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Chapter 14 Acids, Bases, and pH. Comparing of Acids and Bases Observable properties – – Acids are sour – Bases are bitter and slippery to touch *** note.

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Presentation on theme: "Chapter 14 Acids, Bases, and pH. Comparing of Acids and Bases Observable properties – – Acids are sour – Bases are bitter and slippery to touch *** note."— Presentation transcript:

1 Chapter 14 Acids, Bases, and pH

2 Comparing of Acids and Bases Observable properties – – Acids are sour – Bases are bitter and slippery to touch *** note – taste and touch are not safe ways to test chemicals

3 Comparing of Acids and Bases Acids and bases turn certain dyes different colors – acids turn litmus dye red – bases turn litmus dye blue

4 Many common substances are acids or bases common acids – – citric acid, vinegar, – hydrochloric acid, – sulfuric acid common bases – – lye/soap, ammonia, – sodium hydroxide, – other metal hydroxides

5 Reactions Acids react with metals that are MORE active than hydrogen bases do NOT usually react with metals

6 Reactions acids also react with ionic compounds that contain the carbonate ion, CO 3 -2 reaction produces carbon dioxide gas, water, and another compound

7 Submicroscopic Behavior of Acids definition of acid – a substance that produces hydronium ions, H 3 O +, when it dissolves in H 2 O Ex. hydronium ions are formed from the transfer of a H + ion from the acid to H 2 O

8 Submicroscopic Behavior of Acids acidic hydrogen – any hydrogen atom that can be transferred to H 2 O. to distinguish acidic Hs from other Hs in the compound, acidic Hs are written 1 st. HClHC 2 H 3 O 2 HNO 3 H 2 SO 4

9 monoprotic acids contain only one acidic hydrogen

10 polyprotic acids with two acidic hydrogens are diprotic acids. polyprotic acids with three acidic hydrogens are triprotic acids

11 Chemical Reaction Shorthand general format for acid dissociation HA + H 2 O (l) H 3 O + (aq) + A - (aq) HA (aq) H+ (aq) + A- (aq) Reaction of acid and H 2 O to form ions is called acid ionization

12 Submicroscopic Behavior of Bases definition of base – a substance that produces hydroxide ions, OH - when dissolved in water 2 kinds – ionic bases – covalent bases

13 Simple Bases (ionic) metal hydroxide = metal ion + OH ion the metal hydroxide dissociates in H 2 O to form a metal ion and a hydroxide ion ***note - H 2 O does not react here, there is no actual transfer of ions as in the next example and with acids

14 Bases that Accept H + covalent bases react with H 2 O to form OH - ions there is a transfer of H + from the water to the base General equation for bases that accept H + : B + H 2 O (l) BH + (aq) + OH - (aq) NH 3 (g) + H 2 O (l) NH 4 + (aq) + OH - (aq) ammonia + water ammonium hydroxide solution

15 Other Acids and Bases certain compounds act like acids and bases- these compounds are: oxides -compounds with oxygen bonded to 1 other element they are called anhydrides - contain no water

16 Other Acids and Bases acidic anhydridesnonmetal oxides which react with water to form acids CO 2 + H 2 O H 2 CO 3 SO 3 + H 2 O H 2 SO

17 Other Acids and Bases basic anhydridesmetal oxides which react with water to form acids Na 2 O + H 2 O 2NaOH ZnO + H 2 O Zn(OH) 2

18 AcidBase ion produced when dissolved in H2O hydronium ions = H 3 O + produce hydroxide ions (OH - ) when dissolved in water propertiestart, sour,bitter, slippery, examplescitric acid, vinegar, hydrochloric acid, lye/soap, ammonia, metal hydroxides formulausually have H in front of the formula or at the end: HCl, CH 3 COOH usually have OH at the end of the formula: KOH, ammonia (NH 3 ) is also a base, litmusredblue pHless than 7greater than 7

19 Strengths of Acids and Bases strong acids completely dissociate into ions – no molecules left intact weak acids partially dissociate (not all come apart) into ions

20 Strengths of Acids and Bases strong bases completely dissociate (come apart) into ions weak bases partially dissociate (not all come apart) into ions

21 strength vs. concentration weak and strong refer to dissociation only concentrated & dilute = molarity(M); amount of particles in the solution

22 The pH Scale pH = mathmatical scale; range is 10 0 to = concentration of H 3 O + ions = number from 0 to 14. acid pH 7

23

24 pOH = concentration of OH - ions pH + pOH = 14 Water is mostly neutral [H + ] = [OH - ] Acidic solutions: [H+] > [OH-] Basic (alkaline) solutions: [OH-] > [H+]

25 pH of common substances

26 Example: If [H + ] of a solution = 1.0 x M a)Find pH. b)Find pOH. c)Find [OH - ]. d)Acid, base, or neutral? a) [H + ] = 1.0 x M b) pH + pOH = 14; 11 + pOH = 14 c) [H + ] [OH - ] = M [ ] [OH - ] = M d) pH > 7 pH = 11 pOH = 3 [OH - ] = M base

27 Example: If [OH-] of a solution = 1.0 x M a)Find pOH. b)Find pH. c)Find [H+]. d)Acid, base, or neutral? a) [OH-] = 1.0 x M b) pH + pOH = 14; pH + 9 = 14 c) [H + ] [OH - ] = M [H+] [10 -9 ] = M d) pH < 7 pOH = 9 pH = 5 [H+] = M acid


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