If 21 textJ of heat energy is supplied to an ideal diatomic gas at constant pressure, then the change in its internal energy is

Question

If 21 textJ of heat energy is supplied to an ideal diatomic gas at constant pressure, then the change in its internal energy is (A) 10J (B) 12J (C) 15 J (D) 18J

Tardigrade Admin · Accepted Answer

Q=nCpΔ T ⇒ 21=n(7/2)RΔ T ⇒ nRΔ T=6 Δ U=(5/2)nRΔ T Δ U=(5/2)× 6=15J

Q. If $21 J$ of heat energy is supplied to an ideal diatomic gas at constant pressure, then the change in its internal energy is

$10 J$

$12 J$

$15 J$

$18 J$

$Q = n C_{p} Δ T$
$\Rightarrow 21 = n \frac{7}{2} R Δ T$
$\Rightarrow n R Δ T = 6$
$Δ U = \frac{5}{2} n R Δ T$
$Δ U = \frac{5}{2} \times 6 = 15 J$

Q. If 21J of heat energy is supplied to an ideal diatomic gas at constant pressure, then the change in its internal energy is

10J

12J

15J

18J