1 mol单原子理想气体从400 K经历（1）恒压膨胀，（2）绝热膨胀，到达相同的末态温度300 K，两过程热力学能变和焓的变化分别为: triangle U1= ( ) kJ, triangle H1= ( ) kJ; triangle U2= ( ) kJ, triangle H2= ( ) kJ。（保留四位小数）

根据理想气体性质，ΔU和ΔH仅与温度变化有关： \[ \Delta U = nC_V \Delta T = \frac{3}{2}R (T_2 - T_1) = \frac{3}{2} \times 8.314 \times (-100) = -1247.1 \, \text{J/mol} = -1.2471 \, \text{kJ/mol} \] \[ \Delta H = nC_P \Delta T = \frac{5}{2}R (T_2 - T_1) = \frac{5}{2} \times 8.314 \times (-100) = -2078.5 \, \text{J/mol} = -2.0785 \, \text{kJ/mol} \] 无论过程如何，ΔU和ΔH均相同。 答案： \[ \Delta U_1 = \Delta U_2 = -1.2471 \, \text{kJ}, \quad \Delta H_1 = \Delta H_2 = -2.0785 \, \text{kJ} \]