The Molar heat capacities of nitrogen at constant pressure and constant volume are 29.11kJ/k mole
K and 20.81 kmole K, respectively. When 5 gram of nitrogen is heated from 290 to 310 KD)
the decrease in its internal energy and in the external work done are, (Molecular weight of
1) 74.32 1,29641
2) 29.64 ], 74.32J
3) 64.32 J, 19. 64 )
4) 94,32 J 39.64.
Answers
Given: C(p) = 29.11 kJ / k mole K, C(v) = 20.81 kJ / k mole K , m 5 x 10^-3 kg, T1 = 290 K, T2 = 310 K, Molecular weight (m) = 28
To find: The decrease in its internal energy and in the external work done are?
Solution:
- Now, the difference between the given temperatures are:
ΔT1 = T2 - T1
= 310 - 290
= 20 K
- So now, we know the formula for change in internal energy
(dU) = (m/M) x C(v) x d x T
- Putting the values in the formula we get:
(dU) = (5 x 10^-3 / 28) x 20.81 x 10³ x 20
= 74.32 J
- Now, we also know the formula for external work done
(dW) = dQ – dU
- Putting the values in the formula we get:
(m/M) x C(v) x d x T - d(U)
= (5 x 10^-3 / 28) x 20.81 x 10³ x 20 - 74.32
= 103.96 - 74.32
= 29.64 J
Answer:
The decrease in its internal energy is 74.32 J and in the external work done is 29.64 J