Question

If you dissolve 2.00 g of Ca(NO3)2 in 750 g of water, what is the molality of the solution?

Answer 1

Answer – We are given, mass of Ca(NO₃)₂ = 2.00 g , mass of water = 750 g

First we need to calculate moles of Ca(NO₃)₂

Moles of Ca(NO₃)₂ = 2.00 g/ 164.088 g.mol^-1

                                = 0.0122 moles

Now we need to convert mass of water g to kg

We know

1 g = 0.001 kg

So, 750 g = ?

= 0.750 kg

So, molality = moles of solute / kg of solvent

                    = 0.0122 moles / 0.750 kg

                     = 0.0162 m