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 × 10⁻³ m aqueous solution required for the above dose.

Answer 1

Given, m = 1.5 × 10⁻³

The molar mass of nalorphene  (C₁₉H₂₁NO₃) is given as

19 × 12 + 21 × 1 + 1 × 14 + 3 × 16

= 311 g mol⁻¹

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

1 kg (1000 g) of water contains 1.5 × 10⁻³ mol = 1.5 × 10⁻³ × 311 g

= 0.467 g

= 467 mg

Therefore, total mass of the solution = (1000 + 0.467) g

= 1000.467 g

Thus, for 467 mg of nalorphene, the solution required = 1000.467 g

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

= `1000.467/467 xx 1.5`

= 3.21 g

Hence, the mass of the aqueous solution required is 3.21 g.