Homework 3-8 Acid/Base Reactions

Review of H and the Proton Hydrogen, the simplest element, consists of a ___________ and an ____________. Hydrogen, the simplest element, consists of a ___________ and an ____________. If you remove the electron from an H atom, only the proton remains. If you remove the electron from an H atom, only the proton remains. Our symbol for a proton is: H + Our symbol for a proton is: H +

B. Definitions Brønsted-Lowry Brønsted-Lowry HCl + H 2 O  Cl – + H 3 O + AcidsAcids are proton (H + ) donors. BasesBases are proton (H + ) acceptors. conjugate acid conjugate base baseacid

Example Reactions Which is the acid and which is the base? Which is the acid and which is the base? Which water is the acid and which is the base? Which water is the acid and which is the base? Water can act as either an acid or a base (amphoteric)! Water can act as either an acid or a base (amphoteric)!

Properties of Acids and Bases Taste: Taste: Acids sour (vinegar, OJ, wine, aspirin) Bases bitter (coffee, cigarettes, tonic water, baking soda, antacids, soap) Feel: Acids stingBases slippery Feel: Acids stingBases slippery

Properties continued Acids always react with active metals. Acids always react with active metals. Bases generally do not react with metals. HCl nitric

Properties continued Solutions of both acids and bases are excellent conductors of electricity (ions are free to move!). Solutions of both acids and bases are excellent conductors of electricity (ions are free to move!).

Indicators Indicators are chemicals that turn different colors in acids or bases (different pHs). AciD in litmus = RED, base = bLUE Acid in phenolphthalein = colorless Base in phenolphthalein = pink

Choices for ?’s : A) Acid B) Base C) Both 1) Turns litmus red 1) Turns litmus red Ans: A Ans: A 2) Turns phenolpthalein pink 2) Turns phenolpthalein pink Ans: B Ans: B 3) Tastes bitter 3) Tastes bitter Ans: B Ans: B

Choices for ?’s : A) Acid B) Base C) Both 4) Feels slippery 4) Feels slippery Ans: B Ans: B 5) Solution conducts electricity 5) Solution conducts electricity Ans: C Ans: C 6) Always Reacts with active metals 6) Always Reacts with active metals Ans: A Ans: A

Be able to recognize these as Acids or Bases in a chemical rxn Be able to recognize these as Acids or Bases in a chemical rxn Acids:HCl = Hydrochloric acid Acids:HCl = Hydrochloric acid HNO 3 = Nitric acid CH 3 COOH = Acetic acid (or HC 2 H 3 O 2 ) H 2 O = water Bases:NH 3 = Ammonia (covalent) Bases:NH 3 = Ammonia (covalent) KOH = potassium hydroxide (ionic) NaOH = sodium hydroxide (ionic) H 2 O = water

Recognizing Patterns: Acid-Base Conjugate Pairs always differ by an H + Brønsted-Lowry Brønsted-Lowry HCl + H 2 O  Cl – + H 3 O + AcidsAcids are proton (H + ) donors. BasesBases are proton (H + ) acceptors. conjugate acid conjugate base baseacid

Recognizing Patterns: Conjugate Acid-Base Pairs Cl - NH 3 OH - HCl NH 4 + H2OH2OH2OH2O  Give the conjugate acid for each of the following:

Recognizing Patterns: Conjugate Acid-Base Pairs Cl - NO 3 - C2H3O2-C2H3O2-C2H3O2-C2H3O2-HCl HNO 3 C 2 H 3 O 2 H  Give the conjugate base for each of the following:

Example Reaction NH 3 + HCl → NH 3 + HCl → Video Link Video Link Video Link Video Link HCl + NaOH HCl + NaOH HCl + NaOH HCl + NaOH

Water is amphoteric - can be an acid or a base.  Amphoteric - can be an acid or a base. NH 3 + H 2 O  B A

Water is amphoteric .... NH 3 + H 2 O  NH OH - CACBBA

Water is amphoteric H 2 O + HNO 3  A B

Water is amphoteric H 2 O + HNO 3  H 3 O + + NO 3 – CBCAAB

Ionic Bases: Must dissociate ions first NaOH (aq) + HCl(aq) → NaOH (aq) + HCl(aq) → Ionic base Acid Ionic base Acid Na +1 OH -1 H + Cl - Na +1 OH -1 H + Cl - H 2 O + Na +1 + Cl - or NaCl H 2 O + Na +1 + Cl - or NaCl NaOH (aq) + HCl(aq) → H 2 O + NaCl NaOH (aq) + HCl(aq) → H 2 O + NaCl