Question

What is the change in the standard molar entropy of sulphur trioxide gas SO3 when it is cooled from a temperature of 90degree C to 20degree C at a constant pressure of 1 bar? The standard molar constant-pressure heat capacity of sulphur trioxide

Answer 1

Given:

The sulphur trioxide gas SO3 is cooled from a temperature of 90degree C to 20degree C at a constant pressure of 1 bar? The standard molar constant-pressure heat capacity of sulphur trioxide

To find:

What is the change in the standard molar entropy of sulphur trioxide gas SO3?

Solution:

From given, we have,

The sulphur trioxide gas SO3 is cooled from a temperature of 90degree C to 20degree C at a constant pressure of 1 bar

we know that the specific heat capacity of sulphur trioxide is 0.77 ca/g/°C = 3223.836 J/kg/K.

we use the formula,

ΔS = Cp ln (T2/T1)

we have,

Cp = 3223.836 J/kg/K.

T2 = 273 + 20 = 293 K

T1 = 273 + 90 = 363 K

so, we get,

ΔS =  3223.836  ln (293/363)

ΔS =  3223.836  × -0.2144

∴ ΔS = - 690.64 kJ/K.

Therefore, the change in the standard molar entropy of sulphur trioxide gas SO3 is 690.64 kJ/K.