Nalorphene `(C_(19)H_(22)NO_(3))`, similar to morphine , is used to combat withdrawal symptoms in narcotic users. The dose of nalorphene generally given is `1.5 mg`. Calculate the mass of solution of `1.5xx10^(-3)m` aqueous solution required for the above dose.

Explanation

Molality ` = ("Moles of solute")/("Mass of solvebt (in g)") xx 1000`
Molecular mass of nalorphene
` = 19 xx 12 + 21 xx 1 + 1 xx 14 + 3 xx 16`
`= 311`
Moles of nalorphene `= (1.5 xx 10^(-6))/(311) = 4.82 xx 10^(-6)` mol
`1.5 xx 10^(-3) = (4.82 xx 10^(-6)xx 1000)/(1.5 xx 10^(-3)) `
`therefore` Mass of water `= (4.82 xx 10^(-6) xx 1000)/(1.5 xx 10^(-3))`
` = 3.21` g