1. ENERGY MINOR PHYSICAL SCIENCE TUTORING CENTER EXAM #2 MOVED TO FRIDAY, 10/16 Announcements

2. Gas Forming Reactions Special class of acid-base reactions Combination of double displacement (swap) and decomposition reactions  2HCl + Na 2 CO 3  ? Gas Forming Reactions 2H + + CO 3 2-  H 2 O(l) + CO 2 (g) 2H + + S 2-  H 2 S(g) 2H + + SO 3 2-  H 2 O(l) + SO 2 (g) 2H + + M  M 2+ + H 2 (g)

3. Gas Forming Reactions Vinegar + Baking Soda  CH 3 COOH + NaHCO 3  ? Gas Forming Reactions 2H + + CO 3 2-  H 2 O(l) + CO 2 (g) 2H + + S 2-  H 2 S(g) 2H + + SO 3 2-  H 2 O(l) + SO 2 (g) 2H + + M  M 2+ + H 2 (g)

4. What are the products of the reaction of calcium carbonate with acetic acid? CaCO 3 + CH 3 COOH  1. (CH 3 COO) 2 Ca(aq) + H 2 CO 3 (aq) 2. (CH 3 COO) 2 Ca(aq) + H 2 O(l) + CO 2 (g) 3. (CH 3 COO) 2 CO 3 (aq) + H 2 Ca(aq) 4. (CH 3 COO) 2 Ca(s) + H 2 CO 3 (aq) 5. (CH 3 COO) 2 Ca(s) + H 2 O(l) + CO 2 (g)

5. Oxidation Reduction Reactions REDOX REACTIONS ELECTRON-TRANSFER REACTIONS

6. Oxidation and Reduction Reduction  Gain of electron(s)  Loss of oxygen Oxidation  Loss of electron(s)  Gain of oxygen “Redox”- if something is reduced, something else must be oxidized Example:H 2 + F 2 → 2 HF

7. Oxidation Numbers- Keeping Track of Charges Oxidation #’s help keep track of electrons that are lost or gained by an atom Redox reactions always involve change in oxidation numbers  Reduction= oxidation number decreases  Oxidation= oxidation number increases

8. Rules for determining oxidation numbers 1. Each atom in a pure element has an ox. # of zero. 2. For monoatomic ions, ox.# is the charge on the ion. 3. Fluorine always has an ox. # of -1 in compounds. 4. Cl, Br, and I have an ox. # of -1 in compounds, except when combined with F or O. 5. The ox. # of H is +1 and of O is -2 in compounds  Exception for H: In compounds with metals, H is -1  Exception of O: In peroxides, O 2 2- ion gives O an ox. # of -1 6. The sum of the oxidation numbers for all atoms is equal to the net charge of the molecule.

9. What is the oxidation number of H in H 2 O? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3

10. What is the oxidation number of O in H 2 O? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3

11. What is the oxidation number of N in N 2 ? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3

12. What is the oxidation number of N in NO 2 ? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3

13. What is the oxidation number of N in NO 3 - ? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3

14. What is the oxidation number of O in OF 2 ? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3