Acids and BasesAcids and Bases

Acid PropertiesAcid Properties• Sour taste (citrus fruits)Sour taste (citrus fruits)• Conduct electric currentConduct electric current• Change the color of indicatorsChange the color of indicators

• React with bases to produce salt and React with bases to produce salt and water: water: HCl + NaOH HCl + NaOH H H22O + NaClO + NaCl

• Some react with metals to release HSome react with metals to release H22 gas: gas:Mg + 2HCl Mg + 2HCl MgCl MgCl22 + H + H22

Naming Acids ReviewNaming Acids Review• Binary Acids:Binary Acids:

– Hydroiodic AcidHydroiodic Acid•HIHI

– HFHF•Hydrofluoric Hydrofluoric

Acid Acid

•Ternary Acids (oxyacids)

•HClO4

•Perchloric Acid

•HClO3

•Chloric Acid

•HClO2

•Chlorous Acid•HClO

•Hypochlorius Acid

Base PropertiesBase Properties

• Bitter taste (coffee)Bitter taste (coffee)• Feel slippery (soap)Feel slippery (soap)• Change the color of indicatorsChange the color of indicators• Caustic- attack the skin, cause severe Caustic- attack the skin, cause severe

burnsburns• Conduct electric currentConduct electric current

Arrhenius Acids and BasesArrhenius Acids and Bases•Arrhenius AcidArrhenius Acid: : A compound that produces HA compound that produces H++ in solution. in solution.

Ex:Ex: HHCl (g) + HCl (g) + H22O--------O-------- HH33OO++ (aq) + Cl (aq) + Cl- - (aq)(aq)

•Arrhenius BaseArrhenius Base: : A compound that produces OHA compound that produces OH-- in solution. in solution.

Ex: NaEx: NaOHOH (s) --------- (s) --------- Na Na++ (aq) + (aq) + OHOH-- (aq) (aq)

H2O

Acid/Base StrengthAcid/Base Strength• Strong AcidStrong Acid: Ionizes completely in aq. soln.: Ionizes completely in aq. soln.

HCl H2SO4 HBr HNO3 HI HClO4

Strong Bases: Group 1 and 2 hydroxides

Acid-Base TheoriesAcid-Base Theories• Bronsted-LowryBronsted-Lowry: expands Arrhenius : expands Arrhenius

definition of acids and bases. definition of acids and bases. – Bronsted-Lowry AcidBronsted-Lowry Acid: proton donor: proton donor– Bronsted-Lowry BaseBronsted-Lowry Base: proton acceptor: proton acceptor

ex:ex: HClHCl + + NHNH33 NH NH44++ + Cl + Cl--

Monoprotic B-L Acid

B-L Base

ex2: H3PO4 + H2O H3O+ + H2PO4

-

Which is the B-L Acid? B-L Base?

Lewis Acids and BasesLewis Acids and Bases• Based on bonding and structure and include Based on bonding and structure and include

substances that may not include Hydrogen.substances that may not include Hydrogen.– Lewis AcidLewis Acid: electron pair acceptor: electron pair acceptor– Lewis BaseLewis Base: electron pair donor : electron pair donor

ex: ex: BFBF33 (aq) (aq) + + FF-- (aq) (aq) BF BF44

-- (aq) (aq) Draw the dot structure for these substances and Draw the dot structure for these substances and classify as a Lewis Acid or Base. classify as a Lewis Acid or Base.

Lewis Acid

Lewis Base

Conjugate Acids and BasesConjugate Acids and Bases(Based on Bronsted-Lowry (Based on Bronsted-Lowry Classification)Classification)• Conjugate BaseConjugate Base: The substance that : The substance that

remains after an B-L acid has remains after an B-L acid has given upgiven up a a proton (Hproton (H++).).

• Conjugate AcidConjugate Acid: The substance formed : The substance formed when a B-L base has when a B-L base has gainedgained a proton. a proton.

ex: HCl (aq) + H2O (l) Cl- (aq) + H3O+ (aq) Acid Bas

e Conjugate Base

Conjugate Acid

• Table 15.6: The stronger the acid, the weaker its conjugate base. Equilibrium favors weak acid/base formation.

Amphoteric CompoundsAmphoteric Compounds• Can behave as an acid or base, Can behave as an acid or base,

depending on the strength of the depending on the strength of the acid or base with which they acid or base with which they combine.combine.

• Examples:Examples:– WaterWater– AmmoniaAmmonia

Acid ReactionsAcid Reactions• NeutralizationNeutralization: :

HCl (aq) + NaOH(aq) HCl (aq) + NaOH(aq) NaCl (aq) + H NaCl (aq) + H22O (l)O (l)• Acid Formation from Acid AnhydridesAcid Formation from Acid Anhydrides::

SOSO33 (g) (g) + H + H22O (l) O (l) HH22SOSO44 (aq) (aq)

• Base Formation from Basic Anhydrides:Base Formation from Basic Anhydrides: NaNa22O (s)O (s) + H + H22O(l) O(l) 2NaOH 2NaOH

Acid Anhydride Acid Rain

Basic Anhydride

Aqueous Solutions and pHAqueous Solutions and pH• Self Ionization of WaterSelf Ionization of Water

– Water also supplies HWater also supplies H33OO++ and OH and OH-- ions. ions. HH22O (l) + HO (l) + H22O (l) HO (l) H33OO+ + (aq) + OH(aq) + OH- - (aq)(aq)

1.0 x 10-7 MConductivity Experiments show the concentrations of ions at 25 °C:

1.0 x 10-7 M

• Ionization Constant of Water, KIonization Constant of Water, Kww

KKww = [H = [H33OO++][OH][OH--] = [] = [1.0 x 10-7 M][[1.0 x 10-7 M]

Kw = 1.0 x 10-14 M2 Constant at a given temperature

Neutral, Acidic, and Basic Neutral, Acidic, and Basic SolutionsSolutions• Neutral:Neutral:

[H[H3OO++] = [OH] = [OH--]]• Acids:Acids:

[H[H3OO++] > [OH] > [OH--]]• Bases:Bases:

[H[H3OO++] < [OH] < [OH--]]Determine the hydronium and hydroxide ion concentrations in a 1 x 10-5 M HCl solution.

pH ScalepH Scale A more convenient way to A more convenient way to

express acidityexpress acidity

• pH = -log[HpH = -log[H33OO++]]• pOH = -log[OHpOH = -log[OH--]]• pH + pOH = 14.0pH + pOH = 14.0

• Find the pH and pOH of a 1x10Find the pH and pOH of a 1x10-10-10 M solution of acetic M solution of acetic acid. acid.

Indicators and TitrationIndicators and Titration• Acid-Base IndicatorsAcid-Base Indicators: Compounds whose : Compounds whose

colors are sensitive to pH (weak acid or base).colors are sensitive to pH (weak acid or base).• Titration:Titration: Method used to determine an Method used to determine an

unknown concentration of solution (pg.500) unknown concentration of solution (pg.500)

Equivalence PointEquivalence Point• The point at which the 2 solutions The point at which the 2 solutions

used in a titration are present in used in a titration are present in equal amounts.equal amounts.

• End PointEnd Point: The point in a titration : The point in a titration during which an indicator changes during which an indicator changes color. color.

Molarity Determination from Molarity Determination from TitrationTitration• Because moles of acid=moles of base in a Because moles of acid=moles of base in a

titration AND M = moles/Liter, THEN.......titration AND M = moles/Liter, THEN.......

• MMAAVVAA/C/CAA = M = MBBVVBB/C/CBB

• In a titration, 27.4 ml of 0.015 M NaOH is In a titration, 27.4 ml of 0.015 M NaOH is added to a 20.0 ml sample of HCl solution of added to a 20.0 ml sample of HCl solution of unknown concentration. What is the molarity unknown concentration. What is the molarity of the acid solutionof the acid solution