posted by robert .
A saturated solution of ammonium sulfate, (NH4)2SO4, in water at 30 0C contains 78.0 g (NH4)2SO4 per 100.0 g H2O. What is the molality of this solution?
Molality = #mols/kg solvent
mols = g/molar mass
mols (NH4)2SO4 = 78.0g x (1 mol/molar mass) = ??
100.0 g H2O = 0.100 kg.
Plug and chug.
Post your work if you get stuck.