15 Facts on HF + NaHSO3 : What, How To Balance & FAQs

A chemical reaction can be either reversible or irreversible reaction. Let us discuss about the reaction of HF and NaHSO3 and it’s various facts.

Hydrogen fluoride is an electronegative compound which gets dissolved in water to give strong hydro fluoric acid . Sodium bisulphate or NaHSO3 is also called sodium hydrogen sulphate is a white or yellow crystalline solid substance. The dipole moment of HF is 1.86 D having 91.7 pm bond length.

NaHSO3 is used as food additives,reducing agents and as decomposer in textile industry. Let us discuss about HF + NaHSO3 with all its details.

What is the product of HF and NaHSO3

HF reacts with NaHSO3 to form sodium fluoride,NaF and Sulphurus acid, H2SO3.

HF + NaHSO3 ——> NaF + H2SO3

What type of reaction is HF + NaHSO3

HF + NaHSO3 is a double displacement reaction. In this reaction both the reactants HF and NaHSO3 exchange or displaces their respective cations to form the products sodium fluoride and Sulphurus acid.

How to balance HF + NaHSO3

The physical states of reactants and products are usually indicated in brackets as subscript . The unbalanced equation of HF + NaHSO3

HF + NaHSO3 ——–> NaF + H2SO3

  • Assigning certain coefficients to both reactants and products
  • a HF + b NaHSO3 ——> c NaF + d H2SO3
  • An equation is made with the above equation
  • H= a= b = 2d, F=a =c, S =b = d, O=3b = 3d, Na = b= c
  • The equation made is a+ b = 2d, a= c, b= d, 3b = 3d, b= c
  • Solve the above equation using gauss elimination method. The values of coefficients is a =1, b= 1, c= 1, d= 1
  • The balanced equation of HF + NaHSO3 is
  • HF + NaHSO3 ——-> NaF + H2SO3

HF + NaHSO3 titration

HF + NaHSO3 titration can be performed using suitable indicator.


Conical flask, burette, indicator, pipette.


Methyl orange


  • A standard solution of sodium hydrogen sulphate is prepared by dissolving NaHSO3 in water.
  • A definite amount of solution is pipetted into a conical flask and add methyl orange indicator.
  • The solution in conical flask is then titrated against HF taken in burette.
  • The titration is continued until the color change is observed.
  • Note down the values and respective calculations done to determine its molarity, molality etc.

HF + NaHSO3 net ionic equation

The net ionic equation of HF and NaHSO3

HF + H+ +SO32-——-> F + H2SO3

Both HF and H2SO3 does not dissociate while NaF and NaHSO3 undergoes dissociation.

HF + NaHSO3 conjugate Pairs

HF + NaHSO3 has conjugate pairs.

  • The conjugate base of HF is F or fluoride.
  • The Conjugate acid of HF is fluoronium.
  • The Conjugate acid of NaHSO3 is H2SO3.

HF and NaHSO3 intermolecular forces

The intermolecular forces exist in between HF + NaHSO3 is

  • Dipole dipole interaction , hydrogen bonding and London dispersion forces are observed in HF.
  • In NaHSO3 also covalent bond is observed between sulphur and oxygen, hydrogen bond and coordinate bonds are also seen.
hf + nahso3
Structure of NaHSO3

HF + NaHSO3 reaction enthalpy

The reaction enthalpy of HF + NaHSO3 is 192.94 KJ/mol.

  • The enthalpy of formation of HF, NaHSO3, NaF and H2SO3 is -14.99, -1387.1, -573.6 and -635.55 kJ/mol respectively.
  • Hence enthalpy is {-14.99 + -635.55-(-14.99 + -1387.1)}.

Is HF + NaHSO3 a buffer solution

HF + NaHSO3 is not a buffer solution. Here HF is a weak acid and NaHSO3 is an acidic salt. Mixing both these will not make a buffer solution.

Is HF + NaHSO3 a complete reaction

HF + NaHSO3 is a complete reaction. The reaction takes place to form sodium fluoride,NaF and Sulphurus acid,H2SO3. Both are stable products. NaF is a water soluble substance which is basic in nature.

Is HF + NaHSO3 an exothermic or endothermic reaction

HF + NaHSO3 is an endothermic reaction. In this reaction heat energy is absorbed not liberated. So it is an endothermic reaction with positive value of enthalpy.

Is HF + NaHSO3 a redox reaction

HF + NaHSO3 is not a redox reaction. Because the oxidation number of reactants and products retain as it is before and after the reaction. So it’s not a redox reaction.

Is HF + NaHSO3 a precipitation reaction

HF + NaHSO3 is reaction doesn’t form any precipitate. It is because the product formed sodium fluoride is a water soluble substance.

Is HF + NaHSO3 reversible or irreversible reaction

HF + NaHSO3 is an irreversible reaction. The reaction can’t be reversed to yield back its reactants

Is HF + NaHSO3 a displacement reaction

HF + NaHSO3 is a double displacement reaction where both the reactants displaces the cations to yield the products.


The strong attraction between hydrogen and Fluorine in HF is due to hydrogen bonding. NaHSO3 is a solid substance having 104.061 g/mol molar mass with 1.48 g/cm3 density. The melting point and boiling point of NaHSO3 is 1500 C and 3150 C respectively.