Home > Community > Why the oxidation state of nitrogen is -3 when dilute nitric acid reacts with zinc?
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Miriam Rios

Why the oxidation state of nitrogen is -3 when dilute nitric acid reacts with zinc?

Basecrete Global??  Follow

Reaction of zinc with concentrate HNO3 give zn(NO3) 2+ NO2gas+H2o

And with dilute give zn(nO3) 2+N20gas+H2o

Thanks for reading please upvote and follow

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Olivia (Gloria)  Follow

Look at the structure of HNO3

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Brittany Roma  Follow

In Nitric Acid, HNO3, we have NO3^- ion in which nitrogen has the oxidation state N(V) not -3. Nitrogen can have a variety of oxidation states: in NH3, N(-3); NO, N(II); HNO3, N(V); N2O, N(I); NO2, N(IV), etc…

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Andras Ivan  Follow

Nitric acid has oxidizing property as well as acidic property. Hydrogen, produced by the reaction between Zn and HNO3, is instantaneously oxidized to water. So, hydrogen gas is not obtained. There are four reactions depending on the conditions.

1) Hot and Conc HNO3:

Zn + 4HNO3 → Zn(NO3)2 + 2NO2 + 2H2O

2) Cold and 1:1 HNO3:

3Zn + 8HNO3 →3Zn(NO3)2 + 2NO + 4H2O

3) Cold and dil HNO3:

4Zn + 10HNO3 →4Zn(NO3)2 + N2O + 5H2O

4) Cold and very dil HNO3:

4Zn + 10HNO3 → 4Zn(NO3)2 + NH4NO3 + 3H2O

Hope this helps.

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Callum Russell  Follow

Suppose "-3" means "decreases by 3".

The reaction of dilute nitric acid with zinc is redox. Zinc is oxidized to zinc ion, while dilute nitric acid is reduced to nitrogen monoxide gas. The equation is
3Zn(s) + 2NO₃⁻(aq) + 8H⁺(aq) → 3Zn²⁺(aq) + 4H₂O(ℓ) + 2NO(g)

The oxidation state of N in HNO₃ is +5, while the oxidation of N in NO in +2. In the reaction,
the oxidation state of N decreases by 3.
Change of oxidation state of N = -3

Remarks:
• When concentrated nitric acid reacts with zinc, nitrogen dioxide gas is evolved.
• When dilute to moderately concentrated nitric acid reacts with zinc, nitrogen monoxide gas is evolved.
• When very dilute nitric acid reacts with zinc, hydrogen gas is evolved.

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Andy Heilveil  Follow

When metals( Cu, Na, Zn) react with mineral acids like dil HCL and H2SO4, hydrogen gas is evolved.

Nitric acid is an acid that decomposes very quickly.

When metals react with mineral acids except nitric acid, the respective salt and H2 gas is evolved.

How do you confirm that the gas released is hydrogen?

When you introduce a burning splinter the gas will burn with a pop sound.

That’s all!!!!

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