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

${ \tt{ \underline{ \underline{Question :-}}}}$

→ 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.)

${\tt {\underline {\underline{Answer :-}}}}$

Mass of nitrogen ( m ) = 2 x 10 ^ -2 Kg

Increase in temperature ( AT ) = 45 ° C

Molecular mass of N2 ( M ) = 28 g

= 28 x 10 ^ -3 Kg

R = 8.3 J / mol.K

Number of moles ( n ) = m / M

= 2 x 10 ^ -2 / 28 x 10 ^ -3

= 5/7

Molar specific heat at constant pressure ( Cp )

= YR / ( Y - 1 ) where Y is atomicity of gases .

Y = 1.4 Cp = 1.4R / ( 1.4-1 )

= 7R / 2

So , heat supplied = nCpAT

= 5/7 x 7/2 x 45 x 8.3

= 933.75 J -

Answer 2

Given molecular mass of nitrogen is 28 and R=8.3Jmole-1K-1.

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