1. Calculate the molar concentration of ethanol in an aqueous solution that contains 2.30 g of C₂H₅OH (46.07 g/mol) in 3.50 L solution.
The molarity or molar concentration is defined as the number of moles of the solute divided the volume of solution in L.
Molarity = moles of solute/(volume of solution in L)
We are given the volume of solution in L (3.50 L).
Volume of solution in L = 3.50 L
To answer our problem we have to find the number of moles of ethanol. We know the mass of solute that is dissolved in the aqueous solution. We have 2.30 g of ethanol.
mass of ethanol = 2.30 g
We have to go from the mass of ethanol to moles of it. Usually when we have to convert mass into moles we use the molar mass. The molar mass of ethanol is 46.07 g/mol.
molar mass of ethanol = 46.07 g/mol
With the molar mass and the mass of ethanol we can find the number of moles of it. And then we can find the molarity of the solution.
number of moles of ethanol = 2.30 g/(46.07 g/mol)
number of moles of ethanol = 0.0500 moles
Molarity = moles of solute/(volume of solution in L)
Molarity = 0.0500 moles/3.5 L
Molarity = 0.0143 M
Answer: the molar concentration of ethanol is 0.0143 M