Question

Nalorphene (C19H21NO3), similar to morphine, is used to combat withdrawal symptoms in narcotic users. Dose of nalorphene generally given is 15 mg. Calculate the mass of 1.5 × 10-³ m aqueous solution required for the above dose.​

Answer 1

$\fbox{\texttt{\green{Answer:}}}$

Mass of water = 3.21 g

$\fbox{\texttt{\pink{Given:}}}$

Molality of the solution = $\bold{1.5\times{}10^{-3}}$

$\fbox{\texttt{\blue{To\:find:}}}$

Mass of solvent (water).

$\fbox{\texttt{\red{How\:to\:Find:}}}$

We know,

$\bold{Molality=\frac{Moles\:of\:solute}{Mass\:of\:solvent\:(in\:g)}\times{}1000}$

Molecular mass of nalorphene = 19 × 12 + 21 × 1 + 1 × 14 + 3 × 16 = 311 g

Moles of nalorphene (solute) =

$\bold{\frac{1.5\times{}10^{-3}}{311}=4.82\times{}10^{-6}\:mol}$

$\rule{200}2$

Applying the formula for molality,

$\implies\bold{1.5\times{}10^{-3}=\frac{4.82\times{}10^{-6}}{Mass\:of\:water}\times{}1000}$

$\implies\bold{Mass\:of\:water=\frac{4.82\times{}10^{-6}\times{}1000}{1.5\times{}10^{-3}}}$

$\implies\bold{3.21\:g}$