Warm-up What are some properties of acids and bases? According to the Brønsted-Lowry Model, what is the definition of an Acid? A Base? Describe the dissociation of a strong/weak acid. A strong/weak base. Describe the pH scale. What does it mean that the pH scale is logarithmic? What is the type of strong acid in our stomach? 1

Arrhenius Model of Acids and Bases According to the Arrhenius Model: Acids contain _____________________ which then dissociate. Bases contains ____________________ which then dissociate. Acids and bases can _____________ electricity because the ______________. Hydrogen (H+) Hydroxide (OH-) 2

BrØnsted-Lowry Model of Acids and Bases 5b substances that are hydrogen-ion ____________. Base substances that are hydrogen-ion ____________ Donor Acceptor 3

True or False. All Bases with a Group 1 Metal (Alkali Metal) are Strong Bases…

If an Acid is strong its Conjugate Base is ________________________. If a Base is a weak base than its Conjugate Acid is __________________.

HCO3–(aq) + S2–(aq)  HS–(aq) + CO32–(aq) acid base conjugate acid Complete the following Acid Base Conjugate pairs. The Acid is always first. Complete the equation and label the Conjugate Base (CB) and Conjugate Acid (CA). a) HCO3–(aq) + S2–(aq)  HS–(aq) + CO32–(aq) acid base conjugate acid conjugate base conjugate acid-base pairs b) H2CO3(aq) + OH –(aq)  HCO3–(aq) + H2O(l) acid base conjugate base conjugate acid conjugate acid-base pairs 6

H3O+(aq) + HSO3–(aq)  H2O(l) + H2SO3(aq) acid base conjugate base Complete the following Acid Base Conjugate pairs. Complete the equation and label the Conjugate Base (CB) and Conjugate Acid (CA). c) H3O+(aq) + HSO3–(aq)  H2O(l) + H2SO3(aq) acid base conjugate base conjugate acid conjugate acid-base pairs d) HSO3–(aq) + OH –(aq) + )  H2O(l) + SO32–(aq) base acid conjugate acid conjugate base conjugate acid-base pairs 7

Water as an Acid and a Base Water is _____________, because it can behave as either an acid or as a base 8

What is the formula for finding the concentration of H+ and OH- 9

Strong acid – completely ionized or completely dissociated Weak acid – most of the acid molecules remains intact 10

Acid Strength A strong acid contains a relatively weak conjugate base. Common strong acids are Sulfuric acid, H2SO4 Hydrochloric acid, HCl Nitric acid, HNO3 Perchloric acid, HClO4 Oxyacid – Strong Acids, acidic proton is attached to an oxygen atom 11

pH Scale 5d pH is a measure of how much H+ a solution contains. Describe the pH scale. What does it mean that the pH scale is logarithmic? pH Scale 5d pH is a measure of how much H+ a solution contains. Lower pH contain more H + and less OH- Higher pH contain less H + and more OH- The scale is logarithmic, meaning an increase of 1 on the scale is actually a 10x increase! A pH of 2 is actually 100x as acidic as a 4. 12

The pH Scale pOH scale pOH = log [OH] pH + pOH = 14.00 13

Measuring pH Indicators – substances that exhibit different colors in acidic and basic solutions In an acid solution the indicator will be in the HIn form. In a basic solution the indicator will be in the In form. Other methods Indicator paper pH meter 14

You Try #2 Calculate pH for a solution that has [OH-] = 1.0 x 10-5 M.

You Try #3 Calculate pOH for a solution that has [H+] = 1.0 M

You Try #4 Calculate pOH for a solution that has a pH = 6 pOH = 8

You Try #5 Calculate pH for a solution that has a pOH = 7 pH = 7

You Try #6 Calculate pH for a solution that has a pOH = 7.56 pH = 6.44

You Try #7 Calculate [OH-] for a solution that has a pH = 6.20 pH = 1.6 x 10-8

You Try #8 Calculate [OH-] for a solution that has a pH = 8.20 pH = 1.6 x 10-6

You Try #9 Calculate pH for a solution that has a [OH-] = 2.3 x 10-5

Buffers 5g Buffers are substances that absorb or release H+ as needed to regulate the pH. You have a buffer in your blood called bicarbonate If the pH falls, it absorbs the extra H+ If the pH rises, it releases some H+ It keeps your blood neutral! H2CO3 H+ + HCO3- 23

Neutralization Reactions Both produce Salts when reacted with each other Neutralization reaction: An acid and a base react to form a salt and water. Salt: any ionic compound (metal & non-metal) HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) ACID BASE SALT 24

Salts Made up of a metal and a nonmetal. When dissolved in water, salts conduct electricity. 25

Acid-Base Titrations Titration – delivering a measured volume of a solution of known concentration into the solution being analyzed Buret – device used for accurate measurement of the delivery of a liquid Equivalence Point) – the point at which neutralization occurs. 26

Neutralization Practice MaVa = MbVb Determine the volume of 0.100 M NaOH needed to titrate 50.0mL of 0.200 M HNO3 We need equals moles of H+ and OH- HNO3 is a strong acid --> H+ NaOH is a strong base --> OH- So…we get 0.0500L x 0.200 M H+ = Vol x 0.100 M OH- Volume = 0.100L or 100 ml NaOH

Neutralization Practice #1 (Your Turn) MaVa = MbVb Determine the volume of 0.250 M KOH needed to titrate 25.0mL of 0.150 M HCl We need equals moles of H+ and OH- Volume = 15.0 ml or 0.0150 L KOH

Neutralization Practice #2 (Your Turn) MaVa = MbVb Determine the volume of 0.200 M NaOH needed to titrate 75.0mL of 0.250 M HNO3 Volume = 93.8 ml or 0.0938 L KOH