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 x 10-3 m aqueous solution required for the above dose.
The molar mass of nalorphene (C19H21NO3) is given as:
19 x 12 + 21 x 1 + 1 x 14 + 3 x 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 x 10-3 x 311 g
= 0.4665 g
Therefore, total mass of the solution = (1000 + 0.4665)g
= 1000.4665 g
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
= \(\frac{1000.4665 \times 1.5 \times 10^{-3}}{0.4665}\)g
= 3.22 g
Hence, the mass of aqueous solution required is 3.22 g.