15 Facts on HF + Fe2O3: What, How to Balance & FAQs

Hydrofluoric acid which is a weak acid reacts with ferric oxide which is a amphoteric oxide to undergo neutralization reaction. Let us now discuss the reaction: HF + Fe₂O_3.

Hydrogen fluoride (HF) is a colourless solution that acts as a weak acid. It does not dissociate in water completely. Ferric oxide, also called Hematite, is a reddish-brown odorless solution prepared by oxidation of iron. It is an amphoteric oxide naturally occurring in rocks having both acidic and basic properties.

In the following article we will discuss about the reaction, method of balancing, intermolecular forces, ionic equation, and various other facts about the reaction between HF and Fe₂O₃.

What is the product of HF and Fe₂O₃?

Ferric fluoride( FeF₃) is obtained as the salt along with water after the reaction of hydrofluoric acid and ferric oxide.

HF + Fe₂O₃ = H₂O + FeF₃

What type of reaction is HF + Fe₂O₃?

The reaction HF + Fe₂O₃ is an acid-base neutralization reaction, where HF is weak acid and Fe₂O₃ is an amphoteric oxide.

How to balance HF + Fe₂O₃?

The reaction HF + Fe₂O₃ = H₂O + FeF₃ is not balanced.

 We have to balance the given equation in the following way:

• The reactants and the products are labeled by a, b, c, d and e variables to represent the unknown coefficients.

• aHF ₊ b Fe₂O₃= cH₂O + d FeF₃

• The same type of elements is rearranged together, and then the coefficients are equated.
• After rearranging by their stoichiometric proportion, we get

• Fe= 2a = d; O = 3a=c; H=b=2c; F=b=3d

• Now we use the Gaussian elimination method to determine the values of the coefficients
• We get a=1 , b=6  ,c=3  , d=2
• Hence  the overall balanced equation is:

• HF + 6Fe₂O₃ = 3H₂O + 2FeF₃

HF + Fe₂O₃ titration

The titration of Fe₂O₃ using HF is very difficult since HF is a strong acid and Fe₂O₃ is amphoteric in nature. Thus determination of end point in the titration process is very much difficult.

Apparatus

• Conical flask
• Beakers
• Filter Paper
• Bunsen Burner
• Silica Crucible

Chemicals Required

Hydroflouric acid, Dilute nitric acid, ammonia

Procedure

• The oxide is dissolved in the hydroflouric acid medium in a conical flask.
• The conical flask is heated and stirred with ammonia along with a few drops of dilute nitric acid.
• The medium is washed to keep away impurities. The solution is filtered and washed again.
• A sticky reddish precipitate is obtained which is soluble in dilute acids
• The precipitate is heated and dried to measure purity. A few pieces of filter paper are added and the process is repeated.
• The amount of Ferric oxide obtained is measured, and weight of Iron is found by mathematical calculation.
• The weight of Fe₂O₃ = Weight of the crucible along with the residue – Weight of the empty crucible.

HF + Fe₂O₃ net ionic equation

The net ionic equation for the reaction HF + Fe₂O₃ is –

H⁺ + F^– + 6Fe₂O₃ = 2H₂O+ 2FeF₃

The ionic equation is derived by using the following steps:

• Firstly the chemical states are indicated in the equation:

• HF (aq.) + 6Fe₂O₃ (s) = 3H₂O(l) + 2FeF₃ (s)

• Then the corresponding compounds are split into their ionic forms as follows:

• H⁺(aq) + F^–(aq) +6Fe₂O₃ (s) = 2H₂O(l) + 2FeF₃(s)

• The net ionic equation is:

• H⁺ + F^– + 6Fe₂O₃ = 2H₂O+ 2FeF₃

HF + Fe₂O₃ conjugate pairs

The conjugate pairs of HF + Fe₂O₃ are:

• The conjugate base for HF is F^– .
• There exists no conjugate pair for Fe₂O₃ because it is amphoteric in nature.

HF and Fe₂O₃ intermolecular forces

HF and Fe₂O₃ has the following intermolecular forces:

• There is a strong dipole-dipole interaction between the ions of HF molecule, since it is a polar molecule
• Fe₂O₃ is a ionic compound thus the ions has electrostatic force of attraction between them.

HF + Fe₂O₃ reaction enthalpy

HF+ Fe₂O₃ reaction enthalpy is -18.33 KJ/mol, and is calculated as follows.

The formula for enthalpy calculation is= Enthalpy of Product – Enthalpy of Reactant

• =[3x(-285.83)+2x(-989.6)]-[(-824.2)+6x(-332.36)
• =-2836.69+2818.36 KJ/mol
• = -18.33 KJ/mol

Is HF + Fe₂O₃ a buffer solution?

HF + Fe₂O₃ will not form a buffer solution because Fe₂O₃ acts as a strong base in presence of a weak acid HF. Thus property of a buffer solution is not maintained.

Is HF + Fe₂O₃ a complete reaction?

HF + Fe₂O₃ reaction is a complete neutralization reaction as FeF₃ is obtained as a salt for this reaction along with water.

Is HF + Fe₂O₃ an exothermic or endothermic reaction?

HF + Fe₂O₃ is an exothermic reaction. It is because of the negative value of enthalpy (-18.33 KJ/mol) which means heat is released during the reaction.

Is HF + Fe₂O₃ a redox reaction?

HF + Fe₂O₃ is not a redox reaction because the oxidation states of the elements remain same before and after completion of the reaction.

Is HF + Fe₂O₃ a precipitation reaction?

HF + Fe₂O₃ is a precipitation reaction since a pale greenish precipitate of FeF₃ is obtained after the completion of the reaction.

Is HF + Fe₂O₃ reversible or irreversible reaction?

HF + Fe₂O₃ is an irreversible reaction as it is an acid base reaction because FeF₃ , that is produced as a salt along with water at the end of the reaction, is slightly soluble in water thus making the reaction irreversible in nature.

Is HF + Fe₂O₃ displacement reaction?

HF + Fe₂O₃ is a double displacement reaction, where H of HF is displaced by Fe from Fe₂O₃ and also O from Fe₂O₃ is displaced by H of HF. Besides, it is an acid base neutralization reaction which is an example of displacement reactions.

Conclusion

Reaction of hydrofluoric acid with ferrous oxide results in the formation of ferric fluoride as a salt along with water from the acid-base neutralization reaction.

Bhaswati Ghose

Hello… , I am Bhaswati Ghose. I have completed my master’s from St. Xavier’s College, Ranchi. My specialization subject was organic chemistry. I’m working as a subject matter expert in chemistry.