Question

The nonvolatile, nonelectrolyte DDT , C14H9Cl5 (354.5 g/mol), is soluble in benzene, C6H6. Calculate the osmotic pressure (in atm) generated when 13.6 grams of DDT are dissolved in 251 mL of a benzene solution at 298 K. atm

Answer 1

Step 1

The osmotic pressure is calculated as follows:

$\begin{gathered} \pi\text{ = C x R x T} \\ C\text{ = molarity = }\frac{moles\text{ of solute}}{Volume\text{ of solution \lparen L\rparen}} \\ R\text{ = 0.082 }\frac{atmxL}{mol\text{ x K}} \end{gathered}$

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Step 2

Information provided:

The mass of solute = 13.6 g

Volume of solution = 251 mL

Absolute temperature = T = 298 K

The molar mass of solute = M = 354.5 g/mol

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Step 3

Procedure:

1 L = 1000 mL => Volume = 251 mL x (1 L/1000 mL) = 0.251 L

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C = moles of solute/volume of solution (L)

C = mass of solute/(molar mass x Volume (L))

C = 13.6 g/(354.5 g/mol x 0.251 L)

C = 0.153 mol/L

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π = C x R x T

π = 0.153 mol/L x 0.082 atm L/mol K x 298 K

π = 3.74 atm

Answer: π = 3.74 atm