT of some body cells. • B vitamins and vitamin C are POLAR-dissolve in the WATER in your body cells.

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