If 35.0mL of ethanol,C2H5OH, were added to 65.0mL of water, what is the percent by volume of the solution?

1 Answer
Apr 3, 2018

Percent by volume is basically #("volume x")/"total volume"xx100#
See below


Ethanol, ugh. Always a caveat with ethanol. 50ml of ethanol and 50ml of water don't make 100mL...but rather about 95mL (thanks, entropy). The intermolecular interactions reduce the volume due to solvation/water caging, etc.

That being said, we are going to assume these volumes will be added together to make 100mL (if you want to have a more precise answer, there is probably a table of volume reductions for specific concentrations of ethanol - maybe google).

Percent volume of Ethanol: #("volume ethanol")/"total volume"xx100#

#("35mL")/"100mL"xx100# = 35%