15 Facts on HI + CH3OH: What, How To Balance & FAQs

The reaction between HI and CH₃OH is a classic example of Substitution Nucleophilic Bimolecular reaction (SN2).

Hydrogen iodide (HI) is a very strong acid while methanol (CH₃OH) can act as both acid and base (amphoteric). The molar mass of HI is 128g/mol and that of CH₃OH is 32.04g/mol. Both HI and CH₃OH are polar molecules capable of forming intermolecular hydrogen bonding.

Let us now look into the reaction between these two compounds and discuss the properties and outcomes in detail.

What is the product of HI and CH₃OH

Methyl iodide (CH₃I) and water (H₂O) is the product of reaction between HI and CH₃OH.

• CH₃OH + HI → CH₃I + H₂O

What type of reaction is HI + CH₃OH

The reaction between HI and CH₃OH is Substitution reaction where –OH is replaced by iodide of HI.

How to balance HI + CH₃OH

The reaction between HI and CH₃OH is balanced by following steps,

CH₃OH + HI → CH₃I + H₂O

• If we compare the number of moles of carbon, hydrogen , iodine and oxygen on both left and right side for the reaction we will see that the number is same and hence the reaction is balanced.

HI + CH₃OH titration

The titration between HI and CH₃OH cannot be carried out as CH₃OH is amphoteric in nature while HI is a strong acid.

HI + CH₃OH net ionic equation

The net ionic equation for HI + CH3OH is represented as,

H⁺ + I^– + CH₃O^– + H⁺ → CH₃I + H₂O

• HI dissociates into H⁺ and I^– while CH₃OH breaks down to CH₃O^– + H⁺.
• Lastly all combine to yield CH₃I and H₂O.

HI + CH₃OH conjugate pairs

The conjugate pairs of HI and CH₃OH are given by,

• The conjugate base of HI = I^–
• The conjugate base of CH₃OH = CH₃O^–

HI and CH₃OH intermolecular forces

The following intermolecular forces occur in case of both HI and CH₃OH,

• The dipole-dipole interaction due to electronegativity difference between Hydrogen and Iodine in case of HI and Carbon and Hydrogen in case of CH₃OH.
• Intermolecular hydrogen bonding also takes place for both the molecules.

HI + CH₃OH reaction enthalpy

The Enthalpy of reaction for HI + CH₃OH was found to be -48.24kJ/mol. The enthalpy of formation for both reactants and product is listed below,

• Enthalpy of formation for CH₃OH = -239kJ/mol
• Enthalpy of formation for HI = 26 kJ/mol
• Enthalpy of formation for CH₃I = 24.46kJ/mol
• Enthalpy of formation for H₂O = -285.7kJ/mol
• Enthalpy of reaction = [24.46-285.7]-[26-239] = -48.24 kJ/mol

Is HI + CH₃OH a buffer solution

HI and CH₃OH cannot form a buffer solution as HI is a strong acid while CH₃OH being amphoteric in nature cannot maintain the pH of the solution.

Is HI + CH₃OH a complete reaction

HI + CH₃OH is a complete reaction as HI is a strong acid capable of undergoing complete dissociation to give CH₃I and H₂O as products.

Is HI + CH₃OH an exothermic or endothermic reaction

The reaction between HI and CH₃OH is exothermic as the enthalpy of reaction is having a negative value and releases energy.

Is HI + CH₃OH a redox reaction

HI + CH₃OH reaction is not a redox reaction because there is no change in the oxidation state of the atoms.

Is HI + CH₃OH a precipitation reaction

HI + CH3OH reaction is not a precipitation reaction because CH3I is not a solid compound rather it is a dense liquid insoluble in water.

Is HI + CH₃OH reversible or irreversible reaction

The reaction between HI and CH₃OH is an irreversible reaction because the CH₃I is a stable product and cannot be reversed back to CH₃OH by disturbing the equilibrium.

Is HI + CH₃OH displacement reaction

The reaction HI + CH₃OH is a displacement reaction as the ions of both the reactants are exchanged with each other.

• OH of CH₃OH is replaced by I^– of HI.
• Hydride ions combine with the OH^– ions to form water.

Conclusion

Equimolar quantities of HI and CH₃OH combine with each other to form CH₃I and H₂O as products. CH₃OH is a water insoluble liquid and hence can be easily separated from the reaction mixture. This is an exothermic reaction where OH of methanol is displaced by I^– of hydrogen iodide.