L-deprenyl (C_13H_17NHCl) prevents the metabolism of dopamine in the brain. With
ID: 476676 • Letter: L
Question
L-deprenyl (C_13H_17NHCl) prevents the metabolism of dopamine in the brain. With increased dopamine availability in the brain, the symptoms of Parkinson's disease may subside. Assume a dose of L-deprenyl of 140 (microgram/day.kg patient weight) for treating Parkinson's patients. In one preparation. 10 mg of L-deprenyl is dissolved in 10 mL water. Assume water density to be I gm/mL. Calculate the following mass fraction of L-deprenyl the mole fraction of L-deprenyl. Number of molecules of L-deprenyl The average MW of the solution.Explanation / Answer
given
10 mg of L- deprenyl is dissolved in 10 mL of water and denstiy of water = 1 gm/mL = 1000 mg/mL
weight of water = V * density = 10 mL * 1000 mg/mL =10000 mg of water
so 10 mg of L- deprenyl is dissolved in 10000mg of water
mass fraction = mass of L-deprenyl / mass of solution = 10 mg / (10000 + 10 ) mg = 9.99 * 10-4 Answer (a)
(b) no of moles of L-deprenyl = mass of L-deprenyl / Mol. wt of L-deprenyl =10*10-3 g/ 187.281 g /mol
= 5.34*10-5 moles
no of moles of water = mass of water / mol. wt of water = 10 g / 18 g/ mol =0.55 moles
mole fraction of L-deprenyl = moles of L-deprenyl / total no of moles = 5.34*10-5 moles /(5.34*10-5 + 0.55)
mole fraction of L-deprenyl = 9.708 * 10-5 (x1) Answer (b)
mole fraction of L-deprenyl = 1- 9.708 * 10-5 = 0.9999 (x2)
(c) Number of molecules of L-deprenyl = no of moles * avagadro number = 5.34*10-5 / 6.023*1023
Number of molecules of L-deprenyl = 8.86* 1017 molecules Answer (c)
(d) Average MW of solution = x1 * M.W1 + x2 * M.W2 = 9.708 * 10-5 * 187.281 + 0.9999* 18.02 = 18.04 Answer (d)
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