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Acids Lesson 9 Ionization of Water. The pH Scale Water ionizes to a small degree. H 2 O (l) ⇄ H + +OH - 2H 2 O (l) ⇄ H 3 O + +OH - Kw = [H + ][OH - ]=1.0x.

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Presentation on theme: "Acids Lesson 9 Ionization of Water. The pH Scale Water ionizes to a small degree. H 2 O (l) ⇄ H + +OH - 2H 2 O (l) ⇄ H 3 O + +OH - Kw = [H + ][OH - ]=1.0x."— Presentation transcript:

1 Acids Lesson 9 Ionization of Water

2 The pH Scale Water ionizes to a small degree. H 2 O (l) ⇄ H + +OH - 2H 2 O (l) ⇄ H 3 O + +OH - Kw = [H + ][OH - ]=1.0x 10 -14 @ 25 0 C [H + ] and [OH - ] are inversely related! 1.Calculate the [H + ] and [OH - ] in 1.0 M HCl. HCl  H + +Cl - 1.0 M1.0 M1.0 M [H + ][OH - ]=1.0x 10 -14 [1.0][OH - ]=1.0x 10 -14 [OH - ]=1.0x 10 -14 M Note that in acid solution the [H + ] is large and the [OH - ] is small.

3 2.Calculate the [H + ] and [OH - ] in 1.0 M Ba(OH) 2. Ba(OH) 2  Ba 2+ +2OH - 1.0 M1.0 M2.0 M [H + ][OH - ]=1.0x 10 -14 [H + ][2.0]=1.0x 10 -14 [H + ]=5.0x 10 -15 M In a basic solution the [OH - ] is very large and the [H + ] is very small!

4 3.Calculate the [H + ] and [OH - ] in H 2 O. The ionization of water. H 2 O ⇄ H + +OH -x [H + ][OH - ]=1.0x 10 -14 x 2 =1.0x 10 -14 [OH - ] =[H + ]=1.0x 10 -7 M Note that in pure water that the [H + ] and the [OH - ] are equal!

5 4.The pH scale has three important end points. pH 0Strong Acid1.0 M HCl 7NeutralH 2 Oor NaCl 14Strong Base1.0 M NaOH

6 The pH scale 1.0 M HCl H 2 O1.0 M NaOH pH 0 7 14

7 pH 0 7 14 A B C D E 5.Match each letter with a formula. All are 1 M. NH 3

8 pH 0 7 14 A B C D E 5.Match each letter with a formula. All are 1 M. NH 3 weak baseD HCl

9 pH 0 7 14 A B C D E 5.Match each letter with a formula. All are 1 M. NH 3 weak baseD HClstrong acidA KOH

10 pH 0 7 14 A B C D E 5.Match each letter with a formula. All are 1 M. NH 3 weak baseD HClstrong acidA KOHstrong baseE HF

11 pH 0 7 14 A B C D E 5.Match each letter with a formula. All are 1 M. NH 3 weak baseD HClstrong acidA KOHstrong baseE HFweak acidB H 2 O

12 pH 0 7 14 A B C D E 5.Match each letter with a formula. All are 1 M. NH 3 weak baseD HClstrong acidA KOHstrong baseE HFweak acidB H 2 OneutralC

13 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH

14 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH We start the pH scale at 1.0 M HCl strong acid. 1.0 is the same as 1.0 x 10 0

15 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M

16 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M Substitute in the [H + ] and solve for [OH - ]

17 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M Substitute in the [H + ] and solve for [OH - ] [H + ][OH - ] = 1.0 x 10 -14

18 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M Substitute in the [H + ] and solve for [OH - ] [H + ][OH - ] = 1.0 x 10 -14 [1][OH - ] = 1.0 x 10 -14

19 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M Substitute in the [H + ] and solve for [OH - ] [H + ][OH - ] = 1.0 x 10 -14 [1][OH - ] = 1.0 x 10 -14 [OH - ] = 1.0 x 10 -14 M

20 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 MLet's decrease the [H + ] by a factor of 10 and solve for [OH - ]

21 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M

22 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 MLet's decrease the [H + ] by a 1.0 x 10 -1 M1.0 x 10 -13 Manother factor of 10 and solve for [OH - ]

23 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M

24 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M

25 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M

26 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 MNote, this is neutral solution!

27 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M

28 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M

29 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M 1.0 x 10 -11 M1.0 x 10 -3 M 1.0 x 10 -12 M1.0 x 10 -2 M

30 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M 1.0 x 10 -11 M1.0 x 10 -3 M 1.0 x 10 -12 M1.0 x 10 -2 M 1.0 x 10 -13 M1.0 x 10 -1 M 1.0 x 10 -14 M1.0 x 10 0 MNote this is the other end of the pH scale where [OH - ] = 1.0 M

31 Notice that the [H + ] scale goes from 1.0 M to 1.0 x 10 -14 M going from 1.0 M strong acid to 1.0 M strong base. This means that the [H + ] is changing by a factor of: 1.0=1.0 x 10 14 1.0 x 10 -14 There appears to be a need to simplify the scale. Why not take the power of the hydrogen ion concentration and get a scale from 0 to -14. We could take the negative of this and get a simple scale from 0 to 14. This is called the pH scale.

32 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M 1.0 x 10 -11 M1.0 x 10 -3 M 1.0 x 10 -12 M1.0 x 10 -2 M 1.0 x 10 -13 M1.0 x 10 -1 M 1.0 x 10 -14 M1.0 x 10 0 M

33 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M 1.0 x 10 -11 M1.0 x 10 -3 M 1.0 x 10 -12 M1.0 x 10 -2 M 1.0 x 10 -13 M1.0 x 10 -1 M 1.0 x 10 -14 M1.0 x 10 0 M

34 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M0 1.0 x 10 -1 M1.0 x 10 -13 M 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M 1.0 x 10 -11 M1.0 x 10 -3 M 1.0 x 10 -12 M1.0 x 10 -2 M 1.0 x 10 -13 M1.0 x 10 -1 M 1.0 x 10 -14 M1.0 x 10 0 M

35 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M0 1.0 x 10 -1 M1.0 x 10 -13 M1 1.0 x 10 -2 M1.0 x 10 -12 M 1.0 x 10 -3 M1.0 x 10 -11 M 1.0 x 10 -4 M1.0 x 10 -10 M 1.0 x 10 -5 M1.0 x 10 -9 M 1.0 x 10 -6 M1.0 x 10 -8 M 1.0 x 10 -7 M1.0 x 10 -7 M 1.0 x 10 -8 M1.0 x 10 -6 M 1.0 x 10 -9 M1.0 x 10 -5 M 1.0 x 10 -10 M1.0 x 10 -4 M 1.0 x 10 -11 M1.0 x 10 -3 M 1.0 x 10 -12 M1.0 x 10 -2 M 1.0 x 10 -13 M1.0 x 10 -1 M 1.0 x 10 -14 M1.0 x 10 0 M

36 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M0 1.0 x 10 -1 M1.0 x 10 -13 M1 1.0 x 10 -2 M1.0 x 10 -12 M2 1.0 x 10 -3 M1.0 x 10 -11 M3 1.0 x 10 -4 M1.0 x 10 -10 M4 1.0 x 10 -5 M1.0 x 10 -9 M5 1.0 x 10 -6 M1.0 x 10 -8 M6 1.0 x 10 -7 M1.0 x 10 -7 M7 1.0 x 10 -8 M1.0 x 10 -6 M8 1.0 x 10 -9 M1.0 x 10 -5 M9 1.0 x 10 -10 M1.0 x 10 -4 M10 1.0 x 10 -11 M1.0 x 10 -3 M11 1.0 x 10 -12 M1.0 x 10 -2 M12 1.0 x 10 -13 M1.0 x 10 -1 M13 1.0 x 10 -14 M1.0 x 10 0 M14

37 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M0We can do the same 1.0 x 10 -1 M1.0 x 10 -13 M1with the pOH 1.0 x 10 -2 M1.0 x 10 -12 M2 1.0 x 10 -3 M1.0 x 10 -11 M3 1.0 x 10 -4 M1.0 x 10 -10 M4 1.0 x 10 -5 M1.0 x 10 -9 M5 1.0 x 10 -6 M1.0 x 10 -8 M6 1.0 x 10 -7 M1.0 x 10 -7 M7 1.0 x 10 -8 M1.0 x 10 -6 M8 1.0 x 10 -9 M1.0 x 10 -5 M9 1.0 x 10 -10 M1.0 x 10 -4 M10 1.0 x 10 -11 M1.0 x 10 -3 M11 1.0 x 10 -12 M1.0 x 10 -2 M12 1.0 x 10 -13 M1.0 x 10 -1 M13 1.0 x 10 -14 M1.0 x 10 0 M14

38 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M014 1.0 x 10 -1 M1.0 x 10 -13 M113 1.0 x 10 -2 M1.0 x 10 -12 M212 1.0 x 10 -3 M1.0 x 10 -11 M311 1.0 x 10 -4 M1.0 x 10 -10 M410 1.0 x 10 -5 M1.0 x 10 -9 M59 1.0 x 10 -6 M1.0 x 10 -8 M68 1.0 x 10 -7 M1.0 x 10 -7 M77 1.0 x 10 -8 M1.0 x 10 -6 M86 1.0 x 10 -9 M1.0 x 10 -5 M95 1.0 x 10 -10 M1.0 x 10 -4 M104 1.0 x 10 -11 M1.0 x 10 -3 M113 1.0 x 10 -12 M1.0 x 10 -2 M122 1.0 x 10 -13 M1.0 x 10 -1 M131 1.0 x 10 -14 M1.0 x 10 0 M140

39 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M014 1.0 x 10 -1 M1.0 x 10 -13 M113 1.0 x 10 -2 M1.0 x 10 -12 M212 1.0 x 10 -3 M1.0 x 10 -11 M311 1.0 x 10 -4 M1.0 x 10 -10 M410 1.0 x 10 -5 M1.0 x 10 -9 M59 1.0 x 10 -6 M1.0 x 10 -8 M68 Note that the pH + pOH = 14 1.0 x 10 -7 M1.0 x 10 -7 M77 @ 25 0 C 1.0 x 10 -8 M1.0 x 10 -6 M86 1.0 x 10 -9 M1.0 x 10 -5 M95 1.0 x 10 -10 M1.0 x 10 -4 M104 1.0 x 10 -11 M1.0 x 10 -3 M113 1.0 x 10 -12 M1.0 x 10 -2 M122 1.0 x 10 -13 M1.0 x 10 -1 M131 1.0 x 10 -14 M1.0 x 10 0 M140

40 pHScaleKw = [H + ][OH - ]= 1.0x 10 -14 [H + ][OH - ]pHpOH 1.0 x 10 0 M1.0 x 10 -14 M014 1.0 x 10 -1 M1.0 x 10 -13 M113 1.0 x 10 -2 M1.0 x 10 -12 M212 1.0 x 10 -3 M1.0 x 10 -11 M311 1.0 x 10 -4 M1.0 x 10 -10 M410 1.0 x 10 -5 M1.0 x 10 -9 M59 1.0 x 10 -6 M1.0 x 10 -8 M68 Note that the the scale can go 1.0 x 10 -7 M1.0 x 10 -7 M77 to -1 and 15 1.0 x 10 -8 M1.0 x 10 -6 M86 1.0 x 10 -9 M1.0 x 10 -5 M95 1.0 x 10 -10 M1.0 x 10 -4 M104 1.0 x 10 -11 M1.0 x 10 -3 M113 1.0 x 10 -12 M1.0 x 10 -2 M122 1.0 x 10 -13 M1.0 x 10 -1 M131 1.0 x 10 -14 M1.0 x 10 0 M140 15


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