13 Facts on H2SO4 + P2O5: What, How To Balance & FAQs

Sulphuric acid (H₂SO₄) is a colourless, viscous liquid and phosphorus pentoxide (P₂O₅) is a strong dehydrating agent. Let us take a glance at how these two react to each other.

Phosphorus oxide is not as strong an acid as much as sulphuric acid; it is an acidic oxide that works well as a desiccating agent.

We will dive deep into the facts about reactions between H₂SO₄ and P₂O₅, like reaction enthalpy, type of reaction, conjugate pairs, intermolecular forces etc.,

What is the product of H₂SO₄ and P₂O₅

Sulphur trioxide and meta-phosphoric acids are formed when sulphuric acid (H₂SO₄) is heated in the presence of phosphorus pentoxide, which has to be taken in excess.

H₂SO₄ + P₂O₅ = SO₃ + HPO₃

What type of reaction is H₂SO₄ and P₂O₅

The reaction between H₂SO₄ and P₂O₅ is a double-displacement reaction.

How to balance H₂SO₄ and P₂O₅

The reaction between H₂SO₄ and P₂O₅ can be balanced using the steps mentioned below,

• Writing the general chemical equation:
• H₂SO₄ + P₂O₅ = SO₃ + HPO₃
• We need to check whether the number of atoms on the reactant and product side is equal. But as we can see, the number of hydrogens, oxygens and phosphorus need to be balanced throughout the equation.
• Therefore we will multiply a coefficient of 2 with metaphosphoric acid to get the new equation.
• H₂SO₄ + P₂O₅ = SO₃ + 2HPO₃
• Counting down the number of atoms present on both sides of the chemical equation;

Atoms	Number on reactant side	Number on product side
H	2	2
S	1	1
O	9	9
P	2	2

• As the number of atoms gets equated, the new balanced chemical equation is
• H₂SO₄ + P₂O₅ = SO₃ + 2HPO₃

H₂SO₄ and P₂O₅ titration

The titration between H₂SO₄ and P₂O₅ is not feasible as both are acids and thus the end-point during the titration cannot be determined.

H₂SO₄ and P₂O₅ net ionic equation

The net ionic equation for H₂SO₄ + P₂O₅ reaction is,

SO₄^2- (aq.) + P₂O₅ (aq.) = SO₃ (g) + PO₃^– (aq.)

• The general balanced equation for H₂SO₄ + P₂O₅ is
• H₂SO₄ + P₂O₅ = SO₃ + 2HPO₃
• Indicating the chemical states of each molecule
• H₂SO₄ (aq.) + P₂O₅ (aq.) = SO₃ (g) + 2HPO₃ (aq.)
• Split the soluble compounds into their respective ions.
• 2H⁺ (aq.) + SO₄^2- (aq.) + P₂O₅ (aq.) = SO₃ (g) + 2H⁺ (aq.) + PO₃^– (aq.)
• Cancel out the ions which are present on both sides to get the net ionic equation.
• SO₄^2- (aq.) + P₂O₅ (aq.) = SO₃ (g) + PO₃^– (aq.)

H₂SO₄ and P₂O₅ conjugate pairs

In the following reaction,

H₂SO₄ + P₂O₅ = SO₃ + 2HPO₃

• The Conjugate pair for reactant H₂SO₄ is HSO₄^–
• The Conjugate pair for HPO₃ is PO₃^–

The other two, i.e., P₂O₅ and SO₃, do not have any conjugate pairs because they lack hydrogen in their chemical formula.

H₂SO₄ and P₂O₅ intermolecular forces

The H₂SO₄ + P₂O₅ reaction has the following intermolecular forces between the molecules,

Molecules	Intermolecular forces
H2SO4	1. Van der Waals dispersion forces 2. dipole-dipole interactions
P2O5	Weak van der waal forces
SO3	London-dispersion forces

Is H₂SO₄ and P₂O₅ a buffer solution

H₂SO₄ + P₂O₅ reaction cannot yield a buffer solution as both chemicals have an acidic nature having variations in the strength of acidity. That is why if more acid is added to the solution, the pH value will decrease further, which should not happen in the case of a buffer solution.

Is H₂SO₄ and P₂O₅ a complete reaction

H₂SO₄ + P₂O₅ reaction is a complete reaction as sulphuric acid, and phosphorus pentoxide is completely used to form meta-phosphoric acid with sulphur trioxide.

Is H₂SO₄ and P₂O₅ an exothermic or endothermic reaction

H₂SO₄ + P₂O₅ reaction is an endothermic chemical reaction because heat is needed at the beginning of the reaction to initiate the process.

Is H₂SO₄ and P₂O₅ a redox reaction

H₂SO₄ + P₂O₅ reaction is not a redox reaction because the oxidation states of atoms have remained unchanged throughout the process.

Is H₂SO₄ and P₂O₅ a precipitation reaction

H₂SO₄ + P₂O₅ reaction is not a precipitation reaction as H₂SO₄ and P₂O₅ reaction do not yield any precipitates.

Is H₂SO₄ and P₂O₅ reversible or irreversible reaction

H₂SO₄ + P₂O₅ reaction is irreversible reaction because the SO₃ released cannot be added back to the reaction until an immense high pressure is applied, which is not possible normally.

Is H₂SO₄ and P₂O₅ displacement reaction

H₂SO₄ + P₂O₅ reaction is a double-displacement reaction. Here, P₂O₅ acting as a dehydrator removes water from sulphuric acid to form meta-phosphoric acid.

Conclusion

The article concludes that both sulphuric acid and phosphorus pentoxide are reacting with each other being acids and P₂O₅ is a stronger dehydrating agent than sulphuric acid. These chemicals have several industrial and laboratory importance.