L-deprenyl (C_13H_17NHCl) prevents the metabolism of dopamine in the brain. With
ID: 476814 • 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 1 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
a) concentration of L-deprenyl solution=10mg/10 ml of water
but 10ml of water=10ml*1gm/ml=10gm
so concentration of L-deprenyl solution=10mg/10 gm of water=10 mg/10*1000mg water=10 mg/10000 mg water
mass fraction of L-deprenyl=mass of L-deprenyl/total mass of solution=10/10+10000=10/10010=9.99*10^-4
b) molar mass of L-deprenyl=13* (atomic mass of carbon)+18*(mass o H atom)+1*(mass of N)+1*(mass of Cl)=13*12.01+18*1.008+14.007+35.5=223.781 g/mol
moles of L-deprenyl=mass in solution/molar mass=10 mg/223.781 g/mol=10*10^-3 g/223.781g/mol=0.045*10^-3 moles
moles of water=mass in solution/molar mass of water=10000mg/18g/mol=10g/18g/mol=0.55 moles
mole fraction of L-deprenyl=moles of L-deprenyl/total moles in solution=0.045*10^-3 /(0.045*10^-3 +0.55)=0.045*10^-3 /0.550045=8.18*10^-5
c.1 mole=6.022*10^23 molecules
So molecules of L-deprenyl=(6.022*10^23 molecules /mol)*(0.045*10^-3 moles)=0.271*10^20=2.71*10^19 molecules
d.Average MW=1/2(MW of L-deprenyl+MWof water)=0.5*(18.00+223.781)=120.890 g/mol
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