Exam 2 Chapter 3 And 4

Question 1

Oxidation state rule #1 to find the oxidation state in a neutral compound

Answer 1

In a neutral compound all oxidation numbers add to zero 0.
Make an equation that adds to 0

Question 2

Oxidation state rule #2 to find the oxidation state in an ION….?
Hint SO4²-

Answer 2

In an ION the sum of oxidation numbers add to the ion charge Ex.
SO4²- the ion is a -2 so
(O)xygen is -2 X 4 = -8
(S)ulfur must be +6
Because +6 + 4(-2) = -2 which is the charge of the ion

Question 3

Free elements or monatomic substances where there is only one type of atom in the substance have an oxidation number of … ?
Rule #3

Answer 3

Zero
Ex. Na, Fe, H2, O2, S8 all oxidation numbers are 0

Question 4

What is the oxidation number of Fluorine F?
Rule #4
Has precedence over oxygen being -2
Hint like the alphabet

Answer 4

-1
Always beats (comes before) the “oxygen has a -2 oxidation number” rule
Ex.
In OF2
Oxygen has a +2 charge because
Fluorine has a -1 charge and the compound
Must be neutral or have a 0 net charge

+2 + 2(-1) = 0

Question 5

What is the oxidation number of F2?
Hint - Rule 3

Answer 5

Although F is always has an oxidation number of -1
It is a free element and is made of one type of atom so it is
0
Rule #3

Question 6

Rule #5 What is the oxidation number of group 1 , group 2 and group 3 metals?

Answer 6

Always
Group 1 = +1
Group 2 = +2
Group 3 Al and Ga = +3
UNLESS RULES 1-4 APPLY
WHICH TAKE PRECEDENCE OVER THIS RULE

Question 7

RULE #6 What is the oxidation number for hydrogen with nonmetals and hydrogen with metals or boron?

Answer 7

H with metals = +1
H with non-metals AND Boron = -1
UNLESS rules 1-5 apply

Question 8

RULE #7 What is the oxidation numbers of oxygen?
And what are the 2 EXCEPTIONS

Answer 8

Oxygen is always -2
Except
when bonded to Flourine
When in peroxide H2O2 or Na2O2

Question 9

RULE #8 LAST RULE what are the oxidation numbers for
Group 17(7A) =
Group 16(6A) =
Group 15(5A) =

Answer 9

If none of the other rules apply
Group 17(7A) = -1
Group 16(6A) = -2
Group 15(5A) = -3

Question 10

Is K+ + Cl- —> KCl. A Redox reaction?
If not make it a redox reaction

Answer 10

NO
Because there is no transfer of electrons The equation starts with ions. The ions were not made as a result of the reaction

K + Cl —> KCl
Both K and Cl are neutral and became ions during the reaction.

Question 11

Name CuCl
CuCl2
And why

Answer 11

Copper (1) Chloride
Copper (2) Chloride
The chloride and copper one has an assumed -1 ion charge, which would make the copper a +1 ion
The chloride and copper two chloride has a two subscript, making it -2, so the copper would be the +2 ion