Big Murph Pale Ale

murphale.jpg

We bottled the Murph yesterday. Gregg came with us to check out the joint, and lend a hand on the assembly line (photo). It took us 2 hours to wait, wash and bottle 4 cases of beer. Compared to the other bottlers, I think it’s safe to say we were a model of efficiency.

According to the worksheet supplied by the brewers, the original specific gravity (OG) of our concoction was 1.078, and the final specific gravity (FG) was 1.014. On the sheet, they wrote that it is 6.2% alcohol by weight, and 7.93% alcohol by volume. Following the instructions at howstuffworks.com:

Starting gravity – final gravity = mass of CO2 gone from fermenting

1.078 – 1.014 = 0.064

Multiply by 1.05 (mass ratio of CO2 to ethyl alcohol) = mass of alcohol per liter

0.064 x 1.05 = 0.0672

Mass per liter divided by final specific gravity = % alc. by mass

0.0672 / 1.014 = 0.0663, or 6.63% alc. by mass (misnomered “alcohol by weight” or ABW)

ABW divided by density of ethyl alcohol (which is 0.79 kg/L) = alc. by volume

0.0663 / 0.79 = 0.0839, or 8.4% alc. by volume

I wonder why the discrepancy in the worksheet provided by the brewer exists?

As for the beer itself, it’s kind of sweet, medium hoppiness with only a hint of bitter. I think it’s pretty good, but I’d like to hear what Gregg thinks of the stuff.

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