My answer for this one is out by 8mg/100ml and I can\'t work out why. Can someon
ID: 1021454 • Letter: M
Question
My answer for this one is out by 8mg/100ml and I can't work out why. Can someone assist? Thankyou. The molecular weight of ethanol (C2H5OH) is 46.1 and the density of absolute (100%) ethanol = 0.79 g/mL. The legal limit for a driver’s blood alcohol is 50 mg of ethanol per 100 mL of blood (referred to as a blood alcohol content (BAC) of 0.05%). During a romantic candlelight dinner a 75kg person drinks a bottle (750 mL) of wine (14%) in the space of 3 hours. Ethanol is metabolized at a constant rate of 120 mg per hour per kg body weight, regardless of its concentration. •What is their blood alcohol content (mg/100 mL blood) at the end of the dinner? •How long will it take for their blood alcohol level to fall below the legal limit (0.05%) ?
Explanation / Answer
Molecular weight of ethanol (C2H5OH) is 46.1g (given)
Density of absolute (100%) ethanol = 0.79 g/mL. (given)
weight of person = 75 kg
volume of wine consumed = 750 mL
Percentage of ethanol in wine = 14%
Solution: 14% ethanol in wine means 14mL of ethanol in 100mL of wine. (Generally alcohal is present in V/V %)
Now 100 mL of wine contains ethanol = 14 mL
Then 750 mL of wine contains ethanol = (14/100)X750 mL
= 105 mL
Weight of ethanol consumed by person = volume X density
= 105X 0.79 g
= 82.95g = 82950 mg
An average person has total blood content = 6 liter = 6000mL
so blood alcohol content at the end of the dinner will be = (82950/6000)X100
= 1382.5mg/100mL of blood
Legal limit for blood alcohol = 50mg/100mL (given)
Required blood alcohol to be metabolized = 1382.5- 50 mg/100mL
= 1332.5mg/100mL
Since metabolism rate = 120mg/hour
time taken for blood alcohol to com legal limit = 1332.5/120 hour
= 11.1 hour
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