A laboratory experiment on preparation of 3PbO·PbSO4·H2O using less solvent solid state reaction for undergraduate students

Less solvent solid state reactions are reactions of solids with help of a little amount of solvent in ordinary stirring reactors. Due to the limited amount of solvent, only part of the substances can dissolve in the solvent, and the solvent can be regarded as a transport agent that makes the reactants contact easily. Here, we present an experiment about less solvent solid state reaction that enables students to use β-PbO and PbSO₄ to produce 3PbO·PbSO₄·H₂O (tribasic lead sulfate, usually short as 3BS) in 2 h with its reaction monitored and product characterized with X-ray diffraction. By combining their experiment data with the thermodynamic analysis in the pre-lab lecture, students can understand why solution reactions reach equilibriums eventually while solid state reactions reach 100% completion, and how to get rid of the diffusion difficulty of solid state reactions. Meanwhile, exposure to this experiment can stimulate students to explore techniques for greener chemical processes other than solution reactions.