Question

What amount of heat must be supplied to 2.0 x 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.)​

Answer 1

→ Mass of nitrogen,

→ m=2.0×10 −2 kg=20g

→ Rise in temperature, ΔT=45°C

→ Molecular mass of N2,M=28

→ Universal gas constant,

→ R=8.3J/molK

→ Number of moles, n=m/M

→ =(2×10 )−2 ×10 ( 3 ) / 28

→ =0.714

→ Molar specific heat at constant pressure for nitrogen,

→ Cp = (7/2)R

→ =(7/2)×8.3

→ =29.05Jmol −1 K −1

=29.05Jmol −1 K −1

→ The total amount of heat to be supplied is given by the relation: Q=nCPΔT

=0.714×29.05×45

=0.714×29.05×45=933.38J

→ Therefore, the amount of heat to be supplied is 933.38 J.

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