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Dinitrogen Pentoxide

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Last updated date: 25th Feb 2024
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What is Dinitrogen Pentoxide?

Dinitrogen pentoxide is a chemical compound containing only nitrogen and oxygen. As the name suggests, a single molecule of Dinitrogen Pentoxide will have 2 (di) nitrogen atoms and 5 (Pent) oxygen atoms. The chemical formula of the compound is N2O5

 

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Dinitrogen pentoxide is the anhydride form of nitric acid that can exist as a colourless crystal. It melts at 30°C. A rather unstable oxide of nitrogen, dinitrogen pentoxide is used as an oxidiser in a number of chemical reactions. It is a nitrating agent. Nowadays, however, it is being replaced largely by nitronium tetrafluoroborate. 

Chemical Structure: Lewis Structure of Dinitrogen Pentoxide (N2O5)

As mentioned above, Dinitrogen Pentoxide is composed of 2 Nitrogen atoms and 5 Oxygen atoms. Now, if you want to draw the Lewis Dot Structure of N2O5, you first have to know a few basic things:

  • Nitrogen has 5 valence electrons

  • Oxygen has 6 valence electrons

So, in N2O5, there will be: 

  • 5*2 = 10 valence electrons of Nitrogen

  • 6*5 = 30 valence electrons of Oxygen

Hence, we will be working with 40 valence electrons.

 

Now carefully go through the following facts:

  • The total number of atoms in N2O5 is 2+5 = 7

  • We know that each of these atoms must have 8 electrons in its valence shell. So there should be 7 * 8 = 56 valence electrons in the compound.

  • So we have 40 electrons at hand. Deficit is 56 - 40 = 16 electrons. Since the compound has 2 atoms only - there will be a total of \[\frac {16}{2}\] = 8 bonds. 

So, now let us first arrange the atoms in the compound.

 

So the double bond completes the 8 bonds. You might ask - why can’t the two nitrogen atoms form double bonds with the oxygen in the middle? That would ultimately make the oxygen electropositive which is unnatural - Oxygen should be kept electro-negative as this is what we see in nature.

 

Now let us complete the octet and see what the Lewis dot diagram of N2O5 looks like:

 

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So the octet rule is fulfilled. The nitrogen atoms have a positive charge of +1 each. The charge of oxygen atoms is 0.

 

Key Takeaways

  • N2O5 is named Dinitrogen Pentoxide because it has 2 Nitrogen atoms and 5 Oxygen atoms.

  • The total number of valence electrons if we take into account each of the atoms in N2O5 is 40 - 10 of two nitrogens and 30 of 5 Oxygens

  • While drawing the Lewis Dot structure of N2O5, you must remember the fact that Oxygen is electronegative.

 

Properties of Dinitrogen Pentoxide 

The important properties of dinitrogen pentoxide are as follows:

  • It is a colourless crystalline solid. However, you cannot keep it under room temperature (at least in India) because its melting point is 30°C.

  • Upon being melted at 30°C, it transforms into a yellowish liquid.

  • Be careful while handling N2O5. If you heat it beyond 30°C, it will get decomposed but the decomposition will take place along with the explosion. Upon heating, N₂O₅ will get dissociated into nitrogen dioxide (NO2) and oxygen (O2).

N2O5 is an Acidic Anhydride 

Anhydride is a compound that is formed after removing water molecules from a bigger compound. So anhydride basically means - without water. 

 

N2O5 is just HNO3 without water. Since HNO3 or Nitric acid is an acid, dinitrogen pentoxide is acid too. If HNO3 can be dehydrated to obtain N2O, we should be able to do the reverse as well. Here goes the reaction:

 

N2O5 + H2O → 2HNO3

 

So we can get nitric acid by adding water to dinitrogen pentoxide.

Preparation of N2O5 

We can prepare dinitrogen pentoxide (N2O5) by dehydrating nitric acid with Phosphorus pentoxide. The reaction will look like this:

 

P4O10 + 12HNO3 → 4H3PO4 + 6N2O5

 

Furthermore, since N2O5 is formed from HNO3, the salt that N2O5 forms will also be the salt of HNO3. The reaction will look like this:

 

N2O5 + NaOH → NaNO3 + H2O

 

We get sodium nitrate which is a salt of HNO3.

 

The ionic form of N2O5:

 

The ionic form of Dinitrogen pentoxide is nitronium nitrate. This can be demonstrated with the help of the following reaction:

 

N2O5 + NaCl → NaNO3 + NO2Cl

 

The sodium atom has a +1 charge while the NO3 atom has a -1 charge. Hence the ionic form of N2O5 is NaNO3. However, you must also note that in NO3 the Oxygen and Nitrogen have covalent bonds and we know that covalent bonds do not have ions. Interesting, isn’t it?

Key Takeaways

  • Dinitrogen Pentoxide is colourless. Up to 30°C, it remains solid. Then it starts melting. At 40°C, it explodes and decomposes into NO₂ and O₂.

  • It is a dehydrated form of nitric acid.

  • If added water, it can again turn into nitric acid.

  • Since it contains no water, it is known as anhydride.

 

Decomposition of Dinitrogen Pentoxide 

When you are asked to find the rate of the decomposition of N₂O₅, the passage of time will be given, the initial concentration of the compound and the final concentration of the compound after the given time has elapsed will be given.  

 

The balanced formula looks like this:

 

2N2O5 → 4NO2 + O2

 

So suppose the passage of time is x. The initial concentration was y and the ultimate concentration is z, then the formula to know the average rate of decomposition will be:

 

-½(y−Z)molL⁻¹/x 

 

The actual formula looks like this: 

 

Rate of decomposition =  \[\frac {1}{2} \frac {-\Delta N_2O_5}{\Delta T} \]

 

Why \[\frac {1}{2}\]? Because we have written 2NO2. Why a minus sign? Because the concentration is getting depleted.

 

If we are asked to find the rate of formation of NO2, the formula would be:

 

 \[\frac {1}{4} {\frac {\Delta NO_2}{\Delta T}} \]

 

You will think why are we writing \[\frac {1}{4}\]? It is because we have written 4 NO2. Why + \[\frac {1}{4}\] and not \[-\frac {1}{4}\]? It is because we are gaining NO2

Uses of Dinitrogen Pentoxide 

Dinitrogen pentoxide was used as a nitrating agent. However, due to its unstable nature, these days Nitronium Tetrafluoroborate is being used instead of N2O5. A potential evil use of N2O5 is making TNT from it.

 

Nitrogen is one of the most important elements in the universe. We need to learn about it because our lives and our Earth can be affected by it. So, we need to learn about all the compounds related to Nitrogen and that includes Dinitrogen Pentoxide. 

Did You Know? 

N2O5 is indirectly responsible for Ozone layer depletion. 

Conclusion

Chemistry is incomplete without the study of the compounds of Nitrogen. The article discusses very important information that is always asked in examinations and is also important for knowing the compounds of nitrogen. Students can refer to this article on dinitrogen pentoxide for learning about the compound.

FAQs on Dinitrogen Pentoxide

1. Is dinitrogen pentoxide Ionic or covalent?

N2O5 is made up of two nonmetals - Oxygen and Nitrogen. The ionic charge of Oxygen is -2 and the ionic charge of Nitrogen is -3. When two nonmetals or two negatively charged atoms try to form bonds, they always form covalent bonds. Hence, Dinitrogen Pentoxide is not ionic — it is covalent. Dinitrogen Pentoxide is acidic. It is formed by dehydrating nitric acid. Hence, if we add water we can get back HNO3. So Dinitrogen Pentoxide is acidic. Dinitrogen Pentoxide is made up of atoms of just two elements - Nitrogen and Oxygen. Hence N2O5 is a binary compound. 

2. Is Dinitrogen Pentoxide Acidic or Basic?

Dinitrogen Pentoxide is acidic. It is formed by dehydrating nitric acid. Hence, if we add water we can get back HNO3. So Dinitrogen Pentoxide is acidic.

2. How is dinitrogen pentoxide formed?

The chemical formula of Dinitrogen Pentoxide is N2O5. N2O5 can be prepared by dehydrating nitric acid with Phosphorus pentoxide. Dinitrogen Pentoxide is mainly used as a nitrating agent. It can also be used to make explosives. However, people don’t use N2O5 much today. The reaction will look like this:


P4O10 + 12HNO3 → 4H3PO4 + 6N2O5

4. What is dinitrogen pentoxide decomposition?

Dinitrogen Pentoxide is a colourless, crystalline solid. When heated, it transforms into NO2. Decomposition of N2O5 means that, if heated at 40-degree celsius and more, Dinitrogen Pentoxide will decrease in composition and it will turn into NO2 and O2. It looks like this:


2N2O5 → 4NO2 + O2


If you add water to Dinitrogen pentoxide, it will turn into nitric acid. This is what proves that Dinitrogen Pentoxide is acidic.

5. What is the Chemical Formula of Dinitrogen Pentoxide ?

The chemical formula of Dinitrogen Pentoxide is N2O5.

6. Does Dinitrogen Pentoxide React with Water?

Yes, if you add water to Dinitrogen pentoxide, it will turn into nitric acid. This is what proves that Dinitrogen Pentoxide is acidic.

7. Is Dinitrogen Pentoxide Gas?

No, Dinitrogen Pentoxide is a colourless, crystalline solid. When heated, it transforms into NO2.

8. Is Dinitrogen Pentoxide Binary?

Yes, Dinitrogen Pentoxide is made up of atoms of just two elements - Nitrogen and Oxygen. Hence N2O5 is a binary compound. 

9. What is Dinitrogen Pentoxide Used for?

Dinitrogen Pentoxide is mainly used as a nitrating agent. It can also be used to make explosives. However, people don’t use N2O5 much today.