15 Facts on H2SO4 + P4O10: What, How To Balance & FAQs

P4O10 is a strong desiccating or dehydrating agent even stronger than H2SO4. Let us see how it reacts with H2SO4 through this article.

Sulphuric acid (H2SO4) and tetraphosphorus decaoxide react to form acid and release gas. Tetraphosphorus decaoxide (P4O10) shows similar chemical properties like P2O5. Both are strong dehydrating agents of organic chemistry. But only P4O10 is strong enough to dehydrate H2SO4.

We will learn some useful facts about the H2SO4 + P4O10 reaction, like type of reaction, products formed, balanced chemical equation and reaction enthalpy in this article.

What is the product of H2SO4 and 4O10

Phosphoric acid (H3PO4) and sulphur trioxide (SO3) are the products of the H2SO4 + P4O10 reaction. The chemical equation for the reaction is,

H2SO4 + P4O10 = H3PO4 + SO3

What type of reaction is H2SO4 + 4O10

H2SO4 + P4O10 reaction is a double displacement reaction.

How to balance H2SO4 + 4O10

The balanced chemical equation for the H2SO4 + P4O10 reaction is,

6H2SO4 + P4O10 = 4H3PO4 + 6SO3

The following steps are used in derivation of the balanced chemical equation:

  • The unbalanced equation for H2SO4 + P4O10 reaction is,
  • H2SO4 + P4O10 = H3PO4 + SO3
  • To check if the moles of atoms present on the product side are equal to the reactant side or not. Here the number of H, P, O and S atoms are not equal.
  • Therefore, we multiply H2SO4, H3PO4 and SO3 with a coefficient of 6, 4 and 6 respectively.
  • Thus, the balanced chemical equation obtained is,
  • 6H2SO4 + P4O10 = 4H3PO4 + 6SO3

H2SO4 + 4O10 titration

Titration of H2SO4 and P4O10 is not possible as sulphuric acid is a strong acid and tetraphosphorus decaoxide is an acidic oxide that cannot be categorised in any titration procedure.

H2SO4 + 4O10 net ionic equation

The net ionic equation for H2SO4 + P4O10 reaction is,

2H+ (aq.) + SO42- (aq.) + P4O10 (aq.) = 2H+ (aq.) + PO32- (aq.) + SO3 (g)

The steps mentioned below are used in the derivation of the net ionic equation:

  • Note the general balanced chemical equation for H2SO4 and P4O10 reaction.
  • 6H2SO4 + P4O10 = 4H3PO4 + 6SO3
  • Specify each molecule with its chemical state (s, l, g or aq).
  • 6H2SO4 (aq.) + P4O10 (aq.) = 4H3PO4 (aq.) + 6SO3 (g)
  • Split the compounds which are strong enough to produce corresponding ions in their aqueous form to obtain the complete ionic equation.
  • 2H+ (aq.) + SO42- (aq.) + P4O10 (aq.) = 2H+ (aq.) + PO32- (aq.) + SO3 (g)
  • Eliminate the ions that are available on both sides.
  • SO42- (aq.) + P4O10 (aq.) = PO32- (aq.) + SO3 (g)

H2SO4 + 4O10 conjugate pairs

H2SO4 and P4O10 do not have any conjugate pairs.

  • The conjugate pair of H2SO4 is its conjugate base HSO42-.

H2SO4 and 4O10 intermolecular forces

  • H3PO4 also contains hydrogen bonding between their molecules.

H2SO4 + 4O10 reaction enthalpy

H2SO4 + P4O10 reaction enthalpy is 4955.7 kJ/mol. The  estimate values of standard enthalpy of formation for molecules in the reaction is,

MoleculesReaction enthalpy (in KJ/mol)
Reaction enthalpy of reactants and products

Reaction enthalpy (ΔHf) = Standard enthalpy of formation (product – reactant)

Thus, ΔHf = [6*(-395.72) + 4*(-277.4)] – [-2948 + 6*(-909.27)

ΔHf = 4955.7 kJ/mol.

Is H2SO4 + 4O10 a buffer solution

H2SO4 + P4O10 is not a buffer solution because a weak acid is necessary for forming a buffer solution but H2SO4 is a strong acid.

Is H2SO4 + 4O10 a complete reaction

H2SO4 + P4O10 is a complete reaction and cannot be proceeded further.

Is H2SO4 + 4O10 an exothermic or endothermic reaction

H2SO4 + P4O10 reaction is an endothermic reaction as the reaction enthalpy has a high positive value here.

Endothermic reaction graph

Is H2SO4 + 4O10 a redox reaction

H2SO4 + P4O10 reaction is not a redox reaction as the oxidation states of all the atoms are unchanged during the whole process.

Is H2SO4 + 4O10 a precipitation reaction

The H2SO4 + P4O10 reaction is not a precipitation reaction as no solid phase compound is formed at the end of this reaction.

Is H2SO4 + 4O10 reversible or irreversible reaction

H2SO4 + P4O10 reaction is an irreversible reaction because we cannot add the SO3 gas evolved during the process back into the reaction mixture.

Is H2SO4 + 4O10 displacement reaction

H2SO4 + P4O10 reaction is a double displacement reaction in which Hydrogen and Phosphorus atom displace each other to form new compounds.


This article concludes that both H2SO4 and P4O10 are very important compounds of chemistry. H2SO4 is a strong dehydrator and P4O10 is a stronger version of H2SO4. P4O10 reacts vigorously with water to produce phosphoric acid.

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