4) The density of a sample of PMMA is 1.18 g/cm3. Estimate the enthalpy change involved in dissolving 1.0g of PMMAin 50 cm3 of benzene at 20°C. What assumptions have you made in obtaining your answer? (σbenzene = 9.15 (cal/cm3)1/2 , σPMMA = 9.09 (cal/cm3)1/2
The equation which will be useful to calculate the enthalpy change is
Where Solubility parameter
H = enthalpy, here it is the heat of vaporization
T = temperature
Vm = molar volume
R = universal gas constant
Now, assuming that the polymer, PMMA, will be complete miscible in benzene, we can find the value of H for each component.
For PMMA
C
R = 8.134 X 107 egr K-1 mol-1
********************* (1)
For Benzene
Vm = 50 cm3
Hence
*************************** (2)
Now (2) - (1)
4) The density of a sample of PMMA is 1.18 g/cm3. Estimate the enthalpy change involved...
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