Acids and Bases

1. Acids and Bases • - Properties • Arrhenius Acids and Bases • Naming acids and bases Mr. Shields Regents Chemistry U15 L01

2. Acids Bases Properties We’ve all encountered acids and bases in our Daily lives. For example all of these common items are examples Of acids or bases Other examples are: Acid Rain Tea Coke Car batteries Ants Antacids What kind of properties do These substances exhibit?

3. Taste Sour Feel like water React w/ bases to form water & salt (neutralization) React with metals to produce H2 & salt (Table J) Good electrolytes i.e ionizes & conducts electricity in solution Acids turn litmus red What color is the paper? Phenolphthalein turns colorless Taste Bitter Feel slippery React with acids to form water & salt (neutralization) Won’t react with metals Good electrolytes Bases turn litmus blue What color is the paper? Phenolphthalein turns pink PropertiesAcidsBases

4. Reaction with Metals OK. So …What metals will react with acids? • See Table J to figure this out • All the metals above H2 will react with acids. • Cu, Ag, and Audo not react with acids.

5. Example: 2HCl + Mg  MgCl2 + H2 (a salt) • Mg is above H2 in Table J so this reaction proceeds as indicated. What kind of rxn is this? • Single replacement (why) • Redox (why?) Mg replaces H What kind of rxn is this 2H+ +2e-  H20 (red.) Mg0  Mg+2 +2e- (ox.)

6. Problem: Will the following reaction proceed as indicated? 6HCl + 2Au  3H2 + 2AuCl3 No. Gold is below Hydrogen in Table J Problem: Will the following reaction proceed as indicated? 6HCl + 2Co  3H2 + 2CoCl3 Yes. Cobalt is above Hydrogen in Table J

7. Neutralization Reactions • Acid + Base  Salt + Water • A Double Replacement Reaction HCl + NaOH  NaCl + HOH • This is Not Redox (How do I know?) • What kind of reaction is this?

8. Neutralization Acid + Base  Salt + Water HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l) What is the Ionic Equation for the above rxn? H+(aq) +Cl-(aq) +Na+(aq) +OH-(aq)  H2O(l) +Na+ (aq)+Cl-(aq) This works because H+ + OH-  H2O (a Molecule) (one of the ways double replacement goes to completion) Which ions are the spectator Ions? Na+ and Cl- are spectator ions

9. Arrhenius Theory • An early attempt (1884) to explain acids and • bases is known as the Arrhenius Theory. • This was the first successful definition of • what an acid and base is • It was based on what ion is released • when the Compound is dissolved in water

10. Arrhenius Theory - According to Arrhenius, Acids are compounds that contain hydrogen and ionizes in water to yield hydrogen ions (H+) Examples: HCl + H2O  H+ (aq) + Cl-(aq) H2SO4+ H2O  2H+ (aq) + SO42- (aq)

11. Arrhenius Theory Take out your Reference Tables. Look at Table K Table K list the name and formulas of some common acids. ALL of these Acids are Arrhenius acids. They all produce H+ ions in sol’n

12. Naming Binary Acids A binary acid is an acid with only 2 elements. They are named as follows: Hydro + Stem of nonmetal ion + ic (ex. Chloride Chlor) HF = ? HI = ? HCl = ? Hydrofluoric acid Hydroiodic acid Hydrochloric acid

13. Naming Ternary Acids • A Ternary acid is composed of 3 elements. The Name is derived from the polyatomic anion (see Table E) • Replace –ite with –ous plus acid NO2- is nitrite HNO2 is nitrous acid • Replace –ate with –ic plus acid NO3- is nitrate HNO3 is nitric acid

14. Ternary Acids • For polyatomics with S and P, the stem becomes long again. • H3PO4 = phosphoric acid, not phosphic acid • H2SO4 = sulfuric acid, not sulfic acid • H2SO3 = sulfurous acid, not sulfous acid

15. Kinds of Acids • Acids can produce one or more protons (H+) • When dissolved in water. • Acids that release one H+ are called • MONOPROTIC • example: HCL + H20  H+ + Cl- - Acids that release two H+ are called DIPROTIC example: H2SO4 + H20  2H+ + SO4-2

16. Kinds of Acids - Acids that release three H+ are called TRIPROTIC example: H3PO4 + H20  3H+ + PO4-3 Notice Table K also lists CH3COOH (acetic acid) - this is an “organic” acid - It has only one ionizable H+ (i.e monoprotic) CH3COOH + H20  CH3COO- + H+ The ion CH3COO- is known as the AcetateIon

17. Types of Acids • What are the names of the following acids, what Kind of acids are they and how many protons are released when the acid hydolyszed in water?: • HNO3 • H3PO4 • HNO2 • H2SO4 • HI • H2CO3 • H2SO3 • CH3COOH

18. Arrhenius Base • According to Arrhenius an acid is a substance that contains hydrogen and produces H+ in aqueous solutions. • So how did Arrhenius define a base? • A substance that contains hydroxide and produces OH- as the only negative ion in aqueous solution.

19. Arrhenius Bases According to Arrhenius a base is a compound That ionizes in water to yield HYDROXIDE (OH-) Example: NaOH + H20  Na+ + OH- Table L list some of the More common bases. All of these bases are Arrhenius bases except NH3. We’ll discuss NH3 Later.

20. Naming Bases • Naming hydroxides  metal name + hydroxide Monohydroxy • NaOH = ? Dihydroxy • Ca(OH)2 = ? • Mg(OH)2 = ? Trihydroxy • Fe(OH)3 = ? Iron (III) Hydroxide!

21. Problem: • Correctly identify which pair is an Arrhenius acid and Arrhenius base: • HCl and NaCl • H3PO4 and Ca(OH)2 • H2CO3 and CO2 • HNO3 and NH3 • H3PO4 and Ca(OH)2 are the correct choice because phosphoric acid donates H+ and Ca(OH)2 because it donates OH-

22. Base preparation Group 1 metals react vigorously with water to produce hydroxides Remember the reactions we did in class? 2Li + 2H20  2LiOH + H2Fast Reactions 2K + 2H20  2KOH + H2 2Na + 2H20  2NaOH + H2 Group 1 hydroxides are VERY SOLUABLE in water

23. Base preparation Group 2 metals react less vigorously than Group 1 metals with water. Ca + 2H20  Ca(OH)2 + H2 Mg + 2H20  Mg(OH)2 + H2 Group 2 hydroxides are only very slightly soluble in water. Ca(OH)2 = 0.165g/100ml Mg(OH)2 = 0.0009g/100ml  Suspended in water this is known as Milk of Magnesia

24. Acid/Basic Oxides Metal and non-metal oxides when dissolved in water form acids and bases. Non-metal oxides produce acids CO2 + H20  H2CO3 Metal oxides produce bases K20 + H20  2KOH