Question

Nalorphene (C₁₉H₂₁NO₃), 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 × 10⁻³m aqueous solution required for the above dose.

Answer 1

The molar mass of nalorphene is given as:

In 1.5 × 10⁻³m aqueous solution of nalorphene,

1 kg (1000 g) of water contains 1.5 × 10⁻³ mol

Therefore, total mass of the solution

This implies that the mass of the solution containing 0.4665 g of nalorphene is 1000.4665 g.

Therefore, mass of the solution containing 1.5 mg of nalorphene is:

Hence, the mass of aqueous solution required is 3.22 g.

Note: There is a slight variation in this answer and the one given in the NCERT textbook.