Oxidation and Reduction Test

Write the half-reaction equation for lead (II) being oxidized to lead (IV).

Pb²⁺ → Pb⁴⁺ + 2e⁻

In the reaction Al° +Cr +3 yields Al+3+ Cro the reducing agent is (1 point)

• AlO

A redox reaction ALWAYS involves (1 point)

•   a change in oxidation number

Which half-reaction correctly represents reduction?/

  Mn7+ + 3е- → Mn4+

3. In the reaction AlO +Cr +3 yields Al+3+ CrO the reducing agent is

• Al0

The algebraic sum of the oxidation numbers of the atoms in a COMPOUND (1 point)

•   is always zero

2. Which is a redox reaction? (1 point)

• 2 H2O-> 2H2 + O2

3. Given the reaction: 2 Na + 2H20 -> 2 Na+ + 2 OH - + H2 Which substance HAS BEEN oxidized? (1 point)

•   Na

4. . (1 point)

When the redox equation -

C-3+(aq) + 3Mn(s) →

Mn2+(aq) + _

Crs) is completely balanced,

the coefficient of Cr3+ (aq) will be

• 2

1. What are the oxidation numbers in the ion SO32?

• S= +4, 0=-2

2. In a redox reaction, CO is CHANGED TO CO2. How many electrons must be lost or gained by C?

• two lost

If the element "X" forms the oxides XO and X203, the oxidation numbers of the element X are

(1 point)

• +2 and +3

1. In which substance is the oxidation number of nitrogen zero (1 point)

•   N2

2. What are the oxidation numbers in the compound H2 02? (1 point)

• H=+1, O=-1

3. What is the most common oxidation number of combined oxygen? (1 point)

• -2

4. Balance the following redox reaction using the half-reaction method. Sn + Ag+1 - Sn+2 +Ag

Sn + Ag+ —> Sn2+ + Ag

If species change their oxidation numbers, the process is an) (1 point)

•   oxidation-reduction reaction

3. What are the oxidation numbers in the compound NO2? (1 point)

• N=+4, 0=-2

4. Oxygen has a positive oxidation number in the compound (1 point)

• OF2

Extra Credit: Make sure to Balance MASS AND CHARGE (1 point)

Which redox equation is correctly balanced? //

•   Br2 + Hg → Hg2+ + 2Br-

In a redox reaction, MnO4- is changed to MnO4 -2. How many electrons must be lost or gained by Mn? (1 point)

•   one electron gained

2. Balance the following redox reaction using the half-reaction method. Sn + Agt1-> Snt2 +Ag.

Sn + Ag —> Sn2+ Ag

4. Another name for an oxidation-reduction reaction is a(n) (1 point)

•   redox reaction

1. Which change occurs when an Sn+2 ion is oxidized?

•   Two electrons are lost

3. As an 5-2 ion is oxidized to an 5° atom, the number of protons in its nucleus

•   remains the same

4. Write the half-reaction equation for silver(I) being reduced to a silver atom.

Ag+ + e- —> Ag

3. In a redox reaction, MnO4 is changed to Mn+2. How many electrons must be lost or gained by

Mn? (1 point)

•   five gained

What is the oxidation number of a monoatomic ion?

= to charge

3. In the reaction magnesium and oxygen yields magnesium oxide, which element is being reduced?

OXEGEN

4. The redox equation H2 + 02 -> 2 Ht + 0-2 is

•   correctly balanced for number of ATOMS but NOT for CHARGE.

The redox equation MnO- 4 + 4CO2 +  H+ -> 4CO+3 +Mn2+ + 4 H20 is (1 point)

•   correctly balanced.

2. In the compound Na2HPO4, which element has a negative oxidation number? (1 point)

• O

3. Redox equation 4 H+ +N2 -> NH4+ + N is (1 point)

•   correctly balanced for number of ATOMS but NOT for CHARGE.

4. What is the oxidation numbers in the compound H3O4? (1 point)

•   H=+1, P=+5, O=-2

What is the oxidation number of carbon in NaHCO

• +4