1. A student was asked to make up a 10% w/w solution of sodium carbonate. Calculate the amount of solute and solvent required to prepare that solution?
Molality= (mass of solute*1000)/(molar mass*mass of solvent)
Now see, 10% Na2CO3 means
100gram solution contains 10gram Na2CO3
Mass of solute=10 gram
Mass of solvent= 100–10=90gram
Molar mass of Na2CO3=106gram
Hence putting values in formula we get