1 The Chemistry of Acids and Bases

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3 Acid and Bases

4 Vinegar Acetic Acid Or Vinegar Acetic Acid Or Vinegar Vinegar is a weak acid that has many household uses Vinegar is a weak acid that has many household uses

5 Acid and Bases

6 Acids

7 Dissociation of Acids HNO 3 (l) + H 2 O (l)  H (aq) + NO 3 - (aq) H 3 O + is called a hydronium ion

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9 Some Properties of Acids þ Produce H 3 O + ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) þ Taste sour þ Reacts with a metal to produce hydrogen gas þ Electrolytes þ React with bases to form a salt and water þ pH is less than 7 þ Turns blue litmus paper to red “Blue to Red A-CID”

10 Naming Acids and Bases A Review

11 Acid Nomenclature Review Binary  Ternary An easy way to remember which goes with which… “In the cafeteria, you ATE something ICky”

12 Acid Nomenclature Flowchart

13 HBr (aq)HBr (aq) H 2 CO 3H 2 CO 3 H 2 SO 3H 2 SO 3  hydrobromic acid  carbonic acid  sulfurous acid Acid Nomenclature Review

14 Name ‘Em! HCl (aq) HI (aq) H 2 SO 4 (aq) HNO 2 (aq) HIO 3 (aq)  Hydrochloric acid  Hydroiodic acid  Sulfuric acid  Nitrous acid  Iodic acid

15 Bases

16 Some Properties of Bases  Produce OH - ions in water  Taste bitter, chalky  Are electrolytes  Feel soapy, slippery  React with acids to form salts and water  pH greater than 7  Turns red litmus paper to blue “Basic Blue”

17 Some Common Bases NaOHsodium hydroxidelye KOHpotassium hydroxideliquid soap Ba(OH) 2 barium hydroxidestabilizer for plastics Mg(OH) 2 magnesium hydroxide“MOM” Milk of magnesia Al(OH) 3 aluminum hydroxideMaalox (antacid) Al(OH) 3 aluminum hydroxideMaalox (antacid)

18 Acid Base Theories

19 Acid/Base definitions Definition #1: Arrhenius (traditional) Acids – produce H + ions which produce hydronium ion (H 3 O + ) when dissolved in water. Bases – produce OH - ions (problem: some bases don’t have hydroxide ions!)

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21 Arrhenius acid is a substance that produces H + (H 3 O + ) in water Arrhenius base is a substance that produces OH - in water

22 Acid/Base Definitions Definition #2: Brønsted – Lowry Acids – proton donor Bases – proton acceptor A “proton” is really just a hydrogen atom that has lost it’s electron!

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24 A Brønsted-Lowry acid is a proton donor A Brønsted-Lowry base is a proton acceptor acidbase Accepts a Proton or H + Accepts a Proton or H + Donates a Proton or H + Donates a Proton or H +

25 Acids & Base Definitions Lewis acid - a substance that accepts an electron pair Lewis base - a substance that donates an electron pair Definition #3 – Lewis

26 Lewis Acid/Base Reaction

27 pH Scale

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29 The pH scale is a way of expressing the strength of acids and bases. Instead of using very small numbers, we just use the NEGATIVE power of 10 on the Molarity of the H 3 O + (or OH - ) ion. pH under 7 = acid pH 7 = neutral pH over 7 = base pH under 7 = acid pH 7 = neutral pH over 7 = base

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31 pH of Common Substances

32 Calculating the pH pH = - log [H 3 O + ] (Remember that the [ ] mean Molarity) Example: If [H 3 O + ] = 1 X pH = - log 1 X pH = - (- 10) pH = 10 Example: If [H 3 O + ] = 1.8 X pH = - log 1.8 X pH = - (- 4.74) pH = 4.7

33 Try These! Find the pH of these: 1)A 0.15 M solution of Hydrochloric acid Answer: pH =.82 2) A 3.00 X M solution of Nitric acid Answer: pH = 6.52

34 pH calculations – Solving for H 3 O+ If the pH of Coke is 3.12, what is the [H 3 O + ]? Because pH = - log [H 3 O + ] then - pH = log [H 3 O + ] Take antilog (10 x ) of both sides *** to find antilog on your calculator, *** to find antilog on your calculator, look for “Shift” or “2 nd function” and then the log button [H 3 O + ] = 10 -pH [H 3 O + ] = = 7.59 x M (On your calculator: 2 nd, log, -3.12, enter)

35 You try this A solution has a pH of 8.5. What is the molarity of hydronium (H 3 O + ) ions in the solution?A solution has a pH of 8.5. What is the molarity of hydronium (H 3 O + ) ions in the solution? - log [H 3 O + ] = pH - log [H 3 O + ] = 8.5 log [H 3 O + ] = antilog (log [H3O+]) = Antilog -8.5 [H 3 O + ] = [H 3 O + ] = [H 3 O + ] = 3.2 X M - log [H 3 O + ] = pH - log [H 3 O + ] = 8.5 log [H 3 O + ] = antilog (log [H3O+]) = Antilog -8.5 [H 3 O + ] = [H 3 O + ] = [H 3 O + ] = 3.2 X M

36 pOH Since acids and bases are opposites, pH and pOH are opposites!Since acids and bases are opposites, pH and pOH are opposites! pOH does not really exist, but it is useful for changing bases to pH.pOH does not really exist, but it is useful for changing bases to pH. pOH looks at the perspective of a basepOH looks at the perspective of a base pOH = - log [OH - ] Since pH and pOH are on opposite ends, pH + pOH = 14

37 pH vs pOH Scale

38 [H 3 O + ], [OH - ] and pH What is the pH of a M NaOH solution? pOH = - log pOH = - log pOH = 3 pH = 14 – 3 = 11 pH = 14 – 3 = 11

39 Strong and Weak Acids and Bases

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41 H 2 SO 4, HNO 3, HCl, HBr, HI, and HClO 4 are among the only known strong acids. Strong and Weak Acids The strength of an acid is determined by the amount of IONIZATION or DISSOCIATION when put in water.

42 The strength of an base is determined by the amount of IONIZATION or DISSOCIATION when put in water. NaOH (aq) ---> Na + (aq) + OH - (aq) NaOH (aq) ---> Na + (aq) + OH - (aq) Strong and Weak Bases Strong bases include KOH, NaOH, RbOH, CsOH, Ca(OH) 2, Sr(OH) 2, and Ba(OH) 2

43 Ways to find pH

44 Finding the pH Paper tests Litmus paper Blue to red is “a-cid” Red to blue is base pH paper Turns various colors according to the pH

45 Finding the pH pH Meter Tests the voltage of the electrolyte Converts the voltage to pH Very cheap, accurate Must be calibrated with a buffer solution

46 pH indicators Indicators are dyes that can be added that will change color in the presence of an acid or base. Some indicators only work in a specific range of pH Once the drops are added, the sample is ruined Some dyes are natural, like radish skin or red cabbage

47 Titration

48 Setup for titrating an acid with a base

49 TitrationTitration 1. Add solution from the buret. 2. Reagent (base) reacts with compound (acid) in solution in the flask. 3.Indicator shows when exact neutralization reaction has occurred. (Acid = Base) This is called NEUTRALIZATION. This is called NEUTRALIZATION.

50 Does this look familiar? Does this look familiar? M 1 V 1 = M 2 V 2 Finding Molarity by Titration