Oxidation-Reduction Worksheet



Oxidation-Reduction Study Guide Chemistry

Answer questions on this sheet, use your notes and the text to help you.

I. Oxidation Numbers…

1. In chemical reactions, elements on the left side of the periodic table tend to ____________

electrons and those on the right side tend to ______________ electrons.

2. Define oxidation number._______________________________________________________

___________________________________________________________________________

3. a. What is the oxidation number for a pure element? ______

b. What is the oxidation number for oxygen in all compounds except peroxides and metal hydrides? _____

4. What does the algebraic sum of the oxidation #’s for all atoms equal in

a. Neutral compound _______________ b. Polyatomic ion __________________

5. Assign oxidation #’s to each atom in the following: Ex. CO2…would be C+4 O2-2

a. H2O b. NO2 c. KMnO4 d. SO4

6. Give the oxidation #’s of nitrogen in each of the following compounds.

a. NO2 b. N2O5 c. N2O d. NO e. HNO3 f Ca3N2

II. Redox reactions…

The Facts:

OXIDATION REDUCTION

• Loss of electrons - gain of electrons

• Increase in oxidation - decrease in oxidation #

• Substance oxidized is the reducing agent - substance reduced is the oxidizing agent

• e- is written on product side in half reaction - e- is written on the reactant side in half reaction….Ex. Na ( Na+ + e- reaction. Ex. Cl + e- ( Cl-

REDOX REACTION: any chemical process in which elements undergo a change in oxidation #.

Remember!

L E O THE LION SAYS G E R

O L X A L E

S E I I E D

E C D N C U

T A T C ( Memorize this, it will help!

R T R T

O I O I

N O N O

S N S N

1. Define: the following terms

a. oxidation ____________________________________________________________________

b. reduction ____________________________________________________________________

c. oxidizing agent ________________________________________________________________

d. reducing agent ________________________________________________________________

2. Are the following half reactions oxidation (ox.) or reduction (red)?

a. Cu+2 + 2e-2 ( Cu0 ___________________________________

b. Fe0 ( Fe+3 + 3e- ___________________________________

c. Mn+2 ( Mn+4 + 2e- ___________________________________

d. Mn+7 + 5e- ( Mn=2 ___________________________________

3. In the following reactions, label what is oxidized and what is reduced. (Hint: first assign oxidation numbers to each element in reactants and products.)

a. 4Fe + 3O2 ( 2Fe2O3 ox.____________ red..___________

b. 3CuSO4 + 2Al ( Al2(SO4)3 + 3Cu ox ___________ red ___________

c. H2S + 2HNO3 ( H2SO4 + 2NO2 + H2O ox ____________ red_____________

III. BALANCING REDOX REACTIONS pp. 645-653

THE FACTS:

Mass, atoms and charge must be conserved.

Mass…must have the same # and type of atoms on both sides of the equation.

Charge..e- lost = e- gained

____Fe3+ + ___Sn2+ -> ___Fe2+ + ____Sn4+

____ Fe + ____ Cu2+ -> _____Fe2+ +______Cu

IV. Electrochemistry

Oxidation takes place at the anode (an ox)

• Reduction takes place at the cathode (red cat)

Electrochemical Cells

• Electrochemical Cells produce electrical current from chemicals.

• Batteries are examples of Electrochemical Cells.

• Electrochemical Cells are spontaneous…

• Oxidation takes place at the anode (an ox)

• Reduction takes place at the cathode (red cat)

• Anode is negative

• Cathode is positive

• Electron’s (Current) flow from anode to cathode.

Electrolytic Cells

• Electrolytic cells use electrical current to do work.

• Electrolysis and electroplating are examples of electrolytic Cells.

• Electrochemical Cells are nonspontaneous… Oxidation takes place at the anode (an ox)

• Reduction takes place at the cathode (redcat)

• Anode is positive

• Cathode is negative

• Current flows from anode to cathode.

Electrochemical/Galvanic Cell

[pic]

1. What is an electrochemical cell? Give an example.

2. Batteries are examples of ___________________________________ cells.

3. Electrochemical cells are examples of _________________________ (spontaneous, nonspontaneous) change.

4. A set of electrodes and electrolytes in which a spontaneous redox reaction is used to produce electrical energy is

called a _________________ cell.

5. Oxidation takes place at the ___________________________.

6. Reduction takes place at the __________________________.

7. In an electrochemical cell, the anode has a ______________ charge and the cathode has a ___________ charge.

8. Batteries are _______________ cells.

9. List three types of batteries. ______________ and _____________ and ____________ .

10. What is an electrolytic cell? Give an example.

11. Discuss the electrolysis of water. Include the equation for the reaction.

12. Discuss the process of electroplating.

13. Electrolytic cells are examples of _________________________ (spontaneous, nonspontaneous) change.

14. List two electrolytic processes. _______________________ and ___________________________

15. In an electrolytic cell, the anode has a ______________ charge and the cathode has a ___________ charge.

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