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Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
Concept Attainment   P H
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Concept Attainment P H

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  • 1.
    • pH
  • 2. REVIEWING SOME THINGS:
  • 3. Arrhenius Theory of Acids and Bases
      • An acid is a substance that produces H+ ions in solution
      • A base is a substance that produces OHˉ ions in solution
      • Neutralization can be represented by:
      • Arrhenius theory does not recognize the contribution of the solvent in the ionization of the solute
      • It fails to explain weak bases such as carbonate (CO 3 2- ), and ammonia (NH 3 )
    HCl (g) H + (aq) + Clˉ (aq) H 2 O NaOH (s) Na + (aq) + OHˉ (aq) H 2 O H + (aq) + OHˉ (aq) H 2 O (l)
  • 4. Br ø nsted Lowry Acid/Base Theory NaOH(s) + H 2 O(l) Na + (aq) + OHˉ(aq) HBr(g) + H 2 O(l) H 3 O + (aq) + Brˉ(aq)
    • For our purposes H 3 O + and H + can be considered equivalent terms
    • Neutralization can be represented by:
    H 3 O + (aq) + OHˉ (aq) 2 H 2 O (l)
  • 5. Br ø nsted Lowry Acid/Base Theory
    • The main advantage of the Br ø nsted Lowry Theory is in its treatment of weak bases
        • An acid is a proton (H + ) donor
        • A base is a proton (H + ) acceptor
      • Since NH 3 is a weak base, the reverse reaction should also be considered
      • This reversible reaction may be written as follows:
    NH 3 + H 2 O NH 4 + + OHˉ conjugate acid conjugate base acid base NH 3 + H 2 O NH 4 + + OHˉ base acid NH 4 + + OHˉ NH 3 + H 2 O base acid
  • 6. Review Question
    • Identifying Br ø nsted-Lowry Acids and Bases and their Conjugates
    Question: For each of the following chemical equations, identify the acids and bases in both the forward and reverse reactions. i) HClO 2 + H 2 O ClO 2 ˉ + H 3 O + ii) OClˉ + H 2 O HOCl + OHˉ iii) NH 3 + H 2 PO 4 ˉ NH 4 + + HPO 4 2 ˉ conjugate acid conjugate base acid base conjugate acid conjugate base acid base conjugate acid conjugate base acid base
  • 7. Last two things
    • Concentration – how much of something is contained in a certain amount of solution
    • Molarity – a chemical means of measuring concentration
  • 8. Concentration is measured in M
    • [C 6 H 12 O 6 ] = 5 M  “Five Molar glucose”
    • [C 6 H 12 O 6 ] = 2 M  “Two Molar glucose”
    • [C 6 H 12 O 6 ] = 0.5 M  “0.5 Molar glucose”
    • [C 6 H 12 O 6 ] = 0.2 M  “0.2 Molar glucose”
    • Which of these is the most concentrated?
    • Which of these is the least concentrated?
  • 9. What happens when the concentration gets really small?
    • [C 6 H 12 O 6 ] = 0.00001 M
    • [C 6 H 12 O 6 ] = 0.00000001 M
    • [C 6 H 12 O 6 ] = 0.00000000000001 M
    • We bring back SCIENTIFIC NOTATION!!!
    • 0.00001 M = 1 x 10 -5 M
    • 0.00000001 M = 1 x 10 -8 M
    • 0.00000000000001 M = 1 x 10 -14 M
  • 10. Let’s apply this concentration & scientific notation stuff to Acids/Bases
    • [HCl] = 0.00001 M
    • [CH 3 COOH] = 0.00000000000001 M
    • [HCl] = 1 x 10 -5 M
    • [CH 3 COOH] = 1 x 10 -14 M
  • 11. Let’s apply this concentration & scientific notation stuff to Acids/Bases
    • [HCl] & [CH 3 COOH] are acids
      • Acids  generate H +
    • So,
    • [HCl] = 1 x 10 -5 M  [H + ] = 1 x 10 -5 M
    • [CH 3 COOH] = 1 x 10 -14 M  [H + ] = 1 x 10 -14 M
  • 12. Now, let’s use the scientific notation…
    • Rank the following from least to greatest concentration of Hydrogen ions
    • [HCl] = 1 x 10 -6 M
    • [CH 3 COOH] = 1 x 10 -14 M
    • [HNO 3 ] = 1 x 10 -2 M
    • [HBr] = 1 x 10 -12 M
    • [HClO 3 ] = 1 x 10 -3 M
    • [HF] = 1 x 10 -13 M
  • 13.
    • [CH 3 COOH] = 1 x 10 -14 M
    • [HF] = 1 x 10 -13 M
    • [HBr] = 1 x 10 -12 M
    • [HCl] = 1 x 10 -6 M
    • [HClO 3 ] = 1 x 10 -3 M
    • [HNO 3 ] = 1 x 10 -2 M
    Regardless of the acid’s identity, the concentrations of H + ions rank as follows:
  • 14.
    • [H + ] = 1 x 10 -14 M
    • [H + ] = 1 x 10 -13 M
    • [H + ] = 1 x 10 -12 M
    • [H + ] = 1 x 10 -6 M
    • [H + ] = 1 x 10 -3 M
    • [H + ] = 1 x 10 -2 M
    • It means the same thing!!
    So, we might as well just write…
  • 15. Now, for the NEW idea: pH
    • See if you can figure out what is going on in the next slides…
  • 16. Part 1: Define a logarithm
    • When the [H + ] =
    • 1 x 10 -14 M -14
    • 1 x 10 -13 M -13
    • 1 x 10 -12 M -12
    • 1 x 10 -11 M -11
    • 1 x 10 -10 M -10
    • 1 x 10 -9 M -9
    • 1 x 10 -8 M -8
    • 1 x 10 -7 M -7
    • 1 x 10 -6 M -6
    • 1 x 10 -5 M -5
    • 1 x 10 -4 M -4
    • 1 x 10 -3 M -3
    • 1 x 10 -2 M -2
    • 1 x 10 -1 M -1
    • The logarithm of [H + ] =
  • 17. Part 2: How do we change the log result into a positive number? Multiply the log by -1 to change it to positive
    • When [H + ] = Log [H + ] = - Log [H + ] =
    • 1 x 10 -14 M -14 14
    • 1 x 10 -13 M -13 13
    • 1 x 10 -12 M -12 12
    • 1 x 10 -11 M -11 11
    • 1 x 10 -10 M -10 10
    • 1 x 10 -9 M -9 9
    • 1 x 10 -8 M -8 8
    • 1 x 10 -7 M -7 “times -1” 7
    • 1 x 10 -6 M -6 6
    • 1 x 10 -5 M -5 5
    • 1 x 10 -4 M -4 4
    • 1 x 10 -3 M -3 3
    • 1 x 10 -2 M -2 2
    • 1 x 10 -1 M -1 1
  • 18. It’s LOG!!!!
    • So, what does a log do?
      • It changes a number that is written in scientific notation into the EXPONENT of the scientific notation
    • What does -log do?
      • It changes a number that is written in scientific notation with a NEGATIVE EXPONENT into a POSITIVE NUMBER ALONE
  • 19. Part 3: pH
    • When the [H + ] =
    • 1 x 10 -14 M 14
    • 1 x 10 -13 M 13
    • 1 x 10 -12 M 12
    • 1 x 10 -11 M 11
    • 1 x 10 -10 M 10
    • 1 x 10 -9 M 9
    • 1 x 10 -8 M 8
    • 1 x 10 -7 M 7
    • 1 x 10 -6 M 6
    • 1 x 10 -5 M 5
    • 1 x 10 -4 M 4
    • 1 x 10 -3 M 3
    • 1 x 10 -2 M 2
    • 1 x 10 -1 M 1
    • The pH =
  • 20. So, what is pH ?
    • A mathematical operation
      • Just like Sum, Difference, Product, etc.
    • It does the same thing that taking the –log of a number does!!!
      • The “p” means ‘take the negative log of’
      • The H stands for [H + ]
      • Thus,
      • pH = -log [H + ]
  • 21. Find the pH of each of the following
    • Concentration
    • [HCl] = 1 x 10 -6 M
    • [CH 3 COOH] = 1 x 10 -14 M
    • [HNO 3 ] = 1 x 10 -2 M
    • [HBr] = 1 x 10 -12 M
    • [HClO 3 ] = 1 x 10 -3 M
    • [HF] = 1 x 10 -13 M
    pH 6 14 2 12 3 13
  • 22. What did you notice about the pH scale compared to concentration? The smaller the pH the higher the concentration of the [H + ]
  • 23. Let’s try our using pH to rank acid strength
  • 24. Now, let’s use the scientific notation…
    • Rank the following from least to greatest concentration of Hydrogen ions
    • pH of HCl = 6
    • pH of CH 3 COOH = 2
    • pH of HNO 3 = 3
    • pH of HBr = 11
    • pH of HClO 3 = 8
    • pH of HF = 10
  • 25. The following are ranked from LEAST to GREATEST [H + ]
    • pH of HBr = 11
    • pH of HF = 10
    • pH of HClO 3 = 8
    • pH of HCl = 6
    • pH of HNO 3 = 3
    • pH of CH 3 COOH = 2
    The smaller the pH the higher the concentration of the [H + ]
  • 26. Why use pH?
    • It’s much more convenient way of measuring [H + ] than using scientific notation
      • It transforms the negative exponents into positive numbers
    • We can use pH to talk about acid strength
  • 27. The pH scale 1 2 3 4 5 6 7 8 9 10 11 12 13 14
  • 28. The Acid Concentration Scale When [H + ] = 1 x 10 to the… -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14
  • 29. Let’s see if the pH concept makes sense to you
    • What does the “H” part of pH mean?
    • What does the “p” part of pH mean?
    • What does taking the log of a number do?
    • What does taking the –log of a number do?
    • Could pH work for ions other than [H + ]?
      • Could we take a pOH perhaps???
  • 30. pOH: the flip-side of pH
    • Works JUST LIKE pH, except we are talking now about the [OH - ] instead of [H + ]
    • What is the pOH of a NaOH solution that is 1 x 10 -3 M?
    • pOH = 3
  • 31. The pOH scale 1 2 3 4 5 6 7 8 9 10 11 12 13 14
  • 32. The Base Concentration Scale When [OH - ] = 1 x 10 to the… -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14
  • 33. Find the pOH of each of the following
    • Concentration
    • [NaOH] = 1 x 10 -6 M
    • [KOH] = 1 x 10 -14 M
    • [LiOH] = 1 x 10 -2 M
    pOH 6 14 2
  • 34. What’s the relationship between pH and pOH?
    • pH + pOH = 14 ALWAYS!!!
  • 35. pH and pOH
    • The potential of the hydrogen ion was defined in 1909 as the negative of the logarithm of [H + ].
    pH = -log[H 3 O + ] pOH = -log[OH - ] [H 3 O + ][OH - ]= 1.0x10 -14 pH + pOH = 14
  • 36. Sample Question
    • Calculate the pH and pOH of 0.10 M HBr
    HBr + H 2 O H 3 O + + Brˉ For our purposes H 3 O + and H + can be considered equivalent terms pH = -log [H + ] pH = -log (0.1) pH = 1.0 Since pH + pOH = 14 1.0 + pOH = 14 pOH = 13
  • 37. Another Sample Question
    • Calculate the pH of 0.10 M KOH
    KOH is a strong base and will fully dissociate; [OHˉ] = 0.10M Method # 2 Calculate pOH pOH = -log [OH ˉ ] pOH = -log (0.1) pOH = 1.0 pH + pOH = 14 pH + 1 = 14 pH = 13 Calculate pH
  • 38. Why pH/pOH?? Autoprotolysis of Water H 2 O + H 2 O H 3 O + + OH - base acid c. acid c. base K c = [H 2 O][H 2 O] [H 3 O + ][OH - ] K W = K c [H 2 O][H 2 O] = = 1.0x10 -14 [H 3 O + ][OH - ] K W = = 1.0x10 -14 [H 3 O + ][OH - ]

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