Question

Question 2.29

Nalorphene $\left(C_{19}{H}_{21}N{O}_3\right)$, similar to morphine, is used combat withdrawal symptoms in narcotic users. Does of nalorphene generally given is 1.5 mg. Calculate the mass of $1.5\times {10}^{-3}m$ aqueous solution required for the above dose.

Answer 1

$m=1.5\times {10}^{-3}mor1.5\times {10}^{-3}molk{g}^{-1}$

Mass of solute $=1.5\times {10}^{-3}g$ or 1.5 mg

Mass of solvent=?

Molar mass of solute

$\left(C_{19}{H}_{21}N{O}_3\right)=(12\times 19)+(1\times 21)+\left(14\right)+(16\times 3)$

$=311gmo{l}^{-1}$

Number of moles of solute $=\frac{Mass}{Molarmass}=\frac{(1.5\times {10}^{-3}g)}{\left(311gmo{l}^{-1}\right)}$

Molality (m) $=\frac{Numberofmoles}{Massofsolventinkg}$

Mass of solvent $=\frac{Numberofmoles}{Molality}$

$=\frac{(1.5\times {10}^{-3}g)}{\left(311gmo{l}^{-1}\right)}\times \frac{1}{(1.5\times {10}^{-3}molkgg)}$

$=\frac{1}{311}=0.0032kg$ or 3.2g