The molarity and the molality of a solution prepared by dissolving 2.00 g of ethanol C2H5OH with 99.0 g of water to give a final volume 101 mL are
______Molarity and _______molality.
How do I do this?
Remember the definitions. That's all you need.
molarity = # mols/L solution.
molality = # mols/kg solvent.
# mols = grams/molar mass.
To find the molarity and molality of the solution, you need to calculate the number of moles of solute (ethanol) and the mass of the solvent (water). Here's how you can do it:
1. Calculate the number of moles of ethanol (C2H5OH):
Molar mass of ethanol (C2H5OH) = (2 x 12.01 g/mol) + (6 x 1.01 g/mol) + (1 x 16.00 g/mol) = 46.07 g/mol
Number of moles of ethanol = mass of ethanol / molar mass of ethanol
Number of moles of ethanol = 2.00 g / 46.07 g/mol
2. Calculate the mass of water:
Mass of water = 99.0 g
3. Calculate the molarity of the solution:
Molarity (M) = moles of solute / volume of solution in liters
Volume of solution = 101 mL = 101 mL / 1000 mL/L = 0.101 L
Molarity (M) = number of moles of ethanol / volume of solution
4. Calculate the molality of the solution:
Molality (m) = moles of solute / mass of solvent in kilograms
Mass of water in kilograms = mass of water / 1000
Now, let's plug in the values into the formulas:
Molarity (M) = (2.00 g / 46.07 g/mol) / 0.101 L
Molality (m) = (2.00 g / 46.07 g/mol) / (99.0 g / 1000)
Simplify and calculate to find the values of Molarity and Molality.