Properties Arrhenius Acids and Bases Naming acids and

- Properties - Arrhenius Acids and Bases - Naming acids and bases Mr. Shields Regents Chemistry U 15 L 01 1

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 Antacids What kind of properties do These substances exhibit? Acids Bases 2

Properties Acids Taste Sour Feel like water React w/ bases to form water & salt (neutralization) React with metals to produce H 2 & salt (Table J) Good electrolytes n i. e ionizes & conducts electricity in solution Acids turn litmus red n What color is the paper? Phenolphthalein turns colorless Bases Taste Bitter Feel slippery React with acids to form water & salt (neutralization) Won’t react with metals Good electrolytes Bases turn litmus blue n What color is the paper? Phenolphthalein turns pink 3

Reaction with Metals OK. So …What metals will react with acids? See Table J to figure this out All the metals above H 2 will react with acids. Cu, Ag, and Au do not react with acids. 4

Example: 2 HCl + Mg Mg. Cl 2 + H 2 (a salt) üMg is above H 2 in Table J so this reaction proceeds as indicated. What kind of rxn is this? üSingle replacement (why) Mg replaces H What kind of rxn is this üRedox (why? ) 2 H+ +2 e- H 20 (red. ) Mg 0 Mg+2 +2 e- (ox. ) 5

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

Neutralization Reactions Acid + Base Salt + Water A Double Replacement Reaction HCl + Na. OH Na. Cl + HOH This is Not Redox (How do I know? ) What kind of reaction is this? 7

Neutralization Acid + Base Salt + Water HCl(aq) + Na. OH(aq) Na. Cl(aq) + H 2 O(l) What is the Ionic Equation for the above rxn? H+(aq) +Cl-(aq) +Na+(aq) +OH-(aq) H 2 O(l) +Na+ (aq) + Cl-(aq) This works because H+ + OH- H 2 O (a Molecule) (one of the ways double replacement goes to completion) Which ions are the spectator Ions? Na+ and Cl- are spectator ions 8

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 9

Arrhenius Theory - According to Arrhenius, Acids are compounds that contain hydrogen and ionizes in water to yield hydrogen ions (H+) Examples: HCl + H 2 O H+ (aq) + Cl-(aq) H 2 SO 4 + H 2 O 2 H+ (aq) + SO 42 - (aq) 10

Arrhenius Theory Take out your Reference Tables. Look at 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 11

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 = ? Hydrofluoric acid HI = ? Hydroiodic acid HCl = ? Hydrochloric acid 12

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 NO 2 - is nitrite HNO 2 is nitrous acid Replace –ate with –ic plus acid NO 3 - is nitrate HNO 3 is nitric acid 13

Ternary Acids For polyatomics with S and P, the stem becomes long again. H 3 PO 4 = phosphoric acid, not phosphic acid H 2 SO 4 = sulfuric acid, not sulfic acid H 2 SO 3 = sulfurous acid, not sulfous acid 14

Kinds of Acids can produce one or more protons (H+) When dissolved in water. -Acids that release one H+ are called MONOPROTIC example: HCL + H 20 H+ + Cl- Acids that release two H+ are called DIPROTIC example: H 2 SO 4 + H 20 2 H+ + SO 4 -2 15

Kinds of Acids - Acids that release three H+ are called TRIPROTIC example: H 3 PO 4 + H 20 3 H+ + PO 4 -3 Notice Table K also lists CH 3 COOH (acetic acid) - this is an “organic” acid - It has only one ionizable H+ (i. e monoprotic) CH 3 COOH + H 20 CH 3 COO- + H+ The ion CH 3 COO- is known as the Acetate Ion 16

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? : HNO 3 H 3 PO 4 HNO 2 H 2 SO 4 HI H 2 CO 3 H 2 SO 3 CH 3 COOH 17

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

Arrhenius Bases According to Arrhenius a base is a compound That ionizes in water to yield HYDROXIDE (OH-) Example: Na. OH + H 20 Na+ + OH- Table L list some of the More common bases. All of these bases are Arrhenius bases except NH 3. We’ll discuss NH 3 Later. 19

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

Problem: Correctly identify which pair is an Arrhenius acid and Arrhenius base: HCl and Na. Cl H 3 PO 4 and Ca(OH)2 H 2 CO 3 and CO 2 HNO 3 and NH 3 H 3 PO 4 and Ca(OH)2 are the correct choice because phosphoric acid donates H+ and Ca(OH)2 because it donates OH 21

Base preparation Group 1 metals react vigorously with water to produce hydroxides Remember the reactions we did in class? 2 Li + 2 H 20 2 Li. OH + H 2 Fast Reactions 2 K + 2 H 20 2 KOH + H 2 2 Na + 2 H 20 2 Na. OH + H 2 Group 1 hydroxides are VERY SOLUABLE in water 22

Base preparation Group 2 metals react less vigorously than Group 1 metals with water. Ca + 2 H 20 Ca(OH)2 + H 2 Mg + 2 H 20 Mg(OH)2 + H 2 Group 2 hydroxides are only very slightly soluble in water. Ca(OH)2 = 0. 165 g/100 ml Mg(OH)2 = 0. 0009 g/100 ml Suspended in water this is known as Milk of Magnesia 23

Acid/Basic Oxides Metal and non-metal oxides when dissolved in water form acids and bases. Non-metal oxides produce acids CO 2 + H 20 H 2 CO 3 Metal oxides produce bases K 20 + H 20 2 KOH 24