Posted by Shai on .
What is the molality of a 0.065M solution of ethyl alcohol in water at 25 degrees Celcius? (Assume the density of the solution at such low conentration is equal to that of water at 25 degrees Celcius, 0.997 g./mL)
Note the correct spelling of celsius.
0.065 M = 0.065moles/L solution.
Density of the solution = 0.997 g/mL; therefore, 1 L of solution has a mass of m = volume x density = 1000 x 0.997 = 997 grams.
How much of that is EtOH. 0.065moles x 46 g/mol = 2.99 grams EtOH. The total mass is 997; therefore, the water present must be 997-2.99 = ??g
molality = moles/kg solvent