配位化合物Zn(Met)_3(NO_3)_2·H_2O(s)(Met=L-α-蛋氨酸)的低温热容及标准摩尔生成焓(英文)

Low Temperature Heat Capacities and Standard Molar Enthalpy of Formation of the Coordination Compound Zn(Met)_3(NO_3)_2·H_2O(s)(Met=L-α-Methionine)

利用精密绝热热量仪测定了配合化合物Zn(Met)_3(NO_3)_2·H_2O(s)(Met=L-α-蛋氨酸)在78-371 K温区的摩尔热容.通过热容曲线解析,得到了该配合物的起始脱水温度为T_D=325.10 K.将该温区的摩尔热容实验值用最小二乘法拟合得到了摩尔热容(C_p)对约化温度(T)的多项式方程,由此计算得到了配合物的舒平热容值和热力学函数值.基于设计的热化学循环,选择100 mL 2 mol·L^(-1)HCl溶液为量热溶剂,利用等温环境溶解-反应热量计,得到了298.15 K配合物的标准摩尔生成焓Δ_f H_m^0[Zn(Met)_3(NO_3)_2·H_2O,s]=-(1472.65±0.76)J·mol^(-1).

Low temperature heat capacities of the compound Zn（Met）3（NO3）2 .H2O（s） have been measured by a precision automated adiabatic calorimeter over the temperature range 78-371 K. The initial dehydration temperature of the coordination compound was determined to be TD=325,10 K by analysis of the heat-capacity curve. The experimental values of the molar heat capacities in the temperature region have been fitted to a polynomial equation of heat capacities with the reduced temperature （X）, [X= f（T）], by the least squares method. Smoothed heat capacities and thermodynamic functions relative to the standard reference temperature 298.15 K of the compound were derived from the fitted polynomial equation and listed at 5 K internals. Using 100 mL of 2 mol. L-1 HCl（aq） as calorimetric solvent, with an isoperibol solution-reaction calorimeter, the standard molar enthalpy of formation of the compound was determined to be △fH0m[Zn（Met）3（NO3）2·H2O,s]=-（1472.6±0.76）J.mol-1 by a designed thermochemical cycle.