Question

The amount of heat supplied to 4 × 10–2 kg of nitrogen at room temperature to rise its temperature by 50° C at constant pressure is (Molecular mass of nitrogen is 28 and R = 8.3 J mol–1 K–1)

• A. 2.08 Kj
• B. 3.08 kJ
• C. 4.08 kJ
• D. 65.37 J

Answer 1

Answer: (A)

2.08 Kj

Answer 2

: Given

$m = 4 \times 10 ^ { - 2 } \mathrm {~kg} = 40 \mathrm {~g} , \Delta T = 50 ^ { \circ } \mathrm { C }$

Number of moles, $n = \frac { m } { M } = \frac { 40 } { 28 } = 1.43$

As nitrogen is a diatomic gas, molar specific heat at constant pressure is

As $\Delta Q = n C _ { p } \Delta T$ $\therefore \Delta Q = 1.43 \times 29.05 \times 50$ $= 2.08 \times 10 ^ { 3 } J = 2.08 \mathrm {~kJ}$