Ch. 16 Notes -- Acids and Bases What makes something an acid? Acid Properties: (1) tastes _______-- _______________ (2) corrosive to _________ (3) contains [ ___ ] (or [ _____ ] = “_______________” ions) (4) proton ([ ___ ]) __________-- Brønsted-Lowry Theory Example: HCl + H2O  ______ + ______ sour lemons metals H+ H3O+ hydronium H+ donor H3O+ Cl−

Examples of Common Acids: Pepsi, _________ juices, ___________, stomach acid, battery acid, _____________, ______ citrus aspirin vinegar DNA

Acid Vocabulary strong acid - readily ___________ to produce ______ [H+] ions in water Examples: _________, HNO3, _______ weak acid - produces a __________ amount of [H+] ions when in water Examples: HC2H3O2 (vinegar) , _________, _________ dissociate many H2SO4 HCl small H2CO3 lemon juice

Strong Acids vs. Weak Acids

Indicator Colors For Acids Indicators An indicator is a chemical that will change ___________ when placed in an acidic, basic or neutral environment. Indicator Colors For Acids litmus paper = _______ phenolphthalein = ___________ red cabbage juice (universal indicator) = ________ methyl orange = _______ colors red clear red red

pH Paper : Indicator Colors Neutral Acidic Basic

Properties of Bases What make something a base? Base Properties: (…the opposite of acid properties) (1) tastes ________ -- ___________ peel , parsley, dark chocolate (2) feels _____________ -- ________ (3) contains [ _____ ] ions (4) proton ([H+]) ______________-- Brønsted-Lowry Theory Example: NH3 + H2O  ______ + _______ bitter banana slippery soap OH− acceptor NH4+ OH−

Indicator Colors for Bases litmus paper = _______ methyl orange = ____________ red cabbage juice (universal indicator) =________ phenolphthalein = ______ blue yellow blue pink phenolphthalein Acid Base

Common Bases Examples of Common Bases: milk of magnesia, ___________, drain cleaner, soap, blood, ____________ tablets, ___________ ________. ammonia antacid baking soda

Strong Bases vs. Weak Bases strong base- readily __________ to produce ______ [OH−] ions in water Examples: NaOH , ________ weak base- produces a __________ amount of [OH−] ions when in water Examples: _____ (ammonia); Mg(OH)2 (milk of magnesia) Other Vocabulary _______________- another term for basic solutions _______________- a substance that can act as both an acid and a base Examples: ___________ , ____________ dissociate many KOH small NH3 Alkaline Amphoteric H2O HCO3−

Self-Ionization of Water Pure water is _____________. It can ionize itself to form OH− and H3O+ ions in __________ amounts. H2O + H2O  H3O+ + OH− (or H2O  _______ + _______ ) The universal indicator color is ___________ in neutral solutions. neutral small H+ OH− green self-ionization of water

Measuring the Amount of H+ and OH− Ions in a Solution _____ Scale- measures the _____________ of [H+] ions in a solution _____ Scale- measures the concentration of [ ____ ] ions in a solution Formulas pH = − (log [H+]) pOH = −(log [OH−]) [H+] = 10−pH [OH−] = 10−pOH [H+] x [OH−] = 1 x 10−14 pH + pOH = 14 With the pH scale, we have another way to define acids and bases: Acids have a pH _________7.0 Bases have a pH _________7.0 Neutral pH ___7.0 pH concentration pOH OH− below above =

Practice Problems: 1) a) Calculate the pH of a 0.001 M HCl solution b) Is this an acid or a base? 2) a) What is the concentration of [H+] ions in a solution that has a pH of 8.50? [H+] = 0.001 M So…pH = − (log 0.001 M) pH = 3 Acid! [H+] = 10−pH [H+] = 10−8.5 Molar or 3.16 x 10−9 M Base!

pH Testing

Alkalinity Testing

Neutralization Reactions When an acid and base are mixed, the reaction produces _______ and ___________. If the initial concentrations and volumes of the reactants are equal, the products will be ____________... (pH= 7.0) All neutralization reactions are ___________ replacement reactions. salt water neutral double H2O HX + M(OH)  ______ + ______ MX (“Salt”)

Titration Mixing an acid with a base to determine a __________________ is called “titration.” An ____________ is used to determine when neutralization has occurred. ________________ Solution - the solution of known concentration _________________ - the point of neutralization when titrating At the eqivalence point, the moles of [H+] ions = moles of [OH−] ions. The “_____ Point” is when the indicator changes color. concentration indicator Standard Equivalence Point End

Titration Curve

(1) Complete the following neutralization reactions. Practice Problems: (1) Complete the following neutralization reactions. HNO3 (aq) + KOH (aq)  _________ + __________ HCl (aq) + Ca(OH)2 (aq)  __________ + ___________ (2) How many moles of Ca(OH)2 will it take to neutralize 0.5 moles of HCl? 3) How many moles of HNO3 will it take to neutralize 3.0 moles of KOH? KNO3 H2O +2 −1 CaCl2 H2O 2 2 1 mole Ca(OH)2 0.5 moles HCl 0.25 moles of Ca(OH)2 x = 2 moles HCl 1 mole HNO3 3.0 moles KOH 3.0 moles of HNO3 x = 1 mole KOH

Determining the Concentration of an Acid (or Base) by Titration (Macid)x(Vacid) = (Mbase)x(Vbase) Practice Problems: A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO3 solution? (2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of a 0.76 M HCl standard solution? ( ) x ( ) = ( ) x ( ) Macid 25 mL 1.0 M 18 mL Macid = 0.72 Molar ( ) x ( ) = ( ) x ( ) 0.76 M 55 mL 2.0 M Vbase Vbase = 20.9 mL