Question

The heat energy in joules must be supplied to
14gms of nitrogen at room temperature to
rise its temperature by 40°C at constant
pressure is (Mol.wt.of N, =28gm, R=universal
gas constant)
1) 50R 2) 60R 3) 70R 4) 80R​

Answer 1

Given :

• m = 14g
• ∆ T = 40°C
• M = 28

Solution :

Number of moles

$\bf n = \frac{m}{M} = \frac{ 14}{28} = 0.5$

Molar specific heat at constant pressure for nitrogen

$\bf C_p = \frac{7}{2} r$

The total amount of heat to be supplied is given by the relation:

$\bfΔQ=n C_p ΔT \\ \\ \bf 0.5× \frac{ 7}{7}R×40=70R$