1 / 34

Solutions

Solutions. Water’s Unique Properties. There are strong forces of attraction between molecules of water. Hydrogen bonds Water is a polar molecule Water is amphoteric (can act as both acid & base) Water exists as a liquid over a wide temp range .

kevyn
Download Presentation

Solutions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solutions

  2. Water’s Unique Properties • There are strong forces of attraction between molecules of water. Hydrogen bonds • Water is a polar molecule • Water is amphoteric (can act as both acid & base) • Water exists as a liquid over a wide temp range. • Liquid water changes temperature slowly. High specific heat • Liquid water can dissolve a variety of compounds. • Water expands when it freezes.

  3. Attraction Between Molecules • There are strong forces of attraction between molecules of water. • Hydrogen bonds • Result in many distinctive properties

  4. Liquid state Exists in liquid state over wide range of temperatures: 32° F to 212° F This is important because most biological processes require liquid water.

  5. Unique Role of Water in Biological Systems It makes up about 70% of the human body • It takes up about 71% of the Earth’s surface.

  6. Key Role in Biological Systems • Water is critical to virtually all cellular function • Metabolism • Diffusion • Osmosis • Transport • Reproduction • Lubricant • Volume • Cellular respiration: C6H12O6 + O2 → CO2 + H2O + energy • Photosynthesis: CO2 + H2O + sunlight → C6H12O6 + O2

  7. High Heat Capacity • Water warms & cools slower than surrounding land • Helps moderate earth’s climate

  8. Universal Solvent: • Water can dissolve many substances. • Carry nutrients • flush wastes • distribute particles • facilitate other cycles • Unfortunately, it can become polluted by water-soluble wastes & transport wastes thru ecosystem

  9. Expands When Frozen • Ice has a lower density than liquid water. Thus, ice floats on water. • One of the only exceptions to thermal expansion

  10. Surface tension • Surface behaves like an elastic membrane • Cohesion– water molecules stick to each other

  11. Capillary action Long narrow columns of water rise through roots to leaves Adhesion– water molecules stick to other surface

  12. What are solutions? Solute • Homogeneous mixtures containing 2 or more substances called the solute and the solvent. Solvent • When you look at a solution it is impossible to tell the solute from the solvent

  13. Solutions • Solute- what is being dissolved • Solvent- the dissolving medium (causes the dissolving) • Solution- the resulting homogeneous mixture • Aqueous Solution - water is solvent • Dilution – adding more solvent = less concentrated

  14. Universal Solvent • Water is the most common solvent among liquid solutions • H2O is polar, having a slightly positive charge on the hydrogen end and negative charge on the oxygen end. • Because water is polar it dissolve other polar and ionic compounds

  15. Dissolution or Solvation of Solid Solute = Dissolving Happens only on the surface Water molecules surround, attract, and pull ions or molecules into solution

  16. Like dissolves Like • Polar substances dissolve polar • Nonpolar substances dissolve nonpolar • Water is polar…which of the above will dissolve in H2O Mineral Oil Isopropyl Alcohol Glucose

  17. Solubility • Solubility is maximum amount of solute that will dissolve in solvent at a set of condition • Soluble - A substance that dissolves in a solvent ex. Salt and water • Insoluble - A substance that does not dissolve ex. Sand and water • Miscible – 2 liquids that are soluble • Ex. Alcohol and water • Immiscible – 2 liquids that aren’t soluble • Oil and Water

  18. Factors Affecting Solubility& Rate of Dissolution (Dissolving) • Nature of Solute / Solvent. - Like dissolves like • Polar dissolves polar; nonpolar dissolves nonpolar • 2. Temperature - affects velocity of particles • 3. Pressure • 4. Agitation = Stirring – disperses particles • Surface Area: crushing increases surface area on which dissolving can occur Sugar cubes vs Granulated sugar

  19. Factors Affecting Solubility& Rate of Dissolution (Dissolving) ↑ ↓ N/A ↑ ↑ ↓ N/A – can’t crush a gas! ↑

  20. General Solubility Rules • Use STAAR Chart to determine Which Ionic compounds are soluble and insoluble • NaNO3 • AgCl • Be3(PO4)2 • Na3PO4 soluble insoluble insoluble soluble

  21. Types of Solutions • Electrolytes – ionic compounds dissolve into ions conducts electric current the more ions → stronger current • Nonelectrolytes – molecular compounds: stay molecules in solution no ions → do not conduct current

  22. Nonelectrolyte Strong electrolyte Weak electrolyte

  23. Electrolytes in the Body • Carry messages to and from the brain as electrical signals • Maintain cellular function with the correct concentrations electrolytes

  24. Types of Solutions • Saturated Solution: Full • Unsaturated Solution: not full • Supersaturated Solution: overly Full, crystals will form when disturbed

  25. Saturated Solution • Contains the maximum amount of dissolved solute for a given amount of solute at at specific temperature • No more will dissolve • Will be a point on the line of a Solubility Graph Ex. NaClO3 at 40°

  26. Unsaturated solution • contains less dissolved solute for a given temperature and pressure than a saturated solution • More can be dissolved • Will be a point under the line on graph Ex. NaClO3 at 40°

  27. Supersaturated solution • contains more dissolved solute than a saturated solution at the same temperature • Contains more than it should • Will precipitate if disturbed • Will be a point above the line Ex. NaClO3 at 40°

  28. Saturated solution to supersaturated solution • http://www.youtube.com/watch?NR=1&v=1y3bKIOkcmk&feature=fvwp

  29. Solubility Graph Determine type of solution: 30 grams of NaClat 10°C Unsaturated 30 grams of K2Cr2O7 at 50°C Saturated 50 grams of KCl at 40°C Supersaturated

  30. moles solute ( M ) = Molarity Liters of solution Concentration of Solute The amount of solute in a solution is given by itsconcentration. EX: A liter of solution containing 0.1 mole of solute is a 0.1 M solution

  31. A 100.5ml intravenous, IV, solution contains 5.10g of glucose (C6H12O6). What is the molarity of this solution? 0.0283 Moles of solute = Molarity = Mass of solute = 5.10g C6H12O6 Volume of solution = 100.5ml Molarity = ? Liters of solution .1005 1st – calculate the # of moles 1 mole C6H12O6 5.10g C6H12O6 = 0.0283 mol C6H12O6 180.16g C6H12O6 2nd – convert milliliters into liters (1000 ml = 1 L) 0.1005 100.5ml = ______________L 3rd – use formula to solve = 0.282M

  32. Dilution Quite often, however, solutions are prepared by diluting a more concentrated solution. For example, if you needed a one molar solution you could start with a six molar solution and dilute it. The number of moles of solute stays the same. You have simply increased the amount of solvent in the solution Because total # of moles of solute doesnotchange during dilution: moles in stock solution = moles after dilution, so: Molaritydecreases as Volume increases V1M1= V2M2

  33. What volume of a 3.0 M KI stock solution would you use to make a 0.50 L of a 1.5M KI solution??? 1st : Make a list M1 = 3.0 M V1 = ? V2 = 0.50 L M2 = 1.5 M Then plug into formula: V1M1 = V2M2 V1 (3.0) = 0.50(1.5) And solve for V1 = 0.50(1.5) 3.0 = 0.25 L

More Related