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 + H 2 O  ______ + ______ sourlemons metals H+H+ H3O+H3O+ hydronium H+H+ donor Cl − H3O+H3O+

Examples of Common Acids: Pepsi, _________ juices, ___________, stomach acid, battery acid, _____________, ______ citrusaspirin vinegarDNA

Acid Vocabulary monoprotic acid- contains ____ [H + ] ion in its formula Examples: _______, ________ diprotic acid- contains _____ [H + ] ions in its formula Examples: _______, ________ triprotic acid- contains _____ [H + ] ions in its formula Examples: _______, ________ strong acid - readily ___________ to produce ______ [H + ] ions in water Examples: _________, HNO 3, _______ weak acid - produces a __________ amount of [H + ] ions when in water Examples: HC 2 H 3 O 2 (vinegar), _________, _________ 1 HCl HNO 3 2 H 2 SO 4 H 2 CO 3 3 H 3 PO 4 H 3 BO 3 dissociatemany HCl H 2 SO 4 small H 2 CO 3 lemon juice

Strong Acids vs. Weak 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

pH Paper : Indicator Colors Acidic Basic Neutral

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: NH 3 + H 2 O  ______ + _______ bitterbanana slipperysoap OH − acceptor NH 4 + OH −

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

Common Bases Examples of Common Bases: milk of magnesia, ___________, drain cleaner, soap, blood, ____________ tablets, ___________ ________. ammonia antacidbaking 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: ___________, ____________ dissociatemany KOH small NH 3 Alkaline Amphoteric H2OH2OHCO 3 −

Conjugate Acid-Base Pairs Conjugate ______- substance formed when a _______ gains a [H + ] ion. Conjugate ______- substance formed when an ______ loses a [H + ] ion. Practice Problems: Label the acid & base on the left side of the reaction and the conjugate acid & conjugate base on the right side. a) HCl + H 2 O  H 3 O + + Cl − ______ ______ ______ ______ b) NH 3 + H 2 O  NH OH − _____ ______ ______ ______ Acidbase Baseacid baseC.A.C.B. baseacidC.A.C.B.

Self-Ionization of Water Pure water is _____________. It can ionize itself to form OH − and H 3 O + ions in __________ amounts. H 2 O + H 2 O  H 3 O + + OH − (or H 2 O  _______ + _______ ) The universal indicator color is ___________ in neutral solutions. neutral small H+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 pHconcentration pOHOH − below above =

Practice Problems: 1) a) Calculate the pH of a M HCl solution b) What is the pOH of this solution? c) What is the concentration of [OH − ] ions in the solution? 2) a) Calculate the pOH of a NaOH solution that has a pH of 8.50 b) What is the [OH − ] of this solution? c) What is the concentration of [H + ] ions in the solution? [H + ] = MSo…pH = − (log M)pH = 3 pH + pOH = 14So…14 − 3 = pOHpOH = 11 [OH − ] = 10 −pOH [OH − ] = 10 −11 Molar or 1 x 10 −11 M So…14 − 8.5 = pOHpH + pOH = 14 [OH − ] = 10 −5.5 Molar or 3.16 x 10 −6 M[OH − ] = 10 −pOH [H + ] = 10 −pH [H + ] = 10 −8.5 Molar or 3.16 x 10 −9 M pOH = 5.5

pH Testing

Alkalinity Testing

Neutralization 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. HX + M(OH)  ______ + ______ salt water neutral double MX H2OH2O (“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

Practice Problems: (1) Complete the following neutralization reactions. HNO 3 (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 HNO 3 will it take to neutralize 3.0 moles of KOH? KNO 3 H2OH2O CaCl 2 H2OH2O −1−1 2 moles HCl 1 mole Ca(OH) moles HCl x= 0.25 moles of Ca(OH) 2 1 mole KOH 1 mole HNO moles KOH x= 3.0 moles of HNO 3

(M acid )x(V acid ) = (M base )x(V base ) Practice Problems: (1)A 25 mL solution of HNO 3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO 3 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? Determining the Concentration of an Acid (or Base) by Titration ( ) x ( ) = ( ) x ( ) M acid 25 mL1.0 M18 mL M acid = 0.72 Molar 0.76 M55 mL2.0 MV base V base = 20.9 mL