Phosphoric Acid Second Neutralization

H₃PO₄ + 2NaOH → Na₂HPO₄ + 2H₂O

Overview

Partial neutralization of phosphoric acid with two equivalents of NaOH produces disodium hydrogen phosphate. This salt forms solutions near pH 9.2 and is one component of the phosphate buffer system widely used in biochemistry. The dibasic form is the predominant species at physiological pH.

Participants

Role	Substance	Coefficient	State
Reactant	Phosphoric Acid H₃PO₄	1	(aq)
Reactant	Sodium Hydroxide NaOH	2	(aq)
Product	Water H₂O	2	(l)

Everyday Example

Phosphate buffer saline (PBS) used in biology labs contains disodium hydrogen phosphate to maintain pH around 7.4.

Industrial Importance

Disodium hydrogen phosphate is used in food processing as an emulsifier, in water treatment, and in pharmaceutical formulations as a buffering agent.

Properties

Type: Acid-Base
Reversible: No
Energy: Exothermic
ΔH: -112.0 kJ/mol

Related Reactions

Acetic Acid and Sodium Acetate Buffer System Acetic Acid and Sodium Hydroxide Neutralization Acetic Acid Dissociation in Water Aluminum Chloride and Chloride Ion (Lewis Acid-Base) Aluminum Hydroxide as Amphoteric Acid with NaOH Aluminum Hydroxide as Amphoteric Base with HCl Ammonia and Ammonium Chloride Buffer System Ammonia and Hydrochloric Acid Ascorbic Acid and Sodium Hydroxide Barium Hydroxide and Ammonium Thiocyanate (Endothermic)

Frequently Asked Questions

What is the equation for Phosphoric Acid Second Neutralization?

The balanced equation is: H₃PO₄ + 2NaOH → Na₂HPO₄ + 2H₂O.

What type of reaction is Phosphoric Acid Second Neutralization?

Phosphoric Acid Second Neutralization is a acid-base reaction.

Is Phosphoric Acid Second Neutralization exothermic or endothermic?

Phosphoric Acid Second Neutralization is exothermic (releases energy). The enthalpy change (ΔH) is -112.0 kJ/mol.