Question

E4B.13(a) Naphthalene, C, H, melts at 80.2°C. If the vapour pressure of liquid is 1.3 kPa at 85.8 °C and 5.3 kPa at 119.3°C, use the Clausius-Ch equation to calculate (i) the enthalpy of vaporization, (ii) the normal point, and (iii) the entropy of vaporization at the boiling point. lausius-Clapeyror (11) the normal boiling

Answer 1

i)

enthalpy for vaporization is calculated by using Clausius clapeyrons equation , and unit for Enathalpy will be = unit of gas constant X unit of temperature that is joules per Mole.

ii).

we know for any liquid the the vapour pressure at boiling point is always 1 atm. On conversion of atm into kilo pascal we know the relation

1 atm = 101.325 k Pa

hence T =? , P1 = 101.325 kPa and we take T2 and P2 feom any of given set. now again using Clausius clapeyrons equation we get the boiling point.

iii)

entropy of vaporization is related to enthalpy of vaporization at boiling point is H(vap)/T