Question

1. Calculate and describe how to prepare a 50.0 mL of 2.50x102 M solution of Morphine (C17H19NO3) write the procedure for preparing the solution: remember to note how many grams of your drug and how much water to add (hint: it is not 50mL of water)?

Answer 1

First calculate molar mass of Morphine

C₁₇H₁₉NO₃ = ( 17 $\times$ 12.01 ) + ( 19 $\times$ 1.0079 ) + 14.0067 + ( 3 $\times$ 16.00) = 285.33 g/mol

We know that, Molarity = No. of moles of solute / Volume of solution in L

$\therefore$ No. of moles of solute = Molarity $\times$ Volume of solution in L

$\therefore$ No. of moles of C₁₇H₁₉NO₃ = ( 2.50 $\times$ 10 ^-02 mol / L ) $\times$ 0.0500 L = 0.00125 mol

We have, No. of moles = Mass / Molar mass

$\therefore$ Mass = No. of moles $\times$ Molar mass

$\therefore$ Mass of C₁₇H₁₉NO₃ = 0.00125 mol $\times$ ( 285.33 g/mol ) = 0.3566 g = 0.357 g

Procedure : Weigh out accurately 0.357 g of Morphine. Transfer it carefully into 250 ml beaker. Dissolve in 20 ml of distilled water. Transfer carefully solution from beaker into 50.0 ml volumetric flask . Add distilled water up to the mark. Resultant solution will be 2.50 $\times$ 10 ^-02 mol / L morphine solution.