An aqueous solution is prepared by dissolving 0.1 mol of an ionic salt in 1.8 kg of water at 35 °C. The salt remains 90% dissociated in the solution. The vapour pressure of the solution is 59.724 mm of Hg. Vapor pressure of water at 35 °C is 60.000 mm of Hg. The number of ions present per formula unit of the ionic salt is ____.
Answer: 5
Solution
Let the ionic salt dissociate into ions per formula unit. At 90% dissociation, 0.1 mol of salt gives mol undissociated and mol ions. Total non-volatile particles = . Moles of water = mol.
Using relative lowering of vapor pressure:
Using relative lowering of vapor pressure:
JEE Advanced · 2022 · 28 Aug 2022 · Paper 2 · Integer answer