首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
混合法测定物质的比热容实验的方法:首先将被测物的质量进行测量,然后把被测物放入水中加热并测量其温度;测量量热器中水的质量,并测出其温度;再把高温被测物放进量热器中搅拌,测量出混合后的终温;然后根据比热容公式计算出被测物的比热容.然而学生实验中发现测量值始终小于理论值,这是由于整个实验过程损失了较多的热量.那么如何减小误差,本文对此提加以探讨.  相似文献   

2.
电热法测液体比热容实验的改进   总被引:2,自引:0,他引:2  
分析了电热法测液体比热容实验中误差的主要来源,介绍了一种适用于量热器系统,无论在密闭还是开放条件下,测量液体比热容的新方法。  相似文献   

3.
比热容作为重要的热力学参量,在生产实践中有着极其重要的作用.为解决精度低、耗费待测液体多、操作复杂等问题,在双量热器法的基础上,通过大量的实验探究,采用以水作为测量基准物质的水当量法并结合电压比较法,同时改进双量热器法和水当量法,综合两者优势所在,不仅提高测量精度,且简化实验操作,更易于指导生产实践.  相似文献   

4.
电热法测固体比热容实验的改进   总被引:2,自引:0,他引:2  
探讨了电热法测固体的比热容实验装置的改进,并介绍用自补偿方式消除系统误差的方法,用集成温度传感器AD590测量温度,通过模拟电路调零和放大,其温度由数字毫伏表直接显示,用不锈钢真空杜瓦瓶代替量热器。  相似文献   

5.
利用实验曲线计算液体比热容的方法   总被引:1,自引:0,他引:1  
电热法测液体比热容的实验中,由于量热器系统并非一个真实的绝热系统,在低于外界环境温度和高于外界环境温度时,量热器和外界环境之间存在不等的热量交换;同时由于量热器的散热系数是一未知的常数,对其散热不能进行修正,导致实验结果和标准值之间有较大的偏差.本文介绍的利用实验曲线计算液体比热容的方法,可以消除由于散热对实验的影响,得到比较准确的实验结果.一、计算原理由热力学第一定律可知,待测液体在外界环境温度T0附近在dt时间内所吸收的热量dQ应等于它从电热丝吸收的热量式中V、I分别为加热电阻丝两端的电压及其中的…  相似文献   

6.
液体比热容是反映液体特性的重要参量之一,是了解和利用液体的依据。纯净液体的比热容可通过查询获得,而混合溶液的比热容基本需要通过测量获得。本文利用水壶的保温特性,设计了一种可利用电加热法测量混合溶液等压比热容的系统,并通过分析实验中的温度变化获得了本测量系统的修正值,最后利用该系统测量了不同浓度盐溶液的等压比热容。  相似文献   

7.
对电流量热器法测定液体比热容实验的改进   总被引:1,自引:0,他引:1  
王文周 《物理实验》2001,21(8):38-39
考虑两个量热器的电阻不相等,推导出液体比热容的计算公式。不必交换电阻重测,按m2≈m1c1/c2称比较液体的质量,可以使两种液体的升温大致相等,散热条件基本相同。  相似文献   

8.
用电热法测固体比热容实验中虽然可以对初温和终温用作图法进行修正,但这种修正并不能从根本上解决量热器在升温过程中与周围环境之间的热交换问题,而且无法修正在实验过程中由于搅拌器的不断搅拌,增加了系统的机械能而引入的系统误差。我们对此实验作了改进,采用甲、  相似文献   

9.
兔主动脉比热容测量   总被引:2,自引:0,他引:2  
本文用差示扫描量热技术的分步扫描方法,测量了未加抗冻剂和加抗冻剂的兔主动脉在30-140℃温度范围内的比热容。实验发现相变过程中,未加抗冻剂的兔主动脉的最大表观比热容大于加抗冻剂的相应值;冻结状态相同温度下未加抗冻剂的兔主动脉的比热容小于的加抗冻剂的兔主动脉的比热容;溶解后的未加抗冻剂和加抗冻剂的兔主动脉的比热容随着温度的升高而减小。并将测量结果与其它方法获得的比热容数值进行了比较,发现实际测量的比热容值与估算之间还是有区别的。  相似文献   

10.
该实验利用测量气体比热容比的经典装置,证明小球装置中做简谐振动,并依据周期推导气体比热容比理论公式,分析了测定气体比热容比的误差来源采用计算机实时测量技术获得气体在任意时刻的压强,利用比热容比的相对不确定度确定了测量仪器,从而利用精确的测量量求得气体比热容比值,利用确定的仪器测量,最终实验相对百分误差控制在0.5%.  相似文献   

11.
This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO(s) have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO(s) relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.  相似文献   

12.
杨伟伟  邸友莹  孔玉霞  谭志诚 《中国物理 B》2010,19(6):60517-060517
This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K.A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method.Based on the fitted polynomial,the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K.The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter.The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion.The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.  相似文献   

13.
Crystal structure of n-undecylammonium bromide monohydrate was determined by X-ray crystallography. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 390?K. Two solid–solid phase transitions were observed for the title compound. The temperatures, molar enthalpies, and entropies of the phase transitions were derived based on the analysis of heat–capacity curve. Two polynomial equations of heat capacities as a function of temperature were fitted by least-squares method. Based on the two polynomial equations, smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15?K were calculated and tabulated at 5 K intervals.  相似文献   

14.
1-Decylammonium hydrochloride was synthesized by the method of liquid phase synthesis. Chemical analysis, elemental analysis, and X-ray single crystal diffraction techniques were applied to characterize its composition and structure. Low-temperature heat capacities of the compounds were measured with a precision automated adiabatic calorimeter over the temperature range from 78 to 380?K. Three solid–solid phase transitions have been observed at the peak temperatures of 307.52?±?0.13, 325.02?±?0.19, and 327.26?±?0.07?K. The molar enthalpies and entropies of three phase transitions were determined based on the analysis of heat capacity curves. Experimental molar heat capacities were fitted to two polynomial equations of the heat capacities as a function of temperature by least square method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15?K were calculated and tabulated at intervals of 5?K based on the fitted polynomials.  相似文献   

15.
Abstract

Isobaric heat capacities of liquid n-dodecane were measured at temperatures from 313.15 to 373.15 K and at pressures up to 100 MPa using a calorimetric device based on a Calvet calorimeter (Setaram (280). These experimental data were used to perform a comparative study in order to choose, from among the great number of equations of state proposed in the literature, the most appropriate to calculate the isobaric heat capacity.  相似文献   

16.
This paper reports that low-temperature heat capacities of 4-(2-aminoethyl)-phenol (C8H11NO) are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15K were calculated and tabulated at the interval of 5K. The energy equivalent, εcalor, of the oxygen-bomb combustion calorimeter has been determined from 0.68g of NIST 39i benzoic acid to be εcalor=(14674.69±17.49)J·K^-1. The constant-volume energy of combustion of the compound at T=298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ΔcU=-(32374.25±12.93)J·g^-1. The standard molar enthalpy of combustion for the compound was calculated to be ΔcHm = -(4445.47 ± 1.77) kJ·mol^-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ΔfHm(C8H11NO, s)=-(274.68 ±2.06) kJ·mol^-1, in accordance with Hess law.  相似文献   

17.
本文对热交换实验中量热器尺寸结构进行分析研究,阐述实验中量热器的最小热损耗只与其设计尺寸有关,而与其它实验值无关。  相似文献   

18.
本文以统计热力学中的BH微扰理论为基础,建立了一种推算实际气体比定容热容的方法。用这种方法对20余种实际气体在饱和线上和气相区的比定容热容进行了推算。计算结果表明,本文方法能推算普通气体、氟利昂类气体、烷烃类气体的比热容,在饱和线上推算的平均相对偏差为1.10%,过热区为1.46%,最大相对偏差不超过6%。  相似文献   

19.
A new crystalline complex(C8 H17 NH3) 2 CdCl 4(s)(abbreviated as C8Cd(s)) is synthesized by liquid phase reaction.The crystal structure and composition of the complex are determined by single crystal X-ray diffraction,chemical analysis,and elementary analysis.It is triclinic,the space group is P-1 and Z = 2.The lattice potential energy of the title complex is calculated to be U POT(C 8 Cd(s))=978.83 kJ·mol-1 from crystallographic data.Low-temperature heat capacities of the complex are measured by using a precision automatic adiabatic calorimeter over a temperature range from 78 K to 384 K.The temperature,molar enthalpy,and entropy of the phase transition for the complex are determined to be 307.3±0.15 K,10.15±0.23 kJ·mol-1,and 33.05±0.78 J·K-1 ·mol-1 respectively for the endothermic peak.Two polynomial equations of the heat capacities each as a function of temperature are fitted by using the leastsquare method.Smoothed heat capacity and thermodynamic functions of the complex are calculated based on the fitted polynomials.  相似文献   

20.
In this paper, we describe the operation of a vacuum adiabatic calorimeter controlled by a Rockwell AIM 65 microcomputer, which is suitable for specific heat measurements in the temperature interval 4.2–300 K. The system measures and calculates the specific heat and the results are printed out on a thermal tape. The cryostat, the electronic circuitry and the software are described. Results obtained using a pulsed heat technique on a specimen of high purity copper are given and compared with values reported in the literature.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号