Caesium hydrogen sulfate

Caesium hydrogen sulfate is an ionic compound with formula CsHSO₄.

CsHSO₄ is synthesized via a 1:1 molar reaction between Cs₂SO₄ and H₂SO₄. Both compounds are dissolved in DI water, and placed in a 60 °C oven with warm air flowing over the top of the mixing beaker. Once the solution is at half of its initial volume it is cooled to 5 °C. At this point there will be four molecules in the solution: Cs₂SO₄, H₂SO₄, CsHSO₄, and H₂O. At 5 °C only CsHSO₄ will precipitate into a crystalline solid. This makes for easy separation by filtration. The remaining wet CsHSO₄ can be dried in a vacuum dedicator.