The Chemistry Behind HNO3 + Ag2O: 15 Facts You Should Know

Silver oxide is a basic metal oxide so it can easily react with strong acids like HNO₃. Let us see the mechanism behind the reaction of HNO₃ and Ag₂O.

Ag₂O or silver oxide is soluble in water and alkali as it can form H-bonding with the respective solvent. Here Ag is present in a +1 oxidation state which is a d¹⁰ configuration so the molecule has no extra crystal filed stabilization energy and adopted linear geometry. Nitric acid is a strong mineral inorganic acid.

The reaction between Ag₂O and HNO₃ does not require any catalyst and temperature or pressure. Let us discuss the mechanism of the reaction between nitric acid and silver oxide, the reaction enthalpy, the type of reaction, product formation, etc. in the following part of the article.

1. What is the product of HNO₃ and Ag₂O?

Silver nitrate is formed as a major product along with water as a by-product when HNO₃ and Ag₂O are reacted together.

HNO₃ + Ag₂O = AgNO₃ + H₂O

2. What type of reaction is HNO₃ + Ag₂O?

HNO₃ + Ag₂O reaction is an example of a salt formation reaction, single displacement reaction, and redox and precipitation reaction. Here, electrolytic salt is formed in the course of the reaction.

3. How to balance HNO₃ + Ag₂O?

HNO₃ + Ag₂O = AgNO₃ + H₂O this reaction is not balanced yet, we have to balance the equation in the following way-

• First, we label all the reactants and products by A, B, C, and D as there are four different molecules obtained for this reaction and the reaction looks like this,
• A HNO₃ + B Ag₂O = C AgNO₃ + D 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 = 2B, N = A = C, O = 3A = 2B = 3C =D, Ag = 2B =C
• Using the Gaussian elimination and equating all the equations we get, A = 2, B = 1, C = 2, and D =1,
• The overall balanced equation will be,
• 2 HNO₃ + Ag₂O = 2 AgNO₃ + H₂O

4. HNO₃ + Ag₂O titration

To estimate the quantity of nitrate or strength of acid we can perform a titration between Ag₂O and HNO_3.

Apparatus used

We need a burette, conical flask, burette holder, volumetric flask, and beakers for this titration.

Titre and titrant

HNO₃ versus Ag₂O, HNO₃ acts as a titrant taken in the burette and the molecule to be analyzed is Ag₂O 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. Ag₂O 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+ Ag₂O net ionic equation

The net ionic equation between HNO₃ + Ag₂O is as follows,

H⁺(aq.) + NO₃^–(aq.) + Ag₂O(s) = Ag⁺(aq.) + NO₃^–(aq.) + H⁺(l) + OH^–(l)

• HNO₃ will be ionized into H⁺ and nitrate as a counter ion as it is a strong electrolyte.
• Ag₂O remains undissociated because it exists in solid form and cannot be ionized.
• In the product part AgNO₃ ionized into Ag⁺ and NO₃^–as it is a strong electrolyte.
• Water ionized into proton and hydroxide ion in a liquid state.

6. HNO₃+ Ag₂O conjugate pairs

In the reaction, HNO₃ + Ag₂O conjugate pairs will be the corresponding de-protonated and protonated form of that particular species which are listed below-

• Conjugate pair of HNO3 = NO₃^–
• Conjugate pair of OH^– = H₂O

7. HNO₃ and Ag₂O intermolecular forces

HNO₃ + Ag₂O has the following intermolecular forces,

• The intermolecular force present in HNO₃ is the strong electrostatic force between protons and nitrate ions.
• In Ag₂O there are electronic interactions and coulumbic force present along with the metallic bond. It is also an electrostatic and ionic force present in AgNO₃, also van der waal’s attraction.

Molecule	Acting force
HNO3	Electrostatic, van der waal’s Dipole interaction, Covalent
Ag2O	Metallic bond, ionic interaction, Coulumbic force
AgNO3	Electrostatic force, ionic interaction
H2O	H-bonding, covalent force, ionic interaction

8. HNO3 + Ag₂O reaction enthalpy

HNO₃ + Ag₂O reaction enthalpy is -44.81 KJ/mol which can be obtained by the formula: enthalpy of products – enthalpy of reactants. Here the change in enthalpy is negative.

Molecule	Enthalpy (KJ/mol)
Ag2O	-31.05
HNO3	-207.36
AgNO3	-124.39
H2O	-241.8

9. Is HNO₃ + Ag₂O a buffer solution?

The reaction between HNO₃ + Ag₂O gives a buffer solution of AgNO₃ and H₂O which can control the pH of the reaction.

10. Is HNO₃ + Ag₂O a complete reaction?

The reaction between HNO₃ + Ag₂O is complete because it gives two major ones: a strong electrolyte and other is a water molecule.

11. Is HNO₃ + Ag₂O an exothermic or endothermic reaction?

The reaction of HNO₃ + Ag₂O is exothermic in terms of thermodynamics first law. This reaction released more energy and temperature to the surroundings, where δH is always negative.

12. Is HNO₃ + Ag₂O a redox reaction?

HNO₃ + Ag₂O reaction is a redox reaction because in this reaction N gets oxidized and oxygen gets reduced. Here HNO₃ acts as a reducing agent whereas Ag₂O acts as an oxidizing agent.

13. Is HNO₃ + Ag₂O a precipitation reaction

The reaction between HNO₃ + Ag₂O is a precipitation reaction because AgNO₃ gets precipitated in the solution at certain pH which can be removed by heating the solution.

14. Is HNO₃ + Ag₂O reversible or irreversible reaction?

The reaction between HNO₃ + Ag₂O is irreversible because it produced water and salt. The equilibrium shifts towards the right-hand side only or forward directions.

HNO₃ + Ag₂O —-> AgNO₃ + H₂O

15. Is HNO₃ + Ag₂O displacement reaction?

The reaction between HNO₃ + Ag₂O is an example of a single displacement reaction. Because in the above reaction H⁺ was displaced by Ag from HNO₃.

Conclusion

The reaction between HNO₃ and Ag₂O gives us an electrolytic salt silver nitrate along with water, where we can estimate the amount of nitrate. This reaction is an acid-base and irreversible reaction. This reaction is used for the production of silver nitrate.