Answer:
Density is: 1.05 g/ml
Mole fraction solute: 0.015
Mole fraction solvent: 0.095
Molarity: 0.80 M
Molality: 0.82 m
Explanation:
A typical excersise of solution.
It is more confortable to make a table for this.
| masss | volume | mol
solute | | |
solvent | | |
solution | | |
Let's complete, what we have.
| masss | volume | mol
solute | 10.8g | |
solvent | | 133 mL |
solution | | 137 mL |
We can first, know how many moles are 10.8 g
Molar Mass H3PO4 = 97.99 g/mol
Mass / Molar mass = mol
10.8 g / 97.99 g/m = 0.110 mol
Density of water is 1 g/ml (it is a very knowly value)
From this data, we can know water mass, solvent.
Density = mass / volume
1 g/ml = mass / 133 mL
Mass = 133 g
We can also have the moles, by the molar mass of water 18 g/m
133 g / 18 g/m = 7.39 mol
| masss | volume | mol
solute | 10.8g | | 0.110 mol
solvent | 133g | 133 mL | 7.39 mol
solution | 143.8g | 137 mL | 7.50 mol
Mass of solution will be solute mass + solvent mass
Moles of solution will be solute moles + solvent moles
Now we can calculate everything.
Molarity means mol of solute in 1 L of solution. (mol/L)
We have to convert 137 mL in L (/1000)
0.137L so → 0.110 m / 0.137L = 0.80 M
Molality means mol of solute in 1kg of solvent.
We have to convert 133g in kg (/1000)
0.133 kg so → 0.110 m/0.133 kg = 0.82 m
Density is mass / volume
Solution density will be solution mass / solution volume
143.8 g/137 mL = 1.05 g/m
Molar fraction is : solute moles / total moles or solvent moles/total moles.
You can also (x 100%) to have a percent of them.
Remember sum of molar fraction = 1
Molar fraction of solute = 0.110 mol / 7.50mol = 0.015
Molar fraction of solvent = 7.39 mol / 7.50 mol = 0.985
