"To determine the amount of heroin in the mixture, you dissolve 1.00 g of the white powdery mixture in water in a 100.0-mL volumetric flask. You find that the solution has an osmotic pressure of 531 mm Hg at 25 °C. What is the composition of the mixture?"

Respuesta :

Explanation:

Formula to calculate osmotic pressure is as follows.

 Osmotic pressure = concentration × gas constant × temperature( in K)

Temperature = [tex]25^{o} C[/tex]

                      = (25 + 273) K

                      = 298.15 K  

Osmotic pressure = 531 mm Hg or 0.698 atm     (as 1 mm Hg = 0.00131)

Putting the given values into the above formula as follows.

       0.698 = [tex]C \times 0.082 \times 298.15 K [/tex]

               C = 0.0285

This also means that,

  [tex]\frac{\text{moles}}{\text{volume (in L)}}[/tex] = 0.0285

So,     moles = 0.0285 × volume (in L)

                      = 0.0285 × 0.100

                     = [tex]2.85 \times 10^{-3 }[/tex]

Now, let us assume that mass of [tex]C_{12}H_{23}O_{5}N[/tex] = x grams

And, mass of [tex]C_{12}H{22}O_{11}[/tex] = (1.00 - x)

So, moles of [tex]C_{12}H_{23}O_{5}N = \frac{mass}{\text{molar mass}}[/tex]

                              = [tex]\frac{x}{369}[/tex]

Now, moles of [tex]C_{12}H_{22}O_{11} = \frac{(1.00 - x)}{342}[/tex]

                   = [tex]\frac{x}{369} + \frac{(1.00 - x)}{342}[/tex]

                  = [tex]2.85 \times 10^{-3}[/tex]

             = x = 0.346

Therefore, we can conclude that amount of [tex]C_{12}H_{23}O_{5}N[/tex] present is 0.346 g  and amount of [tex]C_{12}H_{22}O_{11}[/tex] present is (1 - 0.346) g = 0.654 g.

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