Oxidation number

[Resin]

I have a difficult time determining the oxidation number. Is there an easy way to find this?

1. In which of the following does iodine have an oxidation # of 3

a. I2
b. IF7
c. IO3^-
d. IBr
e. IO2^-

the answer is E. I know the oxidation # of a is 0. How do you determine the other ones?

2. In which two compounds does nitrogen have the same oxidation number?

a. N2O3 and HNO3
b. N2O5 and HNO3
c. NO2 and N2O3
d. N2O4 and HNO2
e. HNO2 and NH3

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[Gordon9721]

#2 is B
n2o5 nitrogen's # is +5 and hno3 it is +5 since o is always -2 and h is +1

 

[erichen]

I have a difficult time determining the oxidation number. Is there an easy way to find this?

1. In which of the following does iodine have an oxidation # of 3

a. I2
b. IF7
c. IO3^-
d. IBr
e. IO2^-

the answer is E. I know the oxidation # of a is 0. How do you determine the other ones?



a. I2 = 0 naturally occurring diatomic molecule.

b. IF7 = 7+ because u look at the F7 which is 7-. in this case, u can look at the iodine as a cation, despite its usual charge. this is how u find oxidation numbers for covalenltly bonded nonmetal+nonmental molecules.

c. IO3^-= 5+, because although O3 has 6-, the overall charge is 1-, therefore the iodine is missing one electron, yielding 5+. if you take 5+ and add it to 6-, the overall is 1-, which is what is igiven.

d. IBr= 1+, because Br is 1-.

e. IO2^- = 3+, because although O2 yields 4-, the iodine has to make the overall chage 1-. this is only possible if iodine is 3+, since 3+ and 4- makes 1-.

 

[platinumcaps]

Q1 ----> e because oxygen usually has an oxidation # of -2. so two oxygens would be -4, and since the total charge on the molecule is -1, then iodine must be +3.

 

[platinumcaps]

Q2 -----> B because oxygen has an oxidation # of -2 so five of them would make a -10 charge. Since N2O5 is overall neutral, the two nitrogens must balance out the -10 charge. Thus each nitrogen is +5.
The oxygen in HNO3 has a -2 oxidation # so three oxygens would equal a -6 charge. Hydrogen has a +1 charge here. -6 and +1 makes -5 charge. Again, there is an overall neutral charge on the entire molecule so -5 must be balanced out by the leftover nitrogen atom. The atom is therefore +5 charge.

 

[Resin]

Thanks everyone for the clarification.

I noticed that I did not take the net charge into consideration. That completely threw me off!