Question
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 N2 = 28; R= 8.3 J mol–1 K–1.)
Solution
Mass of nitrogen, m = 2.0 × 10–2 kg = 20 g
Rise in temperature, ΔT = 45°C
Molecular mass of N2, M = 28
Universal gas constant, R = 8.3 J mol–1 K–1
Number of moles, n =
= (
)
= 0.714
Molar specific heat at constant pressure for nitrogen,
Cp =
R
=
× 8.3
= 29.05 J mol-1 K-1
The total amount of heat to be supplied is given by the relation,
ΔQ = nCP ΔT
= 0.714 × 29.05 × 45
= 933.38 J
Therefore, the amount of heat to be supplied is 933.38 J.
Rise in temperature, ΔT = 45°C
Molecular mass of N2, M = 28
Universal gas constant, R = 8.3 J mol–1 K–1
Number of moles, n =
= (
)= 0.714
Molar specific heat at constant pressure for nitrogen,
Cp =
R=
× 8.3 = 29.05 J mol-1 K-1
The total amount of heat to be supplied is given by the relation,
ΔQ = nCP ΔT
= 0.714 × 29.05 × 45
= 933.38 J
Therefore, the amount of heat to be supplied is 933.38 J.
