2. Created by C. Ippolito January 2007 Acids, Bases, and Salts Objectives: 1.Distinguish 1.Distinguish among strong, weak, and non electrolytes 2.Compare 2.Compare Arrhenius and Brønsted-Lowry theories 3.Derive 3.Derive ionization constants of acids 4.Describe 4.Describe properties of acids, bases, and salts 5.Explain 5.Explain conjugate acid-base pairs and amphoteric substances

3. Created by C. Ippolito January 2007 Theory of Ionization ElectrolytesElectrolytes –substances that conduct electricity when in aqueous solutions NonelectrolytesNonelectrolytes –substances that do not conduct electricity when in aqueous solutions Arrhenius’ Theory of IonizationArrhenius’ Theory of Ionization –electrolytes breakdown into small particles (ion) –the particles conduct current

4. Created by C. Ippolito January 2007 Ionic Electrolytes Disassociation –dissolved ionic solids separate into cations and anions hydrated –each ion is hydrated when it is surrounded by water molecules NaCl(s)  Na + (aq) + Cl - (aq) Na 2 SO 4 (s)  2Na + (aq) + SO 4 - (aq)

5. Created by C. Ippolito January 2007 Covalent Electrolytes IonizationIonization –ions formed by a reaction between water and molecular compounds hydronium cation forms when water gains a H atom molecule losing the H atom forms an anion HC 2 H 3 O 2 (l) + H 2 O  H 3 O +( aq) + C 2 H 3 O 2 - (aq) acetic acid hydronium acetate ion ion

6. Created by C. Ippolito January 2007 Acids and Bases Arrhenius’ AcidArrhenius’ Acid –a substance that releases H + ions in water –forming hydronium ions and an anion HCl(g) + H 2 O(l)  H 3 O + (aq) + Cl - (aq) HNO 3 (l) + H 2 O(l)  H 3 O + (aq) + NO 3 - (aq) H 2 SO4(l) + H 2 O(l)  2H 3 O + (aq) + SO 4 2- (aq) H 2 CO 3 (l) + H 2 O(l)  2H 3 O + (aq) + CO 3 2- (aq) Arrhenius’ BaseArrhenius’ Base –a substance that releases OH - ions in water –forming hydroxide ions and a cation NaOH(s) + H 2 O(l)  Na + (aq) + OH - (aq) Mg(OH) 2 + H 2 O(l)  Mg + (aq) + 2OH - (aq) Ca(OH) 2 + H 2 O(l)  Ca + (aq) + 2OH - (aq)

7. Created by C. Ippolito January 2007 Neutralization Bases mixed with acids result in a reaction known as neutralization. Each compound cancels the effect of the other forming water and a salt.  NaOH  Na + + OH -  HCl  H + + Cl - NaOH + HCl  H 2 O + NaCl

8. Created by C. Ippolito January 2007 Brønsted-Lowry Acids and Bases Operational Definition –based on directly observable properties Conceptual Definition –based on interpretation of observed facts Brønsted-Lowry Theory –acid donates a proton –base accepts a proton

9. Created by C. Ippolito January 2007 Conjugate Acid-Base Pairs any acid base reaction: –one substance donates its most loosely held proton –another substance accepts that proton –substances involved in this proton transfer are known as conjugate pairs or conjugate acid-base pairs HCl + H 2 O ↔ H 3 O + + Cl - HCl is the conjugate acid of the base Cl - H 2 O is the conjugate base of the acid H 3 O + H 3 O + is the conjugate acid of the base H 2 O Cl - is the conjugate base of the acid HCl pair members differ by a proton –in the acid he proton is present (HCl) –in the base the proton is missing (Cl-)

10. Created by C. Ippolito January 2007 Comparing Strengths of Acids and Bases Using conjugate acids and base table (p.565) –stronger acids will donate protons to stronger bases acids will only donate proton to bases BELOW them on the table

11. Created by C. Ippolito January 2007 Amphoteric Substance Amphoteric (Amphiprotic) Substances –can act as either a proton donor or a proton acceptor accept protons from strong acids donate protons to strong acids