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.

Options

A. `3.2xx10^(-2)kg`
B. `3.2xx10^(-4)kg`
C. `3.2xx10^(-3)kg`
D. `3.2xx10^(-5)kg`

Answer

C

Explanation

`m=1.5xx10^(-3)mor1.5xx10^(-3)" mol " kg^(-1)`
`"Mass of solute"=1.5xx10^(-3)gor1.5mg`
Mass of solvent= ?
Molar mass of solute
`(C_(19)H_(21)NO_(3))=(12xx19)+(1xx21)+(14)+(16xx3)`
`=311g" mol"^(-1)`
`"Number of moles of solute"=("Mass")/("Molar mass")`
`=((1.5xx10^(-3)g))/((311g" mol"^(-1)))`
`"Molarity(m)"=("Number of moles")/("Mass of solvent in kg")`
`"Mass of solvent"=("Number of moles")/("Molarity")`
`=(1.5xx10^(-3))/((311g" mol"^(_1)))xx(1)/(1.5xx10^(-3)" mol kg")`
`=(1)/(311)=0.0032" kg or "3.2g`