Question

9.8g potassium dicromate crystals are present in
2.5 litres of its solution Calculate the molality of
present
the solution​

Answer 1

Answer:

Molality or Molal concentration is a measure of the concentration of a solute in a solution given as a ratio of the amount of substance (in moles) in a specified amount of mass of the solvent.  

Formula for Molality is a s follows:

molality = moles of solute / mass of solvent (kg) ,

Find moles of Potassium carbonate,

molar mass = 138, mass = 2.5

moles  = mass / molar mass  ,

          = 2.5 / 138

          =  0.01812    

Find mass of the solvent ,

0.85 g/ml is 0.85kg/liter (conversion factor is 1000) ,

Therefore 1 liter will have 850g of the solution or 0.85kg ,

The molality will be:

m = moles of solute/ mass of solvent

 = 0.01812/ 0.85

 = 0.02132 mol/kg