Unit 12 ~ Acid/Base (Chapter 16) And you

12-1 Introduction and Definitions (Section 16.1) Hydrogen, the simplest element, consists of a proton and an electron. If you remove the electron from an H atom, only the proton remains. Our symbol for a proton is: H+

Several definitions for Acids and Bases exist and are attributed to chemists. Each definition proves useful in describing the acid/base character of certain substances. Arrhenius Definition: Acid is a substance that produces H+ in aqueous solutions. Base is a substance that produces OH- in aqueous solutions.  HCl(aq) → H+ + Cl- NaOH(aq) → Na+ + OH- Brønsted-Lowry Definition: Acid is a substance that donates a proton (H+). Base is a substance that accepts a proton (H+).  HCl → H+ + Cl- NH3 + H+ → NH4+ Lewis Definition: Need to take Chem2 (the coolest class ever) for this one.

Properties of Acids and Bases: Taste: Acids sour (vinegar, OJ, wine, aspirin) Bases bitter (coffee, cigarettes, tonic water, baking soda, antacids, soap) Feel: Acids sting, Bases slippery Acids react with active metals. Zn + 2HCl → ZnCl2 + H2 Bases generally do not react with metals. Solutions of both acids and bases are excellent conductors of electricity (ions are free to move!).

But wait there is more!!! Indicators are chemicals that turn different colors in acids or bases (different pHs). AciD in litmus = RED basE in litmus = BLUE Acid in phenolphthalein = colorless Base in phenolphthalein = pink

Memorize these Acids/Bases  really!!!!!!!! HCl = Hydrochloric acid H2SO4 = Sulfuric acid HNO3 = Nitric acid CH3COOH = Acetic acid (or HC2H3O2) H2O = water Yes water can behave as an acid

Bases: NH3 = Ammonia (covalent) KOH = potassium hydroxide (ionic) NaOH = sodium hydroxide (ionic) H2O = water Yes water can behave as a base

Water can act as either an acid or a base (amphoteric)!

12-2 Conjugate Acid/Base Pairs (Section 16.1) To illustrate the idea of “conjugates”, let’s look at the reaction of hydrochloric acid with water and the Brønsted-Lowry definition of acids as H+ donors and bases as H+ acceptors: HCl + H2O → Cl- + H3O+ acid base conjugate conjugate base acid H+ H+

* conj. Base = what is left of acid after H+ donation * conj. Acid = base + proton (H+) HCl + H2O  H3O+ + Cl- (a) (b) (conj acid) (conj base) H+ ion hooks up with H2O here forms hydronium ion (H3O+)

Practice: HNO3 + NH3 → H+ NO3_ + NH4+ a b Cb Ca WELL DONE!!!!!!!!!!!

WELL DONE!!!!!! Practice: H2O + H2O → Amphoteric: H+ H3O+ + OH- a b Ca Cb WELL DONE!!!!!!