How to Calculate Mass Percent and Molality of a Solution
Question:
How can we calculate the mass percent of a given solute in a solution?
What is the formula to determine the molality of a solution?
Answer:
a) The mass percent of sucrose in the solution is 12.49%.
b) The molality of the solution is approximately 5.47 mol/kg.
To calculate the mass percent of a solute in a solution, you need to know the mass of the solute and the total mass of the solution. The formula for mass percent is:
Mass percent = (Mass of solute / Total mass of solution) * 100For calculating the molality of a solution, you first need to determine the moles of the solute and the mass of the solvent in kilograms. The formula for molality is:
Molality = (Moles of solute / Mass of solvent in kg)Let's break down the calculations step by step:
a) Mass Percent of Sucrose:
Total mass of the solution = Mass of sucrose + Mass of water
Total mass = 50.4 g + 0.332 kg * 1000 g/kg = 50.4 g + 332 g = 382.4 g
Now, you can calculate the mass percent of sucrose:
Mass percent = (Mass of sucrose / Total mass) * 100
Mass percent = (50.4 g / 382.4 g) * 100 ≈ 12.49%
b) Molality of the Solution:
First, calculate the moles of sucrose using its molar mass:
Molar mass of sucrose = (12 * 12.01 g/mol) + (22 * 1.01 g/mol) + (11 * 16.00 g/mol) = 342.33 g/mol
Moles of sucrose = 50.4 g / 342.33 g/mol ≈ 0.1471 mol
Now, calculate the molality of the solution:
Molality = (0.1471 mol / 0.332 kg) ≈ 5.47 mol/kg
Therefore, the mass percent of sucrose in the solution is approximately 12.49%, and the molality of the solution is approximately 5.47 mol/kg.