Oxidation Question from Destroyer

[dental13]

This one is 2008 version of Destroyer
GChem Q# 36
Calculate the oxidation number on N and P in KNO2 and PO4(-3) respectively

The answer is +3, +5

Anyone can break this down for me? I am really confused here

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[gigawatt]

This one is 2008 version of Destroyer
GChem Q# 36
Calculate the oxidation number on N and P in KNO2 and PO4(-3) respectively

The answer is +3, +5

Anyone can break this down for me? I am really confused here

KNO2 is a neutral molecule, so total charge is 0:
0 = K + N + 2(O) = 1 + N + 2(-2)
N = 3

Likewise, for phosphate:
-3 = P + 4(O) = P + 4(-2)
P = 5

You know Group 1 = +1 and Group 2 = +2 based on their position in the periodic table. Halogens are -1. Oxygen is -2. Hydrogen can be +1 or -1 depending on if it's an acid or hydride. After that, just plug and chug.

 

[rpatel8]

Its just asking for the oxidation numbers for N and P separately. For KNO2, K is +1 and O2 is -2......so 2(-2)= -4. 0= -4+1+ 3 to get to 0 charge so the oxidation number of N is +3.

For PO4(3-) O is -2 so -2(4)= -8. -3= -8 + 5 so the oxidation of P is +5.

 

[Ibraiz]

To find the oxidation number of an element, start with assigning group 1 or 2 elements their respective oxidation number.

KNO2 -->
K = +1
O2 = -4 ( -2 for each Oxygen atom)
You have to know the overall charge of the NO2 ion which is -1. So -4 from O2 and X from N must add up to -1. Do the math -4 + X = -1 you get +3

(PO4)-3

how about you try doing this by yourself as a practice and ask if you can't figure it out.

 

[dental13]

To find the oxidation number of an element, start with assigning group 1 or 2 elements their respective oxidation number.

KNO2 -->
K = +1
O2 = -4 ( -2 for each Oxygen atom)
You have to know the overall charge of the NO2 ion which is -1. So -4 from O2 and X from N must add up to -1. Do the math -4 + X = -1 you get +3

(PO4)-3

how about you try doing this by yourself as a practice and ask if you can't figure it out.

I figured the question in wrong way. I thought it was talking about formal charge instead of oxidation number