Question

The molecular weight of ethanol (CHgCHzOH) is 46 and its density is 0.789 g/cm3. A. \A4rat is the molarity of ethanol in beer that is 5% ethanol by volume? [Alcohol content of beer varies from about 4Vo (lite beer) to B% (stout beer).

Answer 1

molarity of ethanol in beer =
`(0.086* 1000)/(100)M=0.86M`

Step-by-step explanation:

5% ethanol in beer by volume means there are 5 mL of ethanol in 100 mL of beer.

Density is the ratio of mass to volume and
`1cm^(3)=1mL`

Mass of 5 mL of ethanol =
`(0.789* 5)g=3.945g`

Number of moles is the ratio of mass to molecular weight

So, 5 mL of ethanol =
`(3.945)/(46)mol` of ethanol = 0.086 mol of ethanol

Molarity represents number of moles of solute present in 1000 mL of solution.

Here solute is ethanol

So, molarity of ethanol in beer =
`(0.086* 1000)/(100)M=0.86M`