January 2019 Ny Regents Chemistry Exam
47 What are the two oxidation states of nitrogen in NH4NO2?
(1) +3 and +5
(2) +3 and -5 (3) -3 and +3
(4) -3 and -3
Solution: To find oxidation states, let's first look at some rules for oxidation numbers.
Oxygen is usually -2 unless in peroxides
Hydrogen is +1 unless it is bonded to a metal
The sum of oxidation numbers in a polyatomic ions is equal to the charge of the polyatomic ion.
The compound present is composed of two polyatomic ions: NH4+ and NO2-
NH4+
x+(+1*4)=+1
x= -3
NO2-
x+(-2*2)=-1
x=+3
Answer: 3
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