Answer : The molality, mass/mass percent, and mass/volume percent are, 0.0381 mole/Kg, 25.67 % and 32.086 % respectively.
Solution : Given,
Density of solution = 1.25 g/ml
Molar mass of
(solute) = 95.21 g/mole
3.37 M magnesium chloride means that 3.37 gram of magnesium chloride is present in 1 liter of solution.
The volume of solution = 1 L = 1000 ml
Mass of
(solute) = 3.37 g
First we have to calculate the mass of solute.
![\text{Mass of }MgCl_2=\text{Moles of }MgCl_2\times \text{Molar mass of }MgCl_2](https://tex.z-dn.net/?f=%5Ctext%7BMass%20of%20%7DMgCl_2%3D%5Ctext%7BMoles%20of%20%7DMgCl_2%5Ctimes%20%5Ctext%7BMolar%20mass%20of%20%7DMgCl_2)
![\text{Mass of }MgCl_2=3.37mole\times 95.21g/mole=320.86g](https://tex.z-dn.net/?f=%5Ctext%7BMass%20of%20%7DMgCl_2%3D3.37mole%5Ctimes%2095.21g%2Fmole%3D320.86g)
Now we have to calculate the mass of solution.
![\text{Mass of solution}=\text{Density of solution}\times \text{Volume of solution}=1.25g/ml\times 1000ml=1250g](https://tex.z-dn.net/?f=%5Ctext%7BMass%20of%20solution%7D%3D%5Ctext%7BDensity%20of%20solution%7D%5Ctimes%20%5Ctext%7BVolume%20of%20solution%7D%3D1.25g%2Fml%5Ctimes%201000ml%3D1250g)
Mass of solvent = Mass of solution - Mass of solute = 1250 - 320.86 = 929.14 g
Now we have to calculate the molality of the solution.
![Molality=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Mass of solvent}}=\frac{3.37g\times 1000}{95.21g/mole\times 929.14g}=0.0381mole/Kg](https://tex.z-dn.net/?f=Molality%3D%5Cfrac%7B%5Ctext%7BMass%20of%20solute%7D%5Ctimes%201000%7D%7B%5Ctext%7BMolar%20mass%20of%20solute%7D%5Ctimes%20%5Ctext%7BMass%20of%20solvent%7D%7D%3D%5Cfrac%7B3.37g%5Ctimes%201000%7D%7B95.21g%2Fmole%5Ctimes%20929.14g%7D%3D0.0381mole%2FKg)
The molality of the solution is, 0.0381 mole/Kg.
Now we have to calculate the mass/mass percent.
![\text{Mass by mass percent}=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 100=\frac{320.86}{1250}\times 100=25.67\%](https://tex.z-dn.net/?f=%5Ctext%7BMass%20by%20mass%20percent%7D%3D%5Cfrac%7B%5Ctext%7BMass%20of%20solute%7D%7D%7B%5Ctext%7BMass%20of%20solution%7D%7D%5Ctimes%20100%3D%5Cfrac%7B320.86%7D%7B1250%7D%5Ctimes%20100%3D25.67%5C%25)
The mass/mass percent is, 25.67 %
Now we have to calculate the mass/volume percent.
![\text{Mass by volume percent}=\frac{\text{Mass of solute}}{\text{Volume of solution}}\times 100=\frac{320.86}{1000}\times 100=32.086\%](https://tex.z-dn.net/?f=%5Ctext%7BMass%20by%20volume%20percent%7D%3D%5Cfrac%7B%5Ctext%7BMass%20of%20solute%7D%7D%7B%5Ctext%7BVolume%20of%20solution%7D%7D%5Ctimes%20100%3D%5Cfrac%7B320.86%7D%7B1000%7D%5Ctimes%20100%3D32.086%5C%25)
The mass/volume percent is, 32.086 %
Therefore, the molality, mass/mass percent, and mass/volume percent are, 0.0381 mole/Kg, 25.67 % and 32.086 % respectively.