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).1

Answer 1

Answer:

$0.86M$

Explanation:

Hello,

In this case, one must consider that the ethanol's concentration in beer is defined as:

$\% et =\frac{m_{et}}{m_{beer}}$

In such a way, since molarity is defined as:

$M=\frac{mol_{et}}{Volume_{solution}}$

One is asked to compute the moles, considering a basis of 5 milliliters of ethanol and 100 milliliters of beer, thus:

$mol_{et}=5mL*\frac{0.789g}{1mL} *\frac{1mol}{46g}=0.086mol\ et$

Now, the volume in molarity is required in liters, therefore:

$Volume_{beer}=100mL*\frac{1L}{1000mL}=0.1L$

Therefore, the molarity turns out:

$M=\frac{0.086mol}{0.1L}=0.86M$

Best regards.