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# Explanation of oxidation number and reduction

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1) What is the oxidation number of nitrogen in N2O4 (dinitrogen tetraoxide?

First, it has no charge; therefore N2 + 4(-2) = 0
N2 = 8, and thus N = +4. Is this right or wrong? Someone told me N = +2?

2) Nickel(II) nitrate is reduced to nickel metal in an oxidation-reduction reaction. Which is true?

a Nickel ion gains 2 electrons.
b Nickel ion loses 2 electrons.
c Nickel ion gains 1 electrons.
d Nickel ion loses 1 electrons.
e Nickel metal gain 2 electrons.
f Nickel metal loses 2 electrons.

Now I solved this by saying Ni(NO-)2. then set = to 0. and went from their, but got wrong answer. I got N=5, Ni=+1, Ni=+2, O=-6. My answer was C, but wrong.
Using the set everything = to a 0 charge and figure out each number for each element show me step by step how to set this up and get the right answer. Also, what is the difference between a nickel ion and nickel metal?

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## SOLUTION This solution is FREE courtesy of BrainMass!

To 1): You have calculated correctly. The oxidation number of N = +4

To 2.)

As the formula Nickel(II) nitrate indicates Nickel is an ion with the charge +2.
Roman letters in brackets show the number of electrons the metal has lost / given to another atom.
These electrons are transferred to other atoms during the chemical reaction which is forming the metal ion.

The word "metal" indicates that its oxidation number is 0. Metals as elements are not in an ionic state and so they don't have a positive or negative charge. 'Nickel ion' means that the nickel atom has lost electrons and therefore has become a positive charged nickel ion.
So, when we say ' Ni 2+ ' is reduced to nickel metal it means that it gains 2 electrons back ( Answer A ).

If the question is limited on the metal ion we don't need to calculate the oxidation numbers of every atom in the given molecule. We only have to look on the change of the metals charge / oxidation number.

You also can get the number of electrons if you consider the charge of the (NO3)- ion. Its (-1) and we have 2 molecules in Nickel(II)nitrate, so Nickel must have (+2) so that the complete molecule has the charge 0.

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This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

© BrainMass Inc. brainmass.com September 28, 2022, 3:18 am ad1c9bdddf>
https://brainmass.com/chemistry/oxidation-reduction-and-electrochemistry/explanation-oxidation-number-reduction-36363