PbS + H2O2 = PbSO4 + H2O | Lead sulfide + Hydrogen Peroxide Reaction
Lead sulfide (PbS) reacts with hydrogen peroxide ( H2O2) and produce lead sulfate (PbSO4) and water as products.
This reaction is a redox reaction. In this tutorial, we will learn how to balance this reaction and uses of it.
PbS is a black precipitate and PbSO4 is a white precipitate.
Balancing the reaction of PbS + H2O2 = PbSO4 + H2O
We have to follow some rules (steps) to balance a redox reaction. You can learn how a redox reaction is balanced in next few minutes.
Oxidation numbers of elements in the reaction
Sulfide to sulfate - oxidation
Sulfide ion is oxidized to sulfate ion. Oxidation number of sulfur is increased from -2 to +6.
H2O2 reduction to H2O and SO42-
Oxygen atom is at -1 oxidation state in H2O2. Oxygen atom is reduced to -2 oxidation state. In H2O and SO42-, oxygen atom is at -2 oxidation state.
Equal number of oxidizing and reducing atoms
Number of sulfur atoms in both sides of the reaction is same (one). But number of oxygen atoms (reducing) is different. Two balance oxygen atoms, we make three H2O2 in the left and two H2O in the right side.
PbS + 3H2O2 = PbSO4 + 2H2O
Find differences of oxidation numbers
Sulfur atom at -2 oxidation state is oxidized to +6 oxidation state. So oxidation number change is 8.
Six oxygen atoms in H2O2 is at -1 are reduced to -2. So difference is 6.
8:6 ration is simplified as 4:3 . See the following figure.
Exchange oxidation number differences
Exchange oxidation numbers. Then simplified the stoichiometric coefficient.
Balanced Equation
PbS + 4H2O2 = PbSO4 + 4H2O
Uses of H2O2 + PbS reaction
Lead carbonate (PbCO3) is used as a white pigment. When air is polluted with hydrogen sulfide (H2S), lead carbonate reacts with H2S forming black PbS.
PbCO3 + H2S → PbS + CO2 + H2O
Therefore white colour of PbCO3 loses. To take back white colour, PbS is treated with H2O2.
Question
You are provided PbS and aqueous H2O2 solution to produce PbSO4, white precipitate. But after mixing two reactants, you cannot observe a white precipitate forming. So what may be the reasons?
H2O2 can be decomposed to H2O and O2. So there is no reaction between PbS and H2O2 to produce PbSO4.
PbS, H2O2 what are the states?
PbS is in solid state and H2O2 is in the aqueous state.
Can I dissolve PbS in dilute HCl acid?
With HCl, PbS is converted to PbCl2 white precipitate.
PbS + 2HCl → PbCl2 + H2S
But with excess HCl, white precipitate dissolves and produce colourless [PbCl4]2- aqueous solution.
PbS + H2O2 redox
Yes. Sulfide ion is oxidized and hydrogen peroxide is reduced. So PbS + H2O2 reaction is a redox reaction.
PbS oxidation number?
You know lead (Pb) is a metal and always form positive oxidation number and +2 is common in most compounds. Sulfide ion is at -2 oxidation state. So, Pb is at +2 oxidation state.
what is the oxidation number of pb in pbso4
PbSO4 salt does not have an overall charge. But Sulfate ion has -2 charge. To neutral that -2 charge, +2 charge should be there and it is given by Pb2+ ion. Therefore oxidation number of Pb in PbSO4 is +2.