Nitric acid is a very powerful strong acid and it can react with ethanol without a catalyst. Let us predict the mechanism between the reaction of HNO3 and C2H5OH.
HNO3 or nitric acid is an inorganic mineral acid having a molar mass of 63.012 g/mol. Where C2H5OH or ethanol is an organic compound having -OH functionality. The reaction between them was produced to burn the carbon and formed the corresponding carbon-containing molecules. The basicity of the ethanol depends on the presence of an electronegative O atom.
Although there will be some parameters and limitations present in this reaction. Now we can discuss more the mechanism of the reaction like enthalpy, redox reaction, intermolecular force, conjugate pairs, etc with an explanation in the following part of the article.
1. What is the product of HNO3 and C2H5OH?
CO2 and NO2 along with some H2O molecules are formed as major products formed when HNO3 and C2H5OH are reacted together.
HNO3 + C2H5OH = CO2 + NO2 + H2O
2. What type of reaction is HNO3 + C2H5OH?
HNO3 + C2H5OH reaction is an example of an acid-base reaction, a double displacement reaction, and a redox and precipitation reaction. It is also a hydrolysis reaction as in the course of the reaction, water is formed.
3. How to balance HNO3 + C2H5OH?
HNO3 + C2H5OH = CO2 + NO2 + H2O, we have to balance the equation in the following way-
- First, we label all the reactants and products by A, B, C, D, and E as there are five different molecules obtained for this reaction and the reaction looks like this,
- A HNO3 + B C2H5OH = C NO2 + D CO2 + E H2O
- Equating the coefficients for the same type of elements by rearranging them.
- After the rearrangement of coefficients of the same elements by their stoichiometric proportion, we get,
- H = A = 6B = 2E, N = A = C, O = 3A = B = 2C = 2D = E, C = 2B = D.
- Using the Gaussian elimination and equating all the equations we get, A = 12, B = 1, C = 12, D = 2, and E = 9
- The overall balanced equation will be,
- 12 HNO3 + C2H5OH = 2 CO2 +12 NO2 + 9 H2O
4. HNO3 + C2H5OH titration
To estimate the quantity of nitrogen dioxide or strength of acid we can perform a titration between C2H5OH and HNO3.
Apparatus used
We need a burette, conical flask, burette holder, volumetric flask, and beakers for this titration.
Titre and titrant
HNO3 versus C2H5OH, HNO3 acts as a titrant taken in the burette and the molecule to be analyzed is C2H5OH taken in a conical flask.
Indicator
The whole titration is done in an acidic medium or acidic pH so the best suitable indicator will be phenolphthalein which gives perfect results for this titration at given pH.
Procedure
The burette is filled with standardized HNO3. C2H5OH is taken in a conical flask along with respective indicators. HNO3 is added dropwise to the conical flask and the flask is shaken constantly. After a certain time, when the endpoint arrives, the indicator changes its color and the reaction is done.
5. HNO3 + C2H5OH net ionic equation
The net ionic equation between HNO3 + C2H5OH is as follows,
H+(aq.) + NO3–(aq.) + C2H5OH (aq.) = CO2(g) + NO2(g) + H+(aq.) + OH–(aq.)
- HNO3 will be ionized as proton and nitrate as it is strong acid and electrolyte.
- After that C2H5OH dissociates very slowly almost zero dissociation as the dissociation constant for organic molecules is very low.
- In the product part, NO2 and CO2 exist in the gaseous state so they cannot be dissociated.
- H2O ionized into proton and hydroxide ion.
6. HNO3 + C2H5OH conjugate pairs
HNO3 + C2H5OH has the following conjugate pairs,
- Conjugate pair of HNO3 = NO3–
- Conjugate pair of OH– = H2O
- Conjugate pair of C2H5O– = C2H5OH
7. HNO3 + C2H5OH intermolecular forces
HNO3 + C2H5OH has the following intermmolecular forces,
- The intermolecular force present in HNO3 is the strong electrostatic force and coulumbic force between protons and nitrate ions.
- In C2H5OH there are H-bonding and covalent forces present.
- In NO2 van der waal’s force is present and for water H-bonding is present.Intermolecular Forces
8. HNO3 + C2H5OH reaction enthalpy
HNO3 + C2H5OH reaction enthalpy is +2841.32 KJ/mol which can be obtained by the formula: enthalpy of products – enthalpy of reactants. Here the change in enthalpy is positive.
| Molecule | Enthalpy (KJ/mol) |
|---|---|
| C2H5OH | -1366.8 |
| HNO3 | -206.28 |
| NO2 | +33.18 |
| CO2 | -393.5 |
| H2O | -68 |
9. Is HNO3 + C2H5OH a buffer solution?
In the reaction between HNO3 + C2H5OH, there is no such buffer formed but the mixture of CO2 and H2O formed carbonic acid which can control the pH even by adding a base.
10. Is HNO3 + C2H5OH a complete reaction?
The reaction between HNO3 + C2H5OH is complete because it gives two major gaseous products along with water as a by-product.
11. Is HNO3 + C2H5OH an exothermic or endothermic reaction?
The reaction of HNO3 + C2H5OH is endothermic in terms of thermodynamics first law. This reaction absorbed more heat as energy and temperature to the surroundings, where δH is always positive.
12. Is HNO3 + C2H5OH a redox reaction?
HNO3 + C2H5OH reaction is a redox reaction because in this reaction carbon gets oxidized and nitrogen gets reduced. Where HNO3 acts as an oxidizing agent and C2H5OH acts as a reducing agent.
13. Is HNO3 + C2H5OH a precipitation reaction?
The reaction between HNO3 + C2H5OH is a precipitation reaction because NO2 and CO2 get precipitated in the solution at certain pH.
14. Is HNO3 + C2H5OH reversible or irreversible reaction?
The reaction between HNO3 + C2H5OH is irreversible because it produced NO2 and CO2 gas. Due to the production of the gaseous molecule, the entropy of the reaction increases. Therefore, the equilibrium shifts towards the right-hand side only or forward directions.
HNO3 + C2H5OH —-???? NO2(g) ↑+ CO2(g) ↑+ H2O
15. Is HNO3 + C2H5OH displacement reaction?
The reaction between HNO3 + C2H5OH is an example of a double displacement reaction. Because in the reaction, H+ is displaced by ethanol and C is also displaced by HNO3.
Conclusion
The reaction between HNO3 and C2H5OH is an endothermic process so it does not required any type of catalyst for proceed the reaction. The transition state of the energy profile diagram for the reaction is very low. It is an industrially important reaction for the production of NO2 gas.
Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.
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