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Chapter 7 Acids and Bases. Arrhenius Definitions - Acids produce hydrogen ion in aqueous, and bases produce hydroxide ions. Brønsted-Lowry Definitions.

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Presentation on theme: "Chapter 7 Acids and Bases. Arrhenius Definitions - Acids produce hydrogen ion in aqueous, and bases produce hydroxide ions. Brønsted-Lowry Definitions."— Presentation transcript:

1 Chapter 7 Acids and Bases

2 Arrhenius Definitions - Acids produce hydrogen ion in aqueous, and bases produce hydroxide ions. Brønsted-Lowry Definitions - An acid is a proton (H + ) donor, and a base is a proton acceptor. Lewis Acid-Base Definitions - An acid as an electron pair acceptor and a base as an electron donor.

3 An Acid is Dissolved in Water acidbase conjugate acid conjugate base

4 Conjugate Acid-Base Pair Conjugate acid-base pair consists of two substances related to each other by the donating and accepting of a single proton.

5 Water as an Acid and a Base Water is the common amphoteric substance. K w =[H 3 O + ][OH - ]=1×10 -14 ion-product constant pH=-log[H + ]

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7 Calculating the pH of Weak Acid Solutions 1.0M Before 0 0 Equilibrium (1-x)MxMxMxMxM

8 The 5% Rule The validity of an approximation should always be check. The 5% rule should be used to evaluate which approximation are reasonable. The approximation is acceptable.

9 The pH of a Mixture of Weak Acids HNO 2 is assumed to be the dominant producer of H +.

10 5 00 5-x xx

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12 Percent Dissociation 0.1 00 0.1-xxx

13 Polyprotic Acids Diprotic Acids

14 The Concentration of Species of Polyprotic Acid As a Function of pH

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16 Polyprotic Acid - H 3 PO 4

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18 Calculate the equilibrium concentration of the different species in a 0.1 M phosphoric acid solution at pH=3.

19 Acid-Base Properties of Salts Salt that produce neutral solutions Salts that consist of the cations of strong bases and the anions of strong acids have no effect on [H + ] when dissolved in water. The aqueous solutions of salts such as KCl, NaCl, NaNO 3 and KNO 3 are neutral.

20 Acid-Base Properties of Salts Salt that produce basic solutions

21 Acid-Base Properties of Salts Salt that produce acidic solutions

22 Water Contributes to the Very Dilute H + Concentration

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24 If [H + ] 2 >>K w, the full equation reduces to the typical expression for a weak acid.


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