Unit 18 Acids and Bases

I. Defining Acids & Bases A. Properties Acids Bases 1. Taste sour bitter (not in lab) ex: Citrus ex: soap fruits, yogurt vinegar 2. Touch sting, feel sting eyes (not in lab) like water only, feel smooth, slippery

I. Defining Acids & Bases Properties Acids Bases 3. Reactions React Don’t react w/metals Produce H 2 4. Electrical Electrolyte Electrolyte conductivity 5. Acid-Base blue-red red-blue Indicators One color in acids; another color in bases (litmus)

I. Defining Acids & Bases Properties Acids Bases 6. Neutralization add base add acid (neutral) neutralization reaction forms a salt

B. Definitions of Acids & Bases 1. Arrhenius Definition: An acid is a substance that dissociates in water to produce hydrogen ions (H + ) A base is a substance that dissociates in water to produce hydroxide ions (OH - ) Acids HCl → H + + Cl - HNO 3 → H + + NO 3 - H 2 SO 4 → 2 H + + SO 4 2-

B. Definitions of Acids & Bases Bases NaOH → Na + + OH - KOH → K + + OH - Mg(OH) 2 → Mg OH - Neutralization- acids + bases H + (aq) + OH - (aq) → H 2 O (l) HCl (aq) + NaOH (aq) → H 2 O (l) + NaCl (aq) Acid base water salt

B. Definitions of Acids & Bases HNO 3(aq) + KOH (aq) → H 2 O (l) + KNO 3(aq) Acid base water salt 2HI (aq) + Ca(OH) 2(aq) → H 2 O (l) + CaI 2(aq) Acid base water salt Mg (s) + 2H + (aq) → Mg 2+ (aq) + H 2(g) Metal hydrogen ion metal ion hydrogen gas

B. Definitions of Acids & Bases 2. Bronsted-Lowry Definition: An acid is any substance that can donate H + ions. A base is any substance that can accept H + ions. Advantages: not dependent on water focuses solely on H + ions H + = proton

B. Definitions of Acids & Bases An acid is a proton donor. A base is a proton acceptor. Monoprotic acids: donate one proton (HCl, HNO 3 ) Diprotic acids: donate two protons (H 2 SO 4, H 2 CO 3 ) Triprotic acids: donate three protons (H 3 PO 4 )

B. Definitions of Acids & Bases Hydronium ion: H + + H 2 O → H 3 O + hydronium ion HCl (g) + H 2 O (l) → H 3 O + (aq) + Cl - (aq) NH 3(g) + H 2 O (l) → NH 4 + (aq) + OH - (aq) Amphoteric: substance that can act as either an acid or a base

C. Conjugate Acid-Base Pairs NH 3(g) + H 2 O (l) → NH 4 + (aq) + OH - (aq) Base acid conjugate conjugate acid base NH 3 -- NH 4 + base – conjugate acid H 2 O -- OH - acid – conjugate base HCl acid conjugate base? H 2 SO 4 acid conjugate base?

C. Conjugate Acid-Base Pairs NH 3(g) + H 2 O (l) → NH 4 + (aq) + OH - (aq) Base acid conjugate conjugate acid base NH 3 -- NH 4 + base – conjugate acid H 2 O -- OH - acid – conjugate base HCl acid conjugate base? Cl - H 2 SO 4 acid conjugate base? HSO 4 -