1. Chemical Reactions

2. Types of Chemical Reactions Acid-Base Reactions Neutralization Reactions Neutralization Reactions In a reaction involving HCN(aq), a weak acid, and KOH(aq), a strong base, the product is KCN, a strong electrolyte Acid + Base yields water + salt HA + BOH yields H 2 O + BA HCN (aq) + KOH (aq)  H 2 O (l) + KCN (aq)

3. Types of Chemical Reactions Acid-Base Reactions Acid-Carbonate Reactions Acid-Carbonate Reactions Carbonates react with acids to form CO 2, carbon dioxide gas. BCO 3 + HA yields BA + H 2 O + CO 2

4. Acid/Base Indicators Most acids and bases as well as the resulting salt solution are colorless. Most acids and bases as well as the resulting salt solution are colorless. –In order to determine when the reaction is complete, we must use chemical indicators. Chemical Indicators in the case of acid/base reactions are weak acids that have the property of changing colors when going from basic to acidic solutions or vice-versa. Chemical Indicators in the case of acid/base reactions are weak acids that have the property of changing colors when going from basic to acidic solutions or vice-versa. Chemical Indicators Chemical Indicators The most used acid/base indicator is phenolphthalein. The most used acid/base indicator is phenolphthalein.

5. Types of Chemical Reactions Combination Reactions Combination Reactions Synthesis Reactions (combination). A combination reaction is a reaction in which two substances, usually two elements, combine to form a third substance. A + B yields AB

6. Types of Chemical Reactions Combination Reactions Combination Reactions Oxidation-Reduction Reactions Other combination reactions involve compounds as reactants.

7. Crystallization Ions combine to form an ionic compound Ions combine to form an ionic compound A + (aq) + B - (aq)  AB (s) A + (aq) + B - (aq)  AB (s) Mg 2+ (aq) + O 2- (aq)  MgO (s) Mg 2+ (aq) + O 2- (aq)  MgO (s) 2 NH 4 + (aq) + S 2-  (NH 4 ) 2 S (s) 2 NH 4 + (aq) + S 2-  (NH 4 ) 2 S (s)

8. Dissociation An ionic compound is placed in water and dissociates into its ions An ionic compound is placed in water and dissociates into its ions MgF 2(s)  Mg 2+ (aq) + 2 F - (aq) MgF 2(s)  Mg 2+ (aq) + 2 F - (aq) Na 2 CO 3(s)  2 Na + (aq) + CO 3 2- (aq) Na 2 CO 3(s)  2 Na + (aq) + CO 3 2- (aq)

9. Dissociation Return to Lecture

10. Water Solvation of Ions Return to Lecture

13. Neutralization Reaction Neutralization reaction between Acetic Acid (Vinegar) and Baking Soda (Sodium Bicarbonate).