__Question 12.2__:^{–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 mol

^{–1}K

^{–1}.)

__Solution__:*m*= 2.0 × 10

^{–2}kg = 20 g

Rise in temperature, Δ

*T*= 45°C

Molecular mass of N

_{2},

*M*= 28

Universal gas constant,

*R*= 8.3 J mol

^{–1}K

^{–1}

Number of moles, n = m/M

= (2 X 10

^{-2}X 10

^{3}) / 28

= 0.714

Molar specific heat at constant pressure for nitrogen, C

_{p}= (7/2)R

= (7/2) X 8.3

= 29.05 J mol

^{-1}K

^{-1}

The total amount of heat to be supplied is given by the relation:

ΔQ =

*nC*

_{P }Δ

*T*

= 0.714 × 29.05 × 45

= 933.38 J

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

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