A solution of ethanol in water is prepared by dissolving 61.0 mL of ethanol (density = 0.79g/mL) in enough water to make 280.0 mL of solution. What is the molarity of the ethanol in this solution?
definition of molarity = #mols/L.
mass ethanol = m = volume x density = 61.0 mL x 0.79 g/mL =?? grams.
mols ethanol = ??g/molar mass ethanol.
Liters = 0.280.
61.0 mL x 0.79 g/mL = 48.19 g
48.19 g / 46.0 molar mass = 1.05 mol
1.05 mol / .280 L = 3.74 M
To find the molarity of ethanol in the solution, we need to determine the number of moles of ethanol present and then divide that by the volume of the solution.
First, calculate the mass of ethanol in the solution:
Mass = volume x density = 61.0 mL x 0.79 g/mL = 48.19 g
Next, find the number of moles of ethanol:
Moles = Mass / Molar mass
Molar mass of ethanol (C2H5OH) = 46.0 g/mol
Moles = 48.19 g / 46.0 g/mol = 1.05 mol
Finally, calculate the molarity of ethanol:
Molarity = Moles / Volume
Volume = 280.0 mL = 0.280 L
Molarity = 1.05 mol / 0.280 L = 3.74 M
Therefore, the molarity of ethanol in this solution is 3.74 M.