Question

It takes 330 joules of energy to raise the temperature of 24.6 gbenzene from 21 degrees Celsius to 28.7 degrees Celsius at constantpressure. What is the molar hear capacity of benzene at constantpressure?

Answer 1

Given :

Energy , E = 330 J .

Initial temperature , $T_i=21^oC$ .

Final temperature , $T_f=24.6^oC$ .

Mass of benzene , m = 24.6 g .

To Find :

The molar hear capacity of benzene at constant pressure .

Solution :

Molecular mass of benzene , M = 78 g/mol .

Number of moles of benzene :

$n=\dfrac{24.6}{78} \ mol\\\\n=0.32 \ mol$

Energy required is given by :

$q=nC_p\Delta T\\\\330=0.32\times C_p\times (28.7-21)\\\\C_p=\dfrac{330}{0.32\times 7.7}\ J\ mol^{-1}^oC^{-1} \\\\C_p=133.9\ J\ mol^{-1}^oC^{-1}$

Hence , this is the required solution .