1 Chapter 9 Acids and Bases Acids and Bases

2 Acids and Bases – What they do in water Acids produce H + in aqueous solutions water HCl H + (aq) + Cl - (aq) Bases produce OH - in aqueous solutions water NaOH Na + (aq) + OH - (aq)

3 Acids þ Produce H + (as H 3 O + ) ions in water þ Produce a negative ion (-) too þ Taste sour þ Corrode metals þ React with bases to form salts and water

4 Bases Produce OH - ions in water Taste bitter, chalky Are electrolytes Feel soapy, slippery React with acids to form salts and water

5 Learning Check AB1 Describe the solution in each of the following as: 1) acid 2) base or 3)neutral. A. ___soda B. ___soap C. ___coffee D. ___ wine E. ___ water F. ___ grapefruit

6 Solution AB1 Describe each solution as: 1) acid 2) base or 3) neutral. A. _1_ soda B. _2_ soap C. _1_ coffee D. _1_ wine E. _3_ water F. _1_ grapefruit

7 Learning Check AB2 Identify each as characteristic of an A) acid or B) base ____ 1. Sour taste ____ 2. Produces OH - in aqueous solutions ____ 3. Chalky taste ____ 4. Is an electrolyte ____ 5. Produces H + in aqueous solutions

8 Solution AB2 Identify each as a characteristic of an A) acid or B) base _A_ 1. Sour taste _B_ 2. Produces OH - in aqueous solutions _B_ 3. Chalky taste A, B 4. Is an electrolyte _A_ 5. Produces H + in aqueous solutions

9 Some Common Acids HCl hydrochloric acid HNO 3 nitric acid H 3 PO 4 phosphor ic acid H 2 SO 4 sulfur ic acid CH 3 COOH acet ic acid

10 Learning Check AB3 Give the names of the following A. HBr (aq)1. bromic acid 2. bromous acid 3. hydrobromic acid B. H 2 CO 3 1. carbonic acid 2. hydrocarbonic acid 3. carbonous acid

11 Solution AB3 A. HBr3. hydrobromic acid The name of a nonoxy acid begins with the prefix hydro- and ends with -ic acid. In a nonoxy acid, the negative anion end in -ide. B. H 2 CO 3 1. carbonic acid The name of an oxyacid is named with the stem of the anion (carbonate) changed to -ic acid

12 Some Common Bases NaOHsodium hydroxide KOH potassium hydroxide Ba(OH) 2 ________________________ Mg(OH) 2 ________________________ Al(OH) 3 aluminum hydroxide

13 Learning Check AB4 Match the formulas with the names: A. ___ HNO 2 1) hydrochloric acid B. ___Ca(OH) 2 2) sulfuric acid C. ___H 2 SO 4 3) sodium hydroxide D. ___HCl4) nitrous acid E. ___NaOH5) calcium hydroxide

14 Solution AB4 Match the formulas with the names: A. _4__ HNO 2 1) hydrochloric acid B. _5__Ca(OH) 2 2) sulfuric acid C. _2__H 2 SO 4 3) sodium hydroxide D. _1__HCl4) nitrous acid E. _3__NaOH5) calcium hydroxide

15 Learning Check AB5 Acid, Base Name or Salt CaCl 2 _______________________ KOH_______________________ Ba(OH) 2 ______ _________________ HBr_______________________ H 2 SO 4 ________________________

16 Solution AB5 Acid, Base Name or Salt CaCl 2 saltcalcium chloride KOHbasepotassiuim hydroxide Ba(OH) 2 basebarium hydroxide HBracidhydrobromic acid H 2 SO 4 acidsulfuric acid

17 Acids & Bases – What they do with H + Acids are hydrogen ion (H +) donors Bases are hydrogen ion (H + ) acceptors HCl + H 2 O H 3 O + + Cl - donor acceptor + - +

18 Neutralization Reactions When acid and bases with equal amounts of hydrogen ion H + and hydroxide ions OH - are mixed, the resulting solution is neutral. NaOH (aq) + HCl(aq) NaCl + H 2 O base acid salt water Ca(OH) HCl CaCl 2 + 2H 2 O base acid salt water

19 Neutralization H 3 O + and OH - combine to produce water H 3 O + + OH -  2 H 2 O from acid from base neutral Net ionic equation: H + + OH -  H 2 O

20 Ionization of Water Occasionally, in water, a H + is transferred between H 2 O molecules H : O : + : O : H H : O : H + + : O : H H H H water molecules hydronium hydroxide ion (+) ion (-)

21 Pure Water is Neutral Pure water contains small, but equal amounts of ions: H 3 O + and OH - H 2 O + H 2 O H 3 O + + OH - hydronium hydroxide ion ion 1 x M H3O+H3O+ OH -

22 Ion Product of Water K w [ ] = Molar concentration K w = [ H 3 O + ] [ OH - ] = [ 1 x ][ 1 x ] = 1 x

23 Acids Increase H + HCl (g) + H 2 O (l) H 3 O + (aq) + Cl - (aq) More [H 3 O + ] than water > 1 x M As H 3 O + increases, OH - decreases [H 3 O + ] > [OH - ] H3O+H3O+ OH -

24 Bases Increase the hydroxide ions (OH - ) H 2 O NaOH (s) Na + (aq) + OH - (aq) More [OH - ] than water, [OH - ] > 1 x M When OH - increases, H 3 O + decreases [OH  ] > [H 3 O + ] H3O+H3O+ OH -

25 pH Indicates the acidity [H 3 O + ] of the solution pH = - log [H 3 O + ] From the French pouvoir hydrogene (“hydrogen power” or power of hydrogen)

26 Concentration changes by powers of 10 pH =1 has 10x more than pH = 2 pH = 1 has 100x more than pH = 3 More  Less

27 In the expression for [H 3 O + ] 1 x 10 -exponent the exponent = pH [H 3 O + ] = 1 x 10 -pH M pH

28 pH Range Neutral [H + ] > [OH - ] [H + ] = [OH - ] [OH - ] > [H + ] Acidic Basic

29 Some [H 3 O + ] and pH [H 3 O + ] pH 1 x M 5 1 x M 9 1 x M 11

NeutralWeak Alkali Strong Alkali Weak Acid Strong Acid The pH Scale

31 Detecting Acids and Bases You can detect an acid using an indicator. INDICATOR - A substance that changes color in the presence of an acid or a base.

32 INDICATORS Litmus paper is an indicator  An acid turns blue litmus paper red  A base turns red litmus paper blue Cabbage juice can be used as an indicator

33 There are several ways to test pHThere are several ways to test pH –Blue litmus paper (red = acid) –Red litmus paper (blue = basic) –pH paper (multi-colored) –pH meter (7 is neutral, 7 base) –Universal indicator (multi-colored) –Indicators like phenolphthalein –Natural indicators like red cabbage, radishes

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