A heat engine is operating in between 500 K and 400 K. If the engine absorbs 100 J heat per cycle, t — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

Carnot efficiency is the absolute maximum: $\eta = 1 - 400/500 = 0.2$. Maximum work is $0.2 \times 100 = 20\text{ J}$. Minimum possible heat rejected $Q_C = 100 - 20 = 80\text{ J}$. Therefore, any heat rejection below 80 J (such as 70 J or 75 J) violates the Second Law.