# help!Watch

#1
hi, this is a bit past a-levels chemistry statistics, but i was wonering if anyone knows how to work this out: would really appreciate it!

Blood alcohol concentration (BAC) is sometimes measured as a percentage by
volume. In many countries it is illegal to drive with a BAC of greater than 0.08%. A
BAC of 0.45% is generally considered fatal. How much alcohol (in millilitres) would
be present in the blood of an average person at (i) the legal limit for driving and (ii)
the generally accepted fatal dose (assume an average blood volume of 5 litre)? (3
marks)
0
12 years ago
#2
(i) 1 litre = 1000 ml, so 5 litres = 5000 ml. Hence, the answer is ml. (Basically: turn the percentage into a decimal by dividing by 100, and then multiply this by 5000.)

Can you now work out (ii)? (It's the same idea.)

0
#3
Oh how easy i thought it would be something much more complicated! lol

1)A blood sample was analysed for plasma insulin (MW = 5807.67) and glucose (MW =180.6) concentrations and the results presented as follows:Insulin = 0.75 ng ml(-1) ; glucose = 0.62mg l (-1) Express these values as molar concentrations using a suitable prefix (pico, micro etc)

2)A biotech company has designed a new drug-delivery system, in which drugs are released slowly from hollow microspheres. Each microsphere has an internal diameter of 45 um (micro meters) and is filled with the drug solution. How many microspheres would have to be injected to deliver 15 ul (micro litres)

God bless anyone that manages to help me!!
0
12 years ago
#4
o wow these q's are hard but ive just done my alevels so prob thats why lol.
0
12 years ago
#5
(Original post by Kurdi_princess)
Oh how easy i thought it would be something much more complicated! lol

1)A blood sample was analysed for plasma insulin (MW = 5807.67) and glucose (MW =180.6) concentrations and the results presented as follows:Insulin = 0.75 ng ml(-1) ; glucose = 0.62mg l (-1) Express these values as molar concentrations using a suitable prefix (pico, micro etc)
1)

Insulin conc = 0.75 ng/mL
= 0.75 picograms/L

(Next convert grams/L into moles/L)

Moles = Mass x Molecular Weight
= 0.75 x 10^-12 x 5807.67
= 4.3575... x 10^-9 moles/L

You should be able to do the same with glucose
0
12 years ago
#6
(Original post by Kurdi_princess)
2)A biotech company has designed a new drug-delivery system, in which drugs are released slowly from hollow microspheres. Each microsphere has an internal diameter of 45 um (micro meters) and is filled with the drug solution. How many microspheres would have to be injected to deliver 15 ul (micro litres)
2) Volume of sphere fomula:

Radius = 45/2 = 22.5 micrometers

Volume of 1 microsphere = 4/3 x 'pi' x (22.5 x 10^-6)^3
= 4.7712... x 10^-14 litres

Number of microspheres = Dose needed / Volume of 1 microsphere
= 15 x 10^-6 / 4.7712... x 10^-14
= 3.1438 x 10^8 microspheres

0
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