2 Acids are proton donors (give a hydrogen away) 1) Sour taste2) Litmus paper (common indicator) changes from blue to red in an acid or red litmus paper stays red.3) Acids always contain hydrogen.Acids are proton donors (give a hydrogen away)Bronsted-Lowry definition of an acid4) Acids react with metals to form hydrogen gasand a metal compound called corrosion
3 HCl(g) + H2O (l) ----- H3O+ (aq) + Cl- (aq) Acids – produce hydronium ions in water.HCl(g) + H2O (l) ----- H3O+ (aq) + Cl- (aq)Also known as Arrhenius AcidsWhen a hydrogen atom is attached to a water molecule. Hydronium ion: H3O+ ion is positively charged.Conduct an electrical current (charged particles).Hydrogen is always written first in an acid.If there is Only one hydrogen – HCl – monoproticDiprotic (2) and polyprotic (more than 2)Example: H2SO4 – sulfuric acid - diprotic
4 Note: if hydrogen is not written first – not an acid! BUT not all hydrogen containing compounds are acids.Example: sugar C11H22 O11Note: if hydrogen is not written first – not an acid!
5 Bases1) taste bitter, feel slippery2) turn litmus paper from red to blue or blue paper stays blue.3) emulsify (dissolve) fats and oilsArrhenius bases produce hydroxide ion (OH-) when dissolved in water. (need to know name and symbol)5) Bases are called proton acceptorsProton acceptors- Bronsted – Lowry definition of a base
6 NaOH (s) ------- Na+ (aq) + OH- (aq) OH- hydroxide ion Common Base - Sodium Hydroxide (NaOH) also known as ‘lye’ common base – very strong.NaOH (s) Na+ (aq) OH- (aq)OH- hydroxide ionExample: NH3 (g) + H2O (l) --- NH4+ (aq) + OH- (aq)Ammonia – covalent baseWater does play a role in this reactionSince NH3 accepts a proton (H+) and is now NH4+ it is considered a base.H2O
7 14.2 Strengths of Acids and Bases Strong Acids and Bases Completely ionize in water
8 Common acids – know these Strong: H2SO4 – sulfuric acid HNO3 – nitric acidHCl – hydrochloric acid– highest production of any acid in the United States. Used in the production of paper, fertilizers, petroleum refining and car batteries.used in the production of rubber, plastics, pharmaceuticals, fertilizers and explosivesused in the pickling of steel, used to purify magnesium from sea water, correct swimming pool pH, found in your gastric juices (aids in the digestion of proteins) Sold commerically as “Muriatic Acid”
9 Strong acids :ionize well in water (lose hydrogen quickly) = good electrolytes
10 Weak acids:HC2H3O2 – acetic acid (acid in vinegar) know this oneH2CO3 – carbonic acid (used for carbonating soda)H3PO4 – phosphoric acid (a flavoring agent in soda)H3BO3 – boric acid (eye wash)Weak acids do not ionize well in solution (produce only a few H+ in solution)Poor Electrolytes!Acetic acid
11 Common Bases –Strong bases ionizes completely in water, produce large # of ions therefore Good Electrolytes.Strong Bases:KOH – battery electrolyteNaOH – used for making soap, Drano; know this oneCa(OH)2 – leather production, making plasterMg(OH)2 – laxative, antacid
12 Weak Bases: do not produce large amount of ions, weak electrolytes. NH4OH – ammonium hydroxide (household cleaner)Al(OH)3 – aluminum hydroxide (antacid, deodorant)NH3 Ammonia – household cleaning productsknow this one
13 pH scale is used to measure the acidity of solution. Definition:The pH (‘potential of hydrogen’) is a measure of hydronium ion (H3O+)concentration.It is a Mathematical scale 0-14.Logarithmic Scale – based on powers of 10.Example: pH of 3 is 10 times more acidic than a pH 4.pH of 3 is 100 (10 x 10) times more acidic than the pH of 5.
14 7 = neutral (distilled water) pH less than 7 = acidicpH above 7 = basic7 = neutral (distilled water)To calculate pH scale = take the negativeof the exponent of thehydronium ion concentration = -log [H3O+]Concentrations of hydronium and hydroxide in water:[H3O+] x [OH-] = 1 xExample: If concentration of the hydronium ion [H3O+] is 10-8 M. Then the solution has a pH of 8.Example: If the hydroxide ion [OH-] concentration is 10-5 M, then the pH = / = pH of 9.
15 pH of common materials showing the relationship between pH and the hydronium ion concentration. Pure water has a pH of 7.0. show demoNormal rain is slightly acidic because carbon dioxide (CO2) dissolves into it forming weak carbonic acid, giving the resulting mixture a pH of approximately 5.6 at typical atmospheric concentrations of CO2.As of 2000, the most acidic rain falling in the U.S. has a pH of about 4.3.
17 15.1 Acid and Base Reactions The reaction between an acid and a base is called a Neutralization Reaction.Usually neutralization reactions produce water and a salt.NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)pH = 7
18 Salt – Ionic compound formed from the negative part of the acid and the positive part of the base. Neutral substance.NaCl is not the only ionic compounds that are salts. Others include: KCl, KBr, NH4NO3
19 Indicators are used to test whether a substance is an acid or a base. Phenolphthalein – common indicator, colorless in an acid; pink in a base.pink in a base.colorless in an acid