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Introduction to Acids, Bases. Arrhenius Definition of Acids and Bases Acids dissociate to produce H + ions in aqueous (water) solutions Acids dissociate.

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Presentation on theme: "Introduction to Acids, Bases. Arrhenius Definition of Acids and Bases Acids dissociate to produce H + ions in aqueous (water) solutions Acids dissociate."— Presentation transcript:

1 Introduction to Acids, Bases

2 Arrhenius Definition of Acids and Bases Acids dissociate to produce H + ions in aqueous (water) solutions Acids dissociate to produce H + ions in aqueous (water) solutions HCl H + (aq) + Cl - (aq) Bases dissociate to produce OH - ions in aqueous (water) solutions Bases dissociate to produce OH - ions in aqueous (water) solutions NaOH Na + (aq) + OH - (aq)

3 Dissociation Dissociation: when a compound splits apart into ions in solution. Dissociation: when a compound splits apart into ions in solution. How might these dissociate? H 2 SO 4 KOH DO NOW: Packet page 3, #7 Practice Writing Dissociation Equations

4 Note: Note: Acids and Bases are only reactive if their ions are dissociated (when aqueous) Acids and Bases are only reactive if their ions are dissociated (when aqueous) HCl (l) = hydrogen chloride HCl (l) = hydrogen chloride HCl (aq) = hydrochloric acid HCl (aq) = hydrochloric acid

5 Getting to Know Some Acids

6 6 Some Common Acids See Table K HCl hydrochloric acid HNO 3 nitric acid H 3 PO 4 phosphor ic acid H 3 PO 4 phosphor ic acid H 2 SO 4 sulfur ic acid HC 2 H 3 O 2 acet ic acid

7 The Hydronium Ion (H ) Acids produce the H + ion Acids produce the H + ion This is just a “bare proton” and is very reactive. This is just a “bare proton” and is very reactive. It immediately forms a coordinate covalent bond with nearby water molecules to form (H ). It immediately forms a coordinate covalent bond with nearby water molecules to form (H ). Do Now: Draw the formation of the Hydronium Ion

8 Organic Acids Contain carbon Contain carbon Only one of the hydrogens is “acidic” and dissociates in solution Only one of the hydrogens is “acidic” and dissociates in solution Ex:Acetic Acid Ex:Acetic Acid HC 2 H 3 O 2 or CH 3 COOH HC 2 H 3 O 2 or CH 3 COOH

9 Naming Acids (Honors) Binary Acids Binary Acids (Contain 2 elements only) (Contain 2 elements only) Ex:HCl, HBr, H 2 S, HF Ex:HCl, HBr, H 2 S, HF Hydro __________ ic Acid Hydro __________ ic Acid

10 Naming Acids (Honors) Ternary Acids Ternary Acids (Contain hydrogen and a polyatomic ion) (Contain hydrogen and a polyatomic ion) Do NOT start with “Hydro” Do NOT start with “Hydro” Look at name of polyatomic ion Look at name of polyatomic ion If it ends in “ate” the acid ends in “ic” If it ends in “ate” the acid ends in “ic” If it ends in “ite” the acid ends in “ous” If it ends in “ite” the acid ends in “ous”

11 Name These Acids (Honors) HBr HBr HNO 3 HNO 3 H 3 PO 4 H 3 PO 4 HNO 2 HNO 2 H 2 C 2 O 4 H 2 C 2 O 4 HClO HClO HBrO HBrO HClO 4 HClO 4 H 2 S H 2 S HIO 3 HIO 3

12 Name These Acids (Honors) HBr = hydrobromic acid HNO 3 = nitric acid H 3 PO 4 = phosphoric acid HNO 2 = nitrous acid H 2 C 2 O 4 = oxalic acid HClO = hypochlorous acid HBrO = hypobromous acid HClO 4 = perchloric acid H 2 S = hydrosulfuric acid HIO 3 = iodic acid

13 Getting to Know Some Bases

14 Naming Bases All Arrhenius bases contain the hydroxide ion All Arrhenius bases contain the hydroxide ion Name ends in “hydroxide” Name ends in “hydroxide” Ex: LiOH = lithium hydroxide Ex: LiOH = lithium hydroxide Note: Note: There are “Non” Arrhenius Bases, more on them later There are “Non” Arrhenius Bases, more on them later

15 15 Some Common Bases See Table L NaOHsodium hydroxide KOH potassium hydroxide Ba(OH) 2 barium hydroxide Mg(OH) 2 magnesium hydroxide Al(OH) 3 aluminum hydroxide

16 Important Note There are no “organic bases” (containing carbon). There are no “organic bases” (containing carbon). C 2 H 5 OH for example is not a base. It is an alcohol. The OH on this molecule does not dissociate to form OH - (hydroxide ion)

17 Salts “Salts” are ionic compounds that are not acids or bases. “Salts” are ionic compounds that are not acids or bases. Metal cation (+) & nonmetal anion (-) Metal cation (+) & nonmetal anion (-) Ex: NaCl, MgSO 4, Li 2 S Ex: NaCl, MgSO 4, Li 2 S

18 18 Learning Check Acid, Base Name Acid, Base Name or Salt CaCl 2 _____________________ KOH_____________________ Ba(OH) 2 ______ _______________ HBr_____________________ H 2 SO 4 ______________________

19 Answers Acid,Base Name or Salt CaCl 2 saltcalcium chloride KOHbasepotassium hydroxide Ba(OH) 2 basebarium hydroxide HClacidhydrochloric acid H 2 SO 4 acidsulfuric acid

20 Electrolytes Acids & Bases & Salts are electrolytes Acids & Bases & Salts are electrolytes Produce free ions when dissolved Produce free ions when dissolved Solutions will conduct. Solutions will conduct. More concentrated = more conductive. More concentrated = more conductive. Do Now: Practice Ditto on Identifying Electrolytes cidsBases/Electrolytes.htm

21 Taste & Feel Acids: taste sour and give a burning sensation if touched Acids: taste sour and give a burning sensation if touched Bases: taste bitter and feel slippery if touched Bases: taste bitter and feel slippery if touched DO NOT attempt to determine an acid or base by taste or touch ever in the lab!

22 Which substance, when dissolved in water, forms a solution that conducts an electric current? Which substance, when dissolved in water, forms a solution that conducts an electric current? (1) C 2 H 5 OH (1) C 2 H 5 OH (3) C 12 H 22 O 11 (2) C 6 H 12 O 6 (3) C 12 H 22 O 11 (2) C 6 H 12 O 6 (4) CH 3 COOH Let’s Review

23 A solid substance was tested in the laboratory. The test results are listed below. dissolves in water is an electrolyte melts at a high temperature Based on these results, the solid substance could be (1) Cu (1) Cu (3) C (2) CuBr 2 (2) CuBr 2 (4) C 6 H 12 O 6

24 The compound HNO 3 can be described as an (1) Arrhenius acid and an electrolyte (2) Arrhenius acid and a nonelectrolyte (3) Arrhenius base and an electrolyte (4) Arrhenius base and a nonelectrolyte

25 Based on Reference Table F, which of these salts is the best electrolyte? Based on Reference Table F, which of these salts is the best electrolyte? A. sodium nitrate B. magnesium carbonate C. silver chloride D. barium sulfate

26 A substance that conducts an electrical current when dissolved in water is called A substance that conducts an electrical current when dissolved in water is called (1) a catalyst (1) a catalyst (2) a non-electrolyte (3) a metalloid (3) a metalloid (4) an electrolyte

27 Which compound is an Arrhenius acid? Which compound is an Arrhenius acid? (1) CaO (1) CaO (2) K 2 O (3) HCl (3) HCl (4) NH 3

28 When one compound dissolves in water, the only positive ion produced in the solution is H 3 O + (aq). This compound is classified as When one compound dissolves in water, the only positive ion produced in the solution is H 3 O + (aq). This compound is classified as (1) a salt (2) a hydrocarbon (3) an Arrhenius acid (4) an Arrhenius base

29 Which substance is an Arrhenius acid? Which substance is an Arrhenius acid? (1) Ba(OH) 2 (1) Ba(OH) 2 (2) H 3 PO 4 (3) CH 3 COOCH 3 (3) CH 3 COOCH 3 (4) NaCl

30 Which compound releases hydroxide ions in an aqueous solution? Which compound releases hydroxide ions in an aqueous solution? (1) CH 3 COOH (1) CH 3 COOH (2) HCl (3) CH 3 OH (3) CH 3 OH (4) KOH

31 An Arrhenius base yields which ion as the only negative ion in an aqueous solution? An Arrhenius base yields which ion as the only negative ion in an aqueous solution? (1) hydride ion (1) hydride ion (2) hydronium ion (3) hydrogen ion (3) hydrogen ion (4) hydroxide ion

32 The compound NaOH(s) dissolves in water to yield The compound NaOH(s) dissolves in water to yield (1) hydroxide ions as the only negative ions (2) hydroxide ions as the only positive ions (3) hydronium ions as the only negative ions (4) hydronium ions as the only positive ions

33 How are HNO 3 (aq) and CH 3 COOH(aq) similar? (1) They are Arrhenius acids and they turn blue litmus red. (2) They are Arrhenius acids and they turn red litmus blue. (3) They are Arrhenius bases and they turn blue litmus red. (4) They are Arrhenius bases and they turn red litmus blue.

34 Acids “Corrode” Certain Metals See Reference Table J See Reference Table J Metals above Hydrogen on the table will react with acids to form a salt and H 2 gas Metals above Hydrogen on the table will react with acids to form a salt and H 2 gas Single Replacement Reaction Single Replacement Reaction 2Zn(s) + 2HCl(aq) ZnCl 2 (aq) + H 2 (g)

35 Will an acid react with these metals? If so complete and balance the single replacement reaction. If so complete and balance the single replacement reaction. Mg + HNO 3 Cu + HCl Ca + H 2 SO 4

36 Answers Mg + 2HNO 3 Mg(NO 3 ) 2 + H 2 Cu + HClNo reaction Cu in below hydrogen on Table J Ca + H 2 SO 4 Ca(SO 4 ) + H 2

37 Bases DO NOT corrode metals Bases DO NOT corrode metals Interactive: Interactive: Acid, Bases and Metals BBC (good for Indicators) Acid, Bases and Metals BBC (good for Indicators) _behaviour/acids_bases_metals/activity.shtml _behaviour/acids_bases_metals/activity.shtml _behaviour/acids_bases_metals/activity.shtml _behaviour/acids_bases_metals/activity.shtml DO NOW: Packet page 2 and 3, # 4, #5

38 pH Scale Used to help determine how acidic or basic something is. Used to help determine how acidic or basic something is. pH = 7 Neutral pH = 7 Neutral pH < 7Acidic pH < 7Acidic pH > 7 Basic pH > 7 Basic

39 Acids & Bases Neutralize Each Other H + ion and OH - ions will join together to form neutral water. H + ion and OH - ions will join together to form neutral water. Reaction is slightly exothermic (See Table I) Reaction is slightly exothermic (See Table I) H + (aq) + OH - (aq) → H 2 O (l)

40 Determining if it is an Acid or Base How can you tell if something is acidic or basic? How can you tell if something is acidic or basic?

41 Use an electronic pH meter Use an electronic pH meter

42 Use an indicator such as litmus Use an indicator such as litmus

43 Use pH paper containing universal indicator Use pH paper containing universal indicator

44 Acid/Bases Indicators Using Table M Litmus Litmus pH range for color change pH range for color change (4.5 – 8.3) (4.5 – 8.3) Color change: red to blue Color change: red to blue Phenolphthalein Phenolphthalein pH range for color change pH range for color change (8 - 9) (8 - 9) Color change: colorless to pink Color change: colorless to pink What color would these be if pH = 10? pH = 3?

45 Based on the results of testing colorless solutions with indicators, which solution is most acidic? (1) a solution in which bromthymol blue is blue (2) a solution in which bromcresol green is blue (3) a solution in which phenolphthalein is pink (4) a solution in which methyl orange is red Let’s Review

46 According to Reference Table M, what is the color of the indicator methyl orange in a solution that has a pH of 2? According to Reference Table M, what is the color of the indicator methyl orange in a solution that has a pH of 2? (1) blue (1) blue (2) orange (3) yellow (3) yellow (4) red

47 Which indicator would best distinguish between a solution with a pH of 3.5 and a solution with a pH of 5.5? Which indicator would best distinguish between a solution with a pH of 3.5 and a solution with a pH of 5.5? (1) bromthymol blue (1) bromthymol blue (2) litmus (3) bromcresol green (3) bromcresol green (4) thymol blue

48 Which indicator is blue in a solution that has a pH of 5.6? Which indicator is blue in a solution that has a pH of 5.6? (1) bromcresol green (1) bromcresol green (2) methyl orange (3) bromthymol blue (3) bromthymol blue (4) thymol blue

49 Which indicator is yellow in a solution with a pH of 9.8? Which indicator is yellow in a solution with a pH of 9.8? (1) methyl orange (2) bromcresol green (3) bromthymol blue (3) bromthymol blue (4) thymol blue

50 In which solution will thymol blue indicator appear blue? In which solution will thymol blue indicator appear blue? (1) 0.1 M CH 3 COOH (2) 0.1 M HCl (3) 0.1 M KOH (3) 0.1 M KOH (4) 0.1 M H 2 SO 4

51 Properties of Acids (Summary) þ Produce H + (as H 3 O + ) ions in water þ Electrolytes (conduct in solution) þ Taste sour þ pH is < 7 þ Corrode metals (see Table J) þ React with bases to form salts and water (Neutralization)

52 Properties of Bases (Summary) Produce OH - ions in water Produce OH - ions in water Electrolytes (conduct in solution) Electrolytes (conduct in solution) Taste bitter, chalky Taste bitter, chalky pH is >7 pH is >7 Feel soapy, slippery Feel soapy, slippery React with acids to form salts and water (Neutralization) React with acids to form salts and water (Neutralization)

53 53 Learning Check Describe the solution in each of the following as: 1) acid 2) base or 3)neutral. A. ___soda B. ___soap B. ___soap C. ___coffee D. ___ wine E. ___ water F. ___ grapefruit F. ___ grapefruit

54 54 Solution Describe each solution as: 1) acid 2) base or 3) neutral. A. _1_ soda B. _2_ soap B. _2_ soap C. _2_ coffee D. _1_ wine E. _3_ water F. _1_ grapefruit F. _1_ grapefruit

55 55 Learning Check Identify each as characteristic of an A) acid or B) base ____ 1. Sour taste ____ 2. Produces OH - in aqueous solutions ____ 3. Chalky taste ____ 3. Chalky taste ____ 4. Is an electrolyte ____ 5. Produces H + in aqueous solutions

56 56 Solution 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


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