•ENERGY MINOR

•PHYSICAL SCIENCE TUTORING CENTER

•EXAM #2 MOVED TO FRIDAY, 10/16

Announcements

Gas Forming Reactions

Special class of acid-base reactions

Combination of double displacement (swap) and decomposition reactions 2HCl + Na2CO3 ?

Gas Forming Reactions

2H+ + CO32- H2O(l) + CO2(g)

2H+ + S2- H2S(g)

2H+ + SO32- H2O(l) + SO2(g)

2H+ + M M2+ + H2(g)

Gas Forming Reactions

Vinegar + Baking Soda

CH3COOH + NaHCO3 ?

Gas Forming Reactions

2H+ + CO32- H2O(l) + CO2(g)

2H+ + S2- H2S(g)

2H+ + SO32- H2O(l) + SO2(g)

2H+ + M M2+ + H2(g)

What are the products of the reaction of calcium carbonate with acetic acid? CaCO3 +

CH3COOH

1. (CH3COO)2Ca(aq) + H2CO3(aq)

2. (CH3COO)2Ca(aq) + H2O(l) + CO2(g)

3. (CH3COO)2CO3(aq) + H2Ca(aq)

4. (CH3COO)2Ca(s) + H2CO3(aq)

5. (CH3COO)2Ca(s) + H2O(l) + CO2(g)

Oxidation Reduction Reactions

REDOX REACTIONSELECTRON-TRANSFER REACTIONS

Oxidation and Reduction

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

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, O2

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.

What is the oxidation number of H in H2O?

1 2 3 4 5 6 7 8 9

1% 2%0%

14%

0%

5%7%

2%

69%1. +52. +43. +34. +25. +16. 07. -18. -29. -3

What is the oxidation number of O in H2O?

1 2 3 4 5 6 7 8 9

0% 0% 0% 0% 0%

89%

11%

0%0%

1. +52. +43. +34. +25. +16. 07. -18. -29. -3

What is the oxidation number of N in N2?

1 2 3 4 5 6 7 8 9

0%

5%

1%4%

1%4%4%

76%

5%

1. +52. +43. +34. +25. +16. 07. -18. -29. -3

What is the oxidation number of N in NO2?

1 2 3 4 5 6 7 8 9

1%

24%

1%

32%

4%

8%9%

5%

15%

1. +52. +43. +34. +25. +16. 07. -18. -29. -3

What is the oxidation number of N in NO3

-?

1 2 3 4 5 6 7 8 9

56%

5%

18%

4%

0%3%

5%3%

8%

1. +52. +43. +34. +25. +16. 07. -18. -29. -3

What is the oxidation number of O in OF2?

1 2 3 4 5 6 7 8 9

1% 1% 1%

43%

0%

24%

5%

8%

15%

1. +52. +43. +34. +25. +16. 07. -18. -29. -3