A stream of hot gases at \(1,000^{\circ} \mathrm{C}\), having a specific heat of \(6.9 \mathrm{cal} / \mathrm{mol}-{ }^{\circ} \mathrm{C}\), is used to preheat air fed to a furnace. Because of insufficient insulation, the hot gas cools to \(700^{\circ} \mathrm{C}\) before it enters the air preheater. How much availability per mole does it lose?