ACID BASE CHEMISTRY TERMS, ETC. AMPHOTERIC:Subst. acts as either an acid or a base Proton (Acidic p + ): H + ion; the acidic hydrogen(s) present in an acid HNO 3 : one H + H 2 SO 4 : two H + H 3 PO 4 : three H + MONOPROTIC ACID:An acid w/ one H + DIPROTIC ACID:An acid w/ two H + POLYPROTIC ACID:An acid w/ 3 or more H + HYDRONIUM ION: H 2 O (l) + H +1 (aq) > H 3 O +1 (aq) Proton: H + ; a hydrogen w/ characteristics like a proton itself  1 p +, 0 n 0, 0 e -

AcidBASE All acids contain H + ; when in water give solution higher [H + ] All bases contain OH - ; when in water give solution higher [OH - ] Arrhenius

BRONSTAD – LOWRY Acid Any subst. that donates a proton; H + BASE Any subst. that accepts a proton; H + LEWIS Any subst. that accepts an e - pair Any subst. that donates an e - pair

ACIDS BASES Taste sour Turns litmus blue --  red Lowers pH Feels slippery Turns litmus red --  blue Increases pH The stronger the acid the better it is at donating H + STRONG ACIDS HCl ; HBr ; HI ; HNO 3 ; H 2 SO 4 ; HClO 4 H + +Cl - H + +I - 2H + +SO 4 -2

0 714 pH SCALE STRONG ACIDIC STRONG BASIC MILD ACIDIC MILD BASIC WEAK ACIDIC WEAK BASIC NEUTRAL ( ) K w : constant for water, 1* ACID-BASE REACTIONS HCl (aq) + KOH (aq) ---> KCl (aq) + HOH (l) acid base salt water

pH -- pOH -- [H + ] -- [OH - ] CALCULATIONS Formulas to Use Constants K w = 1 *10 –14 pH = -log [H + ] pOH = -log [OH - ] pK w = 14 Rules for LOGS Log 1 = 0 Log 10 exp = exponent [H + ] = 1*10 -pH [OH - ] = 1*10 -pOH

Rules for LOGS

Calculate pH for the following solutions 1) [H + ] = 1 * ) [H + ] = pH = -log (1*10 -9 ) = -(-9) = = 1*10 -3 pH = -log (1*10 -3 ) = -(-3) = 3

3) [H + ] = 3.6 * pH = -log(3.6*10 -2 ) = 1.44 OR-log = 2 pH = 2 – log (3.6) = 2 – 0.56 = 1.44 Find pH & pOH pOH pK w = pH + pOH 14 = pOH pOH = 14 – 1.44 = OR = 2.78* pOH = 13 – log 2.78 = 13 – 0.44 =

If [H + ] is 6.7*10 -9 mol/L, what is the pH? ACIDIC, BASIC, NEUTRAL What is the [OH - ]? What is the pOH? pH = -log(6.7*10 -9 ) = 9 – log 6.7 = 9 – 0.83 = 8.17 BASIC pOH = 14 – 8.17 = 5.83 [OH - ] = 1* Find pH Find pOH Find [OH - ] OR [OH - ] = 1* *10 -9 = 1.49*10 -6

CONJUGATE ACID-BASE PAIRS Acid, loses H +, form conjugate base Base, gains H +, forms conjugate acid acid 1 acid 2 base 2 base 1 CONJUGATE ACID-BASE PAIRS

TITRATIONS Strong Acid + Strong Base  Neutral Strong Acid + Weak Base ---  Acidic Weak Acid + Strong Base ---  Basic Weak Acid + Weak Base ----  ??????? +/- ions of acid not react w/ H 2 O “+” ion of strong acid reacts w/ H 2 O, produces H 3 O + “-” ion of strong base reacts to produce OH - ions Both +/- ions react w/ H 2 O

STRENGTH Strong Acid/Base ionize completely equilibrium lies far to the right HCl > H + + Cl - NaOH -----> Na + + OH - Weak Acid slightly ionize equilibrium lies far to the left HC 2 H 3 O 2 + H 2 O H + + C 2 H 3 O 2 - K a : acid dissociation constant K b : base dissociation constant IONIZATION CONSTANTS

K a acetic acid = 1.8*10 -5 K a nitrous acid = 4.4*10 -4 nitrous acid more ionized in soln BASE NH 3 + H 2 O NH 4 + +OH - K b ammonia = 1.8*10 -5

Find the Missing Part ??? ACID BASE HCN _________ _______ OH -1 HSO 4 -1 ________ _______ C 2 H 3 O 2 -1 _______ C 2 O 4 -2 ______ NH 3 CN -1 H2OH2O SO 4 -2 HC 2 H 3 O 2 HC 2 O 4 -1 NH 4 +1

S.A. S.A. yields weak conjugate base W.A. W.A. yields strong conj. base MONOPROTIC ACIDS pg. 300 Increasing acid strength Increasing base strength K a Acid 1.2*10 -2 HSO *10 -2 HClO 2 7.2*10 -4 HF 1.8*10 -5 HC 2 H 3 O 2 3.5*10 -8 HOCl 5.6* NH * SO * ClO * F * C 2 H 3 O *10 -7 OCl - 1.8*10 -5 NH 3 K b Conj. Base

acid strength conj. base strength Very Strong Very Weak Strong Weak Strong Very Weak Very Strong

Diprotic & Triprotic Acids H 2 CO 3 : 2 acidic protons K a values for each H + K a1 = 4.3*10 -7 K a2 = 5.6* typically weak polyprotic acid K a1 > K a2 > K a3 means???? -each step of dissociation is successively weaker -loss of 2nd & 3rd proton occurs less readily Why???? should not be surprising think in terms of charges, +/- being attracted

S.A. : K a W.A.: K a & smaller Polyprotic acid: K a value lowers w/ each H+ lost Loss of each additional H+ more difficult H 3 PO 4 + H 2 O H 3 O + + H 2 PO 4 - K a1 H 2 PO H 2 O H 3 O + + HPO 4 -2 K a2 HPO H 2 O H 3 O + + PO 4 -3 K a3 K a1 > K a2 > K a S.B.: K b ????

K a : acid dissociation constant HA + H 2 O H 3 O + + A - HNO 3 + H 2 O H 3 O + + NO 3 -

BUFFER -used to control pH level of a soln. -either remove H + or add OH - ions -usually W.A. & conj. Base TITRATION S.A. + W.B > Acidic W.A. + S.B > Basic S.A. + S.B > Neutral W.A. + W.B > ?? more info. S.A > weak conjugate Base W.A > strong conj. Base

Various Ways to Describe Acid Strength Property S.A. W.A. K a valueK a is large K a is small Position of dissociation equilibrium Far to right Far to left Equilibrium [H + ] compared to [HA] o [H + ] [HA] o [H + ]<<[HA] o Strength of conj.base compared to H 2 O A - much weaker acid than H 2 O A - much stronger base than H 2 O

INTERMOLECULAR FORCES Forces that act between diff. molecules Gases: <<< forces, act independently of each other Liquids/Solids: >>>> Forces KEY PTS. Stronger the Force  more difficult to separate atoms/molecules ----  higher melting/boiling pts of subst.

3 MAJOR FORCES Dipole-Dipole London Dispersion Polar Cov. Bonds “net polarity” Weak Force +/- ends of molecules align together Dipole-Dipole London Dispersion Hydrogen Bonding All molecules; behavior due to e - movement w/i subst. Nonpolar molecules form temporary Polarity Weak Force; as mole.wt. Surface Area: > S.A  > Force stronger the molecule held together

Hydrogen Bonding Strong bond Force H bonded to an O, N, or F of one molecule; that H will be attracted to unshared e - pair of O, N, or F of another molecule O H H.. O H H N F Cl.. H H F