Browse Questions

# Nalorphene $(C_{19}H_{21}NO_3)$, similar to morphine, is used to combat withdrawal symptoms in narcotic users. Dose 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.

$\begin{array}{1 1}3.21g\\4.21g\\3.51g\\2.21g\end{array}$

$1.5\times 10^{-3}m$ solution means that $1.5\times 10^{-3}$ mole of nalorphene is dissolved in 1 kg of water.
Molar mass of $C_{19}H_{21}NO_3=19\times 12+21+14+48$
$\Rightarrow 311gmol^{-1}$
$\therefore 1.5\times 10^{-3}$ mole of nalorphene =$1.5\times 10^{-3}\times 311g$
$\Rightarrow 0.467g$
$\Rightarrow 467mg$
Mass of solution =$1000g +0.467g$
$\qquad\qquad\quad\;\;=1000.467g$
Thus,for 467 mg of nalorphene solution required 1000.467 for 1.5mg nalorphene=$\large\frac{1000.467\times 1.5}{467}$
$\Rightarrow 3.21g$