How much will the internal energy of nitrogen weighing 14 kg increase when its temperature rises by 20K.

To determine how much the internal energy ΔU of nitrogen with a mass of m = 14 kg increases with an increase in its temperature by ΔT = 20K, we use the formula: ΔU = (3/2) • ν • R • ΔT, where the universal gas constant R = 8.31 J / (mol • K), the number of moles of gas ν = m: M. We find the molar mass of gas M from the periodic table, taking into account that the nitrogen molecule includes two atoms: M = 2 • 0.0140067 = 0.0280134 (kg / mol) … Let us substitute the values ​​of physical quantities from the condition of the problem into the obtained formula and make calculations: ΔU = (3/2) • (14 kg: 0.0280134 kg / mol) • 8.31 J / (mol • K) • 20K; ΔU = 124650 J. Answer: the internal energy of nitrogen will increase by ΔU = 124650 J.