1. Take out HW and Stamp Sheet  #’s 20-22,24,32a,34a,35,36  #’s 31a,33a,37,39,40, 48-50,56,58ab 2. Solve this problem: What is the pH of a solution with a pOH of 11.09? 3. HW = pH problem set due Mon & study for quiz

14 1 x x x x x x x x x x x x x x x x x x x x x x x x x x x x NaOH, 0.1 M Household bleach Household ammonia Lime water Milk of magnesia Borax Baking soda Egg white, seawater Human blood, tears Milk Saliva Rain Black coffee Banana Tomatoes Wine Cola, vinegar Lemon juice Gastric juice More basic More acidic pH [H 1+ ] [OH 1- ] pOH 7 1 x x

pH pOH [H 3 O + ] [OH - ] pH + pOH = 14 pH = -log[H 3 O + ] [H 3 O + ] = 10 -pH pOH = -log[OH - ] [OH - ] = 10 -pOH K w = [H 3 O + ] [OH - ] = 1 x10 -14

pH + pOH = 14 pH = 14 Solution is acidic pH = 14 – = 2.91

Solution is basic K w = [H 3 O + ] [OH - ] = 1.0 x x = [3.3 x ] [OH - ] [OH - ] = 3.0 x M

pH pOH [H 3 O + ] [OH - ] pH + pOH = 14 pH = -log[H 3 O + ] [H 3 O + ] = 10 -pH pOH = -log[OH - ] [OH - ] = 10 -pOH K w = [H 3 O + ] [OH - ] = 1 x10 -14

OH - H3O+H3O+ H3O+H3O+ H3O+H3O+ [H 3 O + ] = [OH - ] [H 3 O + ] > [OH - ] [H 3 O + ] < [OH - ] acidic solution neutral solution basic solution concentration (moles/L)‏ Timberlake, Chemistry 7 th Edition, page 332 pH = 3 pH = 7 pH = 11

0.120 M H 2 SO 4 2 mol H 3 O + 1 mol H 2 SO 4 X = M H 3 O + pH = - log [H 3 O + ] = -log [0.240M H 3 O + ] pH = 0.620

pH pOH [H 3 O + ] [OH - ] pH + pOH = 14 pH = -log[H 3 O + ] [H 3 O + ] = 10 -pH pOH = -log[OH - ] [OH - ] = 10 -pOH K w = [H 3 O + ] [OH - ] = 1 x10 -14

pH = - log [H 3 O + ] 4.60 = -log [H 3 O + ] [H 3 O + ] = 2.51 x M 2 nd log -4.6 You can check your answer by working backwards. pH = - log [2.51x10 -5 M] pH =

pH pOH [H 3 O + ] [OH - ] pH + pOH = 14 pH = -log[H 3 O + ] [H 3 O + ] = 10 -pH pOH = -log[OH - ] [OH - ] = 10 -pOH K w = [H 3 O + ] [OH - ] = 1 x10 -14

 Definition ◦ Analytical method in which a standard solution is used to determine the concentration of an unknown solution. standard solution unknown solution Courtesy Christy Johannesson

Buret stopcock Erlenmeyer flask

 Titrant ◦ The substance added to the analyte in a titration (a standard solution)  Analyte ◦ The substance being analyzed  Equivalence point ◦ The point in a titration at which the quantity of titrant is exactly sufficient for stoichiometric reaction with the analyte.

Titrant Analyte If the concentration of the titrant is known, then the unknown concentration of the analyte can be determined.

Quantitative analysis — used to determine the amounts or concentrations of substances present in a sample by using a combination of chemical reactions and stoichiometric calculations

 The “perfect pink” for a titration with phenolphthalein

Indicator - changes color to indicate pH change Volume base added Example… phenolphthalein is colorless in acid and pink in basic solution pH Endpoint = 7 pink point at which exactly enough reactant has been added for the solution to be neutralized and no more

◦ Point at which equal amounts of H 3 O + and OH - have been added. ◦ Determined by…  indicator color change  dramatic change in pH Courtesy Christy Johannesson

moles H 3 O + = moles OH - Courtesy Christy Johannesson

 25.5 mL of 1.3M KOH are required to neutralize 50.0 mL of HCl. Find the molarity of HCl. Acid (H 3 O + ) M = ? V = 50.0 mL Base (OH - ) M = 1.3M V = 25.5 mL M A = 0.66M HCl Courtesy Christy Johannesson

equivalence point pH Volume of M NaOH added (mL) Titration of an Acid With an Base NaOH added (mL) pH Titration Data Solution of NaOH Solution of NaOH Solution of HCl H+H+ H+H+ H+H+ H+H+ Cl - Na + OH - 25 mL phenolphthalein - colorless phenolphthalein - pink

Arrhenius - In aqueous solution… Arrhenius - In aqueous solution… HCl (aq)  H + (aq) + Cl- (aq) Acids Acids increase hydrogen ion concentration [H + ] H HHHH H Cl OO – + Courtesy Christy Johannesson

A Brønsted-Lowry acid is a proton donor A Brønsted-Lowry base is a proton acceptor acid conjugate base base conjugate acid

 From the Latin word conjugare, meaning “to join together.”  Reactions between acids and bases always yield their conjugate bases and acids.

HNO 3, HCl, H 2 SO 4 and HClO 4 are among the only known strong acids. Strong and Weak Acids/Bases The strength of an acid (or base) is determined by the amount of IONIZATION.

 Weak acids are much less than 100% ionized in water. One of the best known is acetic acid = CH 3 CO 2 H Strong and Weak Acids/Bases

 Strong Base: 100% dissociated in water. NaOH (aq) ---> Na + (aq) + OH - (aq) Strong and Weak Acids/Bases Other common strong bases include KOH and Ca(OH) 2. CaO (lime) + H 2 O --> Ca(OH) 2 (slaked lime) Ca(OH) 2 (slaked lime) CaO

 Weak base: less than 100% ionized in water One of the best known weak bases is ammonia NH 3 (aq) + H 2 O (l)  NH 4 + (aq) + OH - (aq) Strong and Weak Acids/Bases

 The more polar the H-X bond and/or the weaker the H-X bond, the more acidic the compound.  Acidity increases from left to right across a row and from top to bottom down a group.

H 2 O can function as both an ACID and a BASE. Equilibrium constant for water = K w K w = [H 3 O + ] [OH - ] = 1.00 x at 25 o C

Timberlake, Chemistry 7 th Edition, page M HCl 0 gastric juice 1.6 vinegar 2.8 carbonated beverage 3.0 orange 3.5 apple juice 3.8 tomato 4.2 lemon juice 2.2 coffee 5.0 bread 5.5 soil 5.5 potato 5.8 urine 6.0 milk 6.4 water (pure) ‏ 7.0 drinking water 7.2 blood 7.4 detergents bile 8.0 seawater 8.5 milk of magnesia 10.5 ammonia 11.0 bleach M NaOH (lye) ‏ acidic neutral basic [H + ] = [OH - ]