1. 15-1 What are Acids & Bases?  Properties of acids & Bases CharacteristicAcidsBases Phys. StateLiquid / gasSolid Taste / FeelTart, sour, sharpSlippery Electrolyte?Yes ReactionsH 2 O, Metals*H 2 O, fats/oils ProductsH 3 O +**, H +, H 2(g) OH -, soap ArrheniusInc. [H 3 O + ] in H 2 OInc. [OH - ] in H 2 O Bronsted-LowryDonates proton (H + )Accepts proton (H + ) *above H in activity series ** hydronium ion Strong Acids / Bases – completely ionize in soln Weak Acids/Bases – only a fraction of molecule ionizes in soln

2.  1890 – Svante Arrhenius (Swedish) proposed that acids were substances that increased the hydronium ion (H 3 O + ) conc. in H 2 O Bases increased hydroxide ion (OH - ) conc. in water Limited to aqueous solns Could not classify amphoteric substances (chemicals that can act as both an acid & a base)  1923 – Johannes Bronsted (Danish) / Thomas Lowry (British) Proposed that acids were any chemical that donated a proton (H +, a hydrogen atom w/o electron) Bases were any chemical that accepted a H +

3. All Arrhenius acids are Bronsted-Lowry acids, all Arrhenius bases are B-L bases Conjugate acid – acid formed when a base gains a H + Conjugate base – base formed when an acid donated a H + p537

4.  Measuring pH Indicators – dyes that turn different colors in solns of different pH ○ Examples: phenolphthalein, thymol blue… ○ Universal indicator is a mixture of diff indicators ○ pH paper contains several indicators that can develop a rainbow of colors pH meter ○ Electronic instrument w/ probe that has an electrode sensitive to H 3 O + ions ○ Measures by voltage drop – converted into a pH reading ○ Precision = ± 0.01 pH

5. 15.2 Acidity, Basicity & pH  pH scale: pH = power of hydrogen (1909, Soren Sorensen) 0 (lowest, most acidic) 7 (neutral [H 3 O + ] = [OH - ]) 14 (highest, most basic)

6. pH Calculations: K w = [H 3 O + ] [OH - ] = 1.0 x 10 -14 ○ K w is the self-ionization constant of water pH = -log[H 3 O + ] pOH = -log[OH-] pH + pOH = 14 [H 3 O + ] = 10 -pH [OH - ] = 10 -pOH

7. 15-3 Neutralization & Titrations Neutralization Rxn (a.k.a acid-base rxn) – rxn when the ions of acids & bases react to form H 2 O & salt ○ HCl + NaOH  NaCl + H 2 O Titration – method used to det. The conc. Of a substance by adding a soln of a known conc. & vol until rxn is complete – indicated by a change in color Equivalence Point – point at which an acid-base rxn is complete; point at which moles of acid = moles of base Titrant – soln added in titration Standard soln – soln of known conc. End point – point at which the indicator changes color / end of titration ○ want end-point & equivalence point to be the same! Use M 1 V 1 = M 2 V 2 to calculate the concentration of an unknown