The reaction between HBr and PbSO4 is an example of double displacement reaction (two reactants combine to yield two different products). Let us study this reaction in more detail.
PbSO4 (Anglesite) is a white crystalline salt insoluble in water whereas HBr is a strong acid highly soluble in water. When both are allowed to react with each other exchange of ions occur between both compounds.
HBr is a polar covalent compound capable of forming hydrogen bond and PbSO4 is a solid ionic compound. The molar masses of HBr and PbSO4 are 80.9g/mol and 303.26g/mol respectively.
What is the product of HBr+PbSO4
Lead dibromide (PbBr2) and sulphuric acid (H2SO4) are the products of reaction between Hydrogen bromide (HBr) and lead sulphate (PbSO4).
2HBr + PbSO4 = PbBr2 + H2SO4
What is the type of reaction of HBr and PbSO4
The reaction between HBr and PbSO4 is a Double Displacement reaction.
How to balance HBr+PbSO4?
Steps to balance the reaction between HBr and PbSO4 –
- Write the reactant on the left hand side and product on the right side each separated by arrow or equal sign : HBr + PbSO4 = PbBr2 + H2SO4
- Write the physical states of all the reactants and products in small bracket on the right side: HBr (aq) + PbSO4 (s) = PbBr2 (s) + H2SO4 (aq)
- Count the number of moles of all the atoms or ions for both sides of reaction.
| Reactant side | Product side |
| H 1- = 1 | H 1- = 2 |
| Br 1- = 2 | Br 1- = 2 |
| SO4 2- = 1 | SO4 2- = 1 |
| Pb 2+ = 1 | Pb 2+ = 1 |
- Multiply any whole number either to respective reactant or product or both to make the number of moles equal for all ions on both side of chemical equation.
- Here if we multiply 2 with HBr so that the number of moles for both H and Br will become equal on both sides of reaction.
- So the overall balanced equation of the reaction having equal moles of each element on both reactant and product side is given by: 2HBr (aq) + PbSO4 (s) = PbBr2 (s) + H2SO4 (aq)
HBr+PbSO4 titration
Titration of HBr and PbSO4 is not possible as HBr is strong water soluble acid while PbSO4 is a sparingly soluble salt in aqueous medium.
HBr+PbSO4 net ionic equation
The net ionic equation for reaction between HBr and PbSO4 is given by,
2H+ + 2Br – + Pb2+ + SO42- = PbBr2 + 2H+ + SO42-
2Br – + Pb2+ = PbBr2
- First of all both HBr and PbSO4 dissociate into their respective ions.
- The common ions from both reactant and product side are cancelled to yield the net ionic equation.
HBr+PbSO4 conjugate pairs
The conjugated pairs for the reaction between HBr and PbSO4 are-
- The Conjugate base of HBr = Br–
- The Conjugate acid of SO42-= HSO42-
HBr and PbSO4 intermolecular forces
HBr and PbSO4 reaction has the following intermolecular forces,
- In case of HBr molecule Dipole- dipole interaction occurs while in case of PbSO4 the interaction is ionic in nature.
- In HBr the electronegativity values for H and Br are 2.2 and 2.96 respectively. The molecule having negative charged electron slightly towards the bromine atom imparting negative charge to it while the hydrogen becomes positively charged.
- In PbSO4 transfer of electrons occurs from Pb to SO4 2- resulting in a strong ionic bond.
HBr+PbSO4 reaction enthalpy
The Enthalpy of a reaction is -161.6 kJ and can be calculated by finding the difference between the heat of formation of both product and reactant. For the reaction of HBr and PbSO4 the enthalpy of formation has been listed below-
- HBr = 36.23 kJ/mol
- PbSO4 = 919.94 kJ/mol
- PbBr2 = 244.8 kJ/mol
- H2SO4 = 909.27 kJ/mol
Enthalpy of reaction = (244.8 + 909.27) – (36.23 × 2 + 919.94) = -161.6 kJ
Is HBr+PbSO4 a buffer solution
HBr and PbSO4 do not form a buffer solution as HBr is a strong acid and PbSO4 is also salt of a strong acid i.e. H2SO4.
Is HBr+PbSO4 a complete reaction
HBr+PbSO4 is a complete reaction as the product formed in the reaction i.e. PbBr2 is a stable precipitate and H2SO4 is strong acid capable of complete dissociation.
Is HBr+PbSO4 an exothermic or endothermic reaction
The reaction between HBr and PbSO4 is exothermic in nature as the difference in enthalpy of product and reactant is negative (-161.6 kJ).
Is HBr+PbSO4 a redox reaction
The reaction between HBr and PbSO4 can be termed as a redox reaction as there is no change in the oxidation state of any atom in the reaction.
Is HBr+PbSO4 a precipitation reaction
The reaction HBr+PbSO4 precipitation reaction. The product PbBr2 formed is insoluble and hence appears like a insoluble solid in the reaction medium.
Is HBr+PbSO4 reversible or irreversible reaction
The reaction HBr+PbSO4 is an irreversible reaction as the products formed are stable and cannot be reversed back to their prior state.
Is HBr+PbSO4 displacement reaction
The reaction is an example of displacement reaction because in the reaction between HBr and PbSO4 both Br1- and SO42- are exchanged between HBr and PbSO4.
Conclusion
Two moles of HBr and one mole of PbSO4 react with each other in an exothermic manner giving PbBr2 and H2SO4 as product. PbBr2 being insoluble in water precipitates out of the reaction mixture. Hence the reaction can be termed as both Double Displacement and Precipitation reaction.
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