Thermodynamics
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Question : 2
Total: 10
What amount of heat must be supplied to 2.0 × 10 – 2 kg of nitrogen (at room temperature) to raise its temperature by 45°C at constant pressure? (Molecular mass of N 2 = 28 ; R = 8.3 J m o l – 1 K – 1 . )
Solution:
Mass of nitrogen gas, m = 2 × 10 − 2 k g = 20 g
Molecular mass of nitrogen gas= 28 g
Rise in temperature,Δ T = 45 ° C
Heat supplied = ?
Number of molesn =
=
=
For nitrogen( N 2 ) which is a diatomic gas, molar specific heat at constant pressure
C p =
R where R = 8.3 J m o l − 1 K − 1
Therefore, heat supplied to the gas
Δ Q = n C p Δ T
=
×
× R × 45
=
×
× 8.3 × 45
= 933.8 J ≈ 934 J
Molecular mass of nitrogen gas
Rise in temperature,
Heat supplied = ?
Number of moles
For nitrogen
Therefore, heat supplied to the gas
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