I got this question wrong, and I'm not sure where my mistakes lie. Can someone show me what I'm not doing right and what the correct answers should be?
"Some states have reduced the legal limit for alcohol sobriety from 0.10% to 0.080% alcohol by volume in blood plasma.
a) How many mL of alcohol are in 3.0 qt of blood plasma at the lower limit?
[my work]
x qt/3.0 qt= .080 %
x qt= .24
.24 qt x 1 L/1.057 qt x 1000 mL/1L= 230 mL
b)How many mL of alcohol are in 3.0 qt of blood plasma at the higher legal limit?
x qt/3.0 qt= .10
x qt= .30 qt
.30 qt x 1L/1.057 qt x 1000 mL/1 L= 280 mL
c) How much less alcohol is in 3.0 qt of blood plasma with the reduced sobriety level?
280 mL
- 230 mL
= 50 mL
I think your only error is that you didn't convert percent to a decimal.
0.08%v/v means 0.08 mL alcohol per 100 mL plasma. That is the equivalent of 0.8 mL per 1 L and you had
3 qt x (1 L/1.057 qt)= 2.838 L
Therefore, 2.838 L x 0.8 mL = 2.27 mL in the 3 qts. You can get the same number if you divided your 0.08% by 100 at the beginning and leave the remainder of your solution intact. I hope this helps. Thanks for showing your work.
oh, thank you. i realized after i typed it that something about the percent wasn't right. that clears it up a lot.
You must realize, also, that 0.080% and 0.10% have only two significant figures; therefore, the answer will have only two s.f.
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