Pol, Sol, Acids & Bases


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Pol, Sol, Acids & Bases

  1. 1. Chemistry 1 Unit 6 Notes - Polarity, Solubility, Acids and Bases
  2. 2. Polar or Nonpolar <ul><li>It is important to know if substances are polar or nonpolar </li></ul><ul><ul><li>Because it tells you whether or not they will dissolve in each other </li></ul></ul><ul><li>The rule is that “like dissolves like” </li></ul><ul><ul><li>Polar substances dissolve polar substances </li></ul></ul><ul><ul><li>Nonpolar substances dissolve non-polar substances </li></ul></ul>
  3. 3. Polar or Non-Polar (cont.) <ul><li>Polar means… </li></ul><ul><ul><li>A substance has a positive and negative end </li></ul></ul><ul><ul><ul><li>Therefore, all ionic compounds are polar! </li></ul></ul></ul><ul><li>Non-polar means… </li></ul><ul><ul><li>A substance does not have a positive and negative end </li></ul></ul>
  4. 4. Polar or Non-Polar (cont.) <ul><li>An easy way to check for polarity is to check for symmetry </li></ul><ul><ul><li>If a molecule is symmetric… </li></ul></ul><ul><ul><ul><li>It is non-polar </li></ul></ul></ul><ul><ul><li>If a molecule is not symmetric… </li></ul></ul><ul><ul><ul><li>It is polar </li></ul></ul></ul>Let’s see some examples on the next slide.
  5. 5. Polar or Non-Polar (cont.) <ul><li>Is this molecule symmetric? </li></ul><ul><ul><li>CH 4 </li></ul></ul><ul><li>It is symmetric, therefore it is… </li></ul><ul><ul><li>Non-polar </li></ul></ul>
  6. 6. Polar or Non-Polar (cont.) <ul><li>Is this molecule symmetric? </li></ul><ul><ul><li>H 2 O </li></ul></ul><ul><li>It is not symmetric, therefore it is… </li></ul><ul><ul><li>Polar </li></ul></ul>
  7. 7. Practice Problem #2 <ul><li>Are the following molecules polar or non-polar? </li></ul><ul><ul><li>MgCl 2 </li></ul></ul><ul><ul><li>CCl 4 </li></ul></ul><ul><ul><li>NH 3 </li></ul></ul>Polar Non-polar Polar
  8. 8. Solutions <ul><li>When one substance dissolves into another, that is called a SOLUTION </li></ul><ul><ul><li>Example: sugar water </li></ul></ul><ul><li>There are two main parts of a solution: </li></ul><ul><ul><li>SOLUTE= the dissolved material </li></ul></ul><ul><ul><ul><li>Example: sugar </li></ul></ul></ul><ul><ul><li>SOLVENT= the substance that is doing the dissolving (usually a liquid) </li></ul></ul><ul><ul><ul><li>Example: Water </li></ul></ul></ul>
  9. 9. Solutions <ul><li>Saturated solution </li></ul><ul><ul><li>Add a crystal and it will fall to the bottom </li></ul></ul><ul><li>Unsaturated solution </li></ul><ul><ul><li>Add a crystal and it will dissolve </li></ul></ul><ul><li>Supersaturated solution </li></ul><ul><ul><li>Add a crystal and it fills the container with crystals </li></ul></ul>
  10. 10. Solubility Curves <ul><li>The solubility of substances changes with temperature </li></ul><ul><ul><li>For example, is it easier to dissolve sugar in hot or cold coffee? </li></ul></ul><ul><li>Solids become more soluble at higher temperatures </li></ul><ul><li>Gases become less soluble at higher temperatures </li></ul>
  11. 11. Solubility Curves (cont.) <ul><li>Scientist have studied many substances solubility at different temperatures </li></ul><ul><ul><li>They created graphs which show this data </li></ul></ul>
  12. 12. Solubility Curves (cont.) <ul><li>Let’s simplify the graph with all the substances down to just one substance </li></ul>
  13. 13. Solubility Curves (cont.) <ul><li>What does this graph tell you about KCl at 80 ° C? </li></ul><ul><ul><li>52g of KCl dissolve in 100g of water </li></ul></ul>Is KCl a solid or gas in this graph?
  14. 14. Solubility Curves (cont.) <ul><li>How many grams of KCl will dissolve in 500g of water at 80 ° C? </li></ul><ul><ul><li>260g of KCl </li></ul></ul>
  15. 15. Solubility Curves (cont.) <ul><li>How many grams of water will it take to dissolve 29 g of KCl at 80 ° C? </li></ul><ul><ul><li>56g of H 2 O </li></ul></ul>
  16. 16. Solubility Curves (cont.) <ul><li>If one dissolves 95 grams of KCl in 250 grams of water at 80 ° C, what kind of solution will they have? </li></ul><ul><ul><li>Unsaturated </li></ul></ul>
  17. 17. Practice Problem #1 <ul><li>How many grams of NH 4 Cl will dissolve in 300 grams of water at 70 ° C? </li></ul><ul><li>If one dissolves 127.5 grams of NaNO 3 in 125 grams of water at 45 ° C, what kind of solution will they have? </li></ul>186g NH 4 Cl Unsaturated
  18. 18. Unit 6 Acid and Base Chemistry
  19. 19. Section 1 What are acids and bases?
  20. 20. Acid <ul><li>Substance that can give an H + ion </li></ul><ul><ul><li>HCl hydrochloric acid </li></ul></ul><ul><ul><li>H 2 SO 4 sulfuric acid </li></ul></ul><ul><ul><li>HNO 3 nitric acid </li></ul></ul>
  21. 21. Base <ul><li>Substance that can give an OH - ion </li></ul><ul><ul><li>NaOH sodium hydroxide </li></ul></ul><ul><ul><li>Mg(OH) 2 magnesium hydroxide </li></ul></ul><ul><ul><li>Al(OH) 3 aluminum hydroxide </li></ul></ul>
  22. 22. Acid/Base <ul><li>Properties of acids: </li></ul><ul><ul><li>Taste sour </li></ul></ul><ul><ul><li>Burn human skin </li></ul></ul><ul><ul><li>Neutralize bases </li></ul></ul><ul><ul><li>Corrode metals </li></ul></ul><ul><li>Properties of bases: </li></ul><ul><ul><li>Taste bitter </li></ul></ul><ul><ul><li>Break down human skin (denature proteins) </li></ul></ul><ul><ul><li>Neutralize acids </li></ul></ul>
  23. 23. Acid/Base (cont.) <ul><li>How can one recognize an acid by the chemical formula? </li></ul><ul><ul><li>Starts with an H </li></ul></ul><ul><li>How can one recognize a base by the chemical formula? </li></ul><ul><ul><li>Ends with an OH </li></ul></ul>
  24. 24. pH scale <ul><li>pH means the potential for hydrogen </li></ul><ul><ul><li>The ability of the solution to give of H + ions </li></ul></ul><ul><li>Indicates intensity of acid or base </li></ul><ul><li>0-14, 7 is considered neutral (in the middle) </li></ul><ul><li>The closer you get to 0, the more acidic </li></ul><ul><li>The closer you get to 14, the more basic </li></ul>
  25. 25. pH Scale <ul><li>Acidic </li></ul><ul><li>H+ Ions </li></ul><ul><li>Sour taste </li></ul><ul><li>Alkaline </li></ul><ul><li>OH- Ions </li></ul><ul><li>Bitter taste </li></ul>
  26. 26. Acid/Base (cont.) <ul><li>pH scale </li></ul>Which end of the spectrum is for acids and which end is for bases? <ul><ul><li>There are two indicators that you should know </li></ul></ul><ul><ul><ul><li>Phenolphthalein (clear or pink) </li></ul></ul></ul><ul><ul><ul><li>Litmus (red or blue) </li></ul></ul></ul>CLEAR PINK 0 7 14 acidic basic RED BLUE
  27. 27. Section 2 Indicators
  28. 28. Indicators <ul><li>Turn color to “indicate” the pH of the solution </li></ul>
  29. 29. Litmus Paper <ul><li>Great acid / base indicator </li></ul><ul><li>Acids = blue litmus turns RED </li></ul><ul><li>Bases = red litmus turns BLUE </li></ul>
  30. 30. Phenolphthalein <ul><li>Another great acid / base indicator </li></ul><ul><li>Clear colored as an acid </li></ul><ul><li>Pink colored as a base </li></ul>
  31. 31. Section 3 Acid / Base Reactions
  32. 32. Acid / Base Reactions <ul><li>Called “Neutralization” Reactions </li></ul><ul><li>Double Replacement Reactions </li></ul><ul><li>Acid + Base  Salt + Water </li></ul>
  33. 33. Example Acid + Base  Salt + Water +1 -1 +2 -1 +2 -1 +1 -1 H(NO 3 ) + Mg(OH) 2  Mg(NO 3 ) 2 + H(OH)