15 Facts on H2SO4 + NaH2PO4: What, How to Balance & FAQs

H₂SO₄ is a mineral acid, and NaH₂PO₄ is a sodium salt. Let us venture through the chemical reaction between H₂SO₄ and NaH₂PO₄ in depth.

The reaction between H₂SO₄ and NaH₂PO₄ is a multistep reaction. Concentrated H₂SO₄ is a highly corrosive acid. Pure Sulfuric acid is colorless and oily in nature. NaH₂PO₄, also known as Monosodium Phosphate is an industrial chemical. It is found in anhydrous, mono and dihydrate forms.

In this article, we will go through some important aspects, such as the reaction type, balancing equation, reaction enthalpy, ionic equation and some other crucial points.

What is the product of H₂SO₄ and NaH₂PO₄?

Sodium Bisulfate (NaHSO₄), Sodium Sulfate (Na₂SO₄) and Phosphoric acid (H₃PO₄) are formed when H₂SO₄ reacts with NaH₂PO₄ .

• H₂SO₄ + NaH₂PO₄ ==> NaHSO₄ + H₃PO₄ (1^st step)
• NaHSO₄ + NaH₂PO₄ <==> Na₂SO₄ + H₃PO₄  (2^nd step)

What type of reaction is H₂SO₄ + NaH₂PO₄?

H₂SO₄ + NaH₂PO₄ is a reversible reaction, a type of stepwise reaction, since it consists of two steps.

How to balance H₂SO₄ + NaH₂PO₄?

The reaction for H₂SO₄ + NaH₂PO₄ is balanced using the following steps.

H₂SO₄ + NaH₂PO₄ ==> NaHSO₄ + H₃PO₄  (1^st step)

NaHSO₄ + NaH₂PO₄ <==> Na₂SO₄ + H₃PO₄  (2^nd step)

• The number of atoms of reactants and products side must be noted down.

• For the 1^st step, the no. of atoms of Na, H, S and O on LHS and RHS is same.

• For the 2nd step also, the no. of atoms of Na, H, S and O are same.

• It is observed that the equations are already balanced since the number of atoms on LHS and RHS for both equations is the same, and there is no need to multiply by the stoichiometric coefficient.

• Finally, the balanced equations are:

• H₂SO₄ + NaH₂PO₄ ==> NaHSO₄ + H₃PO₄ 

• NaHSO₄ + NaH₂PO₄ <==> Na₂SO₄ + H₃PO₄ 

H₂SO₄ + NaH₂PO₄ titration

Titration is not feasible since the reaction H₂SO₄ + NaH₂PO₄ comprises multiple steps.

H₂SO₄ + NaH₂PO₄ net ionic equation

The net ionic equations for H₂SO₄ + NaH₂PO₄ are:

For 1^st step of reaction

• 2H⁺_(aq)+SO₄^2-_(aq) +Na⁺_(aq)+ H₂PO₄^–_(aq) ==> Na⁺_(aq) +HSO₄^–_(aq)+3H⁺_(aq)+ PO₄^3-_(aq)

For 2^nd  step of reaction

• Na⁺_(aq) +HSO₄^–_(aq)+ Na⁺_(aq)+ H₂PO₄^–_(aq) <==> 2Na⁺_(aq)+ SO₄^2-_(aq)+ 3H⁺_(aq)+ PO₄^3-_(aq)

Following steps are used to derive the net ionic equations.

• Firstly, write the chemical equations with the physical states of the chemical species.
• H₂SO_4(aq) + NaH₂PO_4(aq) ==> NaHSO_4(aq) + H₃PO_4(aq)  (1^st step)
• 2H⁺_(aq)+SO₄^2-_(aq) +Na⁺_(aq)+ H₂PO₄^–_(aq) ==> Na⁺_(aq) +HSO₄^–_(aq)+3H⁺_(aq)+ PO₄^3-_(aq)
• NaHSO_4(aq) + NaH₂PO_4(aq) <==> Na₂SO_4(aq) + H₃PO_4(aq)  (2^nd step)
• Na⁺_(aq) +HSO₄^–_(aq)+ Na⁺_(aq)+ H₂PO₄^–_(aq) <==> 2Na⁺_(aq)+ SO₄^2-_(aq)+ 3H⁺_(aq)+ PO₄^3-_(aq)
• Thus, there will not be a net ionic reaction for such type of multistep reaction since the second step is not unidirectional.

H₂SO₄ + NaH₂PO₄ conjugate pairs

• H₂SO₄ gives rise to H₃O⁺ (Conjugate acid) and HSO₄^– (Conjugate base) in the presence of water.
• NaH₂PO₄ produces H₂PO₄^– as its conjugate base.

H₂SO₄ and NaH₂PO₄ intermolecular forces

• In H₂SO₄ , Van der Waals dispersion forces, dipole-dipole interactions and Hydrogen bonding are the three main intermolecular forces present.
• Ionic bond is the intermolecular force present in NaH₂PO₄.

H₂SO₄ + NaH₂PO₄ reaction enthalpy

There is no literature available about enthalpy for the reaction of H₂SO₄ and NaH₂PO₄.

Is H₂SO₄ + NaH₂PO₄ a buffer solution?

H₂SO₄ + NaH₂PO₄ is not a buffer solution since H₂SO₄ is a strong acid and NaH₂PO₄ is salt of H₃PO₄ with strong base NaOH which are unable to maintain the pH.

Is H₂SO₄ + NaH₂PO₄ a complete reaction?

H₂SO₄ + NaH₂PO₄ is not a complete reaction since the reaction is not reaching equilibrium in the 2^nd step:

NaHSO_4(aq) + NaH₂PO_4(aq) <==> Na₂SO_4(aq) + H₃PO_4(aq) .

Is H₂SO₄ + NaH₂PO₄ an exothermic or endothermic reaction?

There is no literature elaborating exothermic or endothermic nature for the reaction of H₂SO₄+NaH₂PO₄.

Is H₂SO₄ + NaH₂PO₄ a redox reaction?

H₂SO₄ + NaH₂PO₄ is not a redox reaction because there is no change in the oxidation state of the chemical species present in the reaction.

Is H₂SO₄ + NaH₂PO₄ a precipitation reaction?

H₂SO₄ + NaH₂PO₄ is not a precipitation reaction because acidic pH (due to H₂SO₄) will increase the solubility of NaH₂PO₄ , whose anion dihydrogen phosphate (H₂PO₄^– ) is the conjugate base of a weak acid.

Is H₂SO₄ + NaH₂PO₄ reversible or irreversible reaction?

H₂SO₄ + NaH₂PO₄ is reversible in nature because it is a multistep reaction which attains dynamic equilibrium.

Is H₂SO₄ + NaH₂PO₄ displacement reaction?

H₂SO₄ + NaH₂PO₄ is not a displacement reaction because it is reversible in nature.

Conclusion:

The reaction between H₂SO₄ + NaH₂PO₄ attains equilibrium but the forward and reverse reaction keep on going at the same rate. Sodium Sulfate is used in Kraft process of paper pulping. While Sodium Bisulfate is used in lowering the pH value and Phosphoric acid used in fertilizers.

Vishakha Awalegaonkar

Hello…. I am Vishakha Awalegaonkar. I have done my Master’s in Analytical Chemistry. Currently, I am working for a leading Company in the consumer health sector. Apart from that, I am also a Japanese language trainer. Feel free to reach me on LinkedIn: