Final answer:
It typically takes about 2.5 hours for the body to metabolize the alcohol from 12 ounces of beer, but this can vary between individuals. The metabolism rate is constant and dependent on liver enzymes, not on the amount of alcohol consumed.
Step-by-step explanation:
On average, it takes about 2.5 hours for the body to remove the alcohol contained in 12 ounces of beer. This process involves a series of metabolic reactions primarily in the liver, where ethanol concentration decreases at a constant rate until it reaches zero. However, individual variation exists, generally ranging between 25-30%, influenced by factors such as body size and the amount of the enzyme alcohol dehydrogenase present in the liver. Also, women metabolize alcohol a bit more slowly than men.
Additionally, the rate at which the body can process alcohol does not increase with greater quantities consumed; it is dependent on the liver's enzymatic capacity. The rate of ethanol metabolism is about 15 mg/dL per hour, but this rate can change during periods of heavy drinking, where the microsomal ethanol oxidizing system (MEOS) may metabolize most of the excess ethanol ingested.