Calorimeter Bunsen ice

Dieterici s number is much higher than the others, which are in good agreement this experimenter used the Bunsen ice calorimeter, which is a very uncertain instrument. His results are, however, included in the mean adopted below. 

The Bunsen ice calorimeter measures AH at 273.15 K by melting ice in an ice-water mixture that is in contact with an Hg reservoir the partial conversion of some ice into water of higher density draws a weighable amount of Hg into the calorimeter. 

The high temperature enthalpies, 385.2 - 904.9 K, were measured by Kaylor (, 1, 1 ), using a Bunsen ice calorimeter and a CsCl sample of 99.8% purity. The heat capacities derived from the reported enthalpy data at temperatures 385.2 - 740.5 K appear too... 

McDonald et al. ( ) measured the high temperature enthalpies of ZrF (cr) at temperatures 283.9-1225.8 K in a copper block drop calorimeter. Smith et al. (4) used a Bunsen ice calorimeter for the enthalpy measurements in the temperature range 273-1150 K. These two sets of enthalpy data are not in good agreement. It is possible that the discrepancies are due to the difference in crystal structure of the samples used (see "Transition Data" for more information). In order to join smoothly with the low temperature heat capacities at 298.15 K, the high temperature heat capacities derived from the enthalpy data of McDonald et al. 

These data contain a broad lambda type transition with a heat capacity peak at 227.5 K. Powers and Blalock (9) measured high temperature enthalpy data for KOH(cr) in both the a and B phases in a Bunsen ice calorimeter. Their enthalpy data are scattered and not precise enough to accurately define the heat capacities for the a phase. Therefore, the selected heat capacities between 298 and 516 K are estimated by graphical extrapolation of the low temperature heat capacity data. Heat capacities for the B phase are from Powers and Blalock (9). 

Smith et al. [62SMI/M1L] used a Bunsen ice calorimeter to measure the high temperature heat content of Zr(S04)2(cr) from 273.15 to 1050 K. They found that the heat content could be described by the equation ... 

Isothermal which meant, for Swietoslawski, that the surrounding thermostat was kept at constant temperature. He included in this category the adiabatic systems in which the temperature of the thermostat, instead of being brought identical to that of the sample (to keep adiabatic conditions) was simply kept constant. He also included here phase-change calorimeters (the Bunsen ice calorimeter or the water vapour calorimeter successively described, in the same year 1887, by Joly and Bunsen). 

Isothermal calorimeters the thermal conductance is here very high. They consider that the most perfect example is the Bunsen ice calorimeter. They also quote the Junkers (flame) calorimeter with heat exchanger and water counter-current but consider that it is less perfect than the ice calorimeter and should rather be considered as semi-isothermal . 

The distinction between "Isothermal and "Conduction calorimeters, which they base on heat-conductance differences, does not withstand a close analysis. In a Bunsen ice calorimeter the temperature differences between the sample and the melting ice are of the same order of magnitude as in a conduction calorimeter, i.e. ranging from less than 10 K up to 1 K, depending on the rate of the reaction studied,the thermal conductivity of the sample, and the... 

Isothermal calorimeters, which make use of a phase change, the best example being the Bunsen ice calorimeter. 

Bunsen ice calorimeter by weighing the amount of molten water (Ginnings, Douglas, and Ball, 1950). The amount of methane burned for the measurement of its heat of combustion has been determined by direct weighing of a gas cylinder (Dale et al, 2002). 

The advantage of the Bunsen ice calorimeter over the corresponding device of Lavoisier and Laplace (1780) (see Section 1.1.1) lies in the fact that the only exchange of heat takes place with the ice jacket that envelops the sample container (almost) completely. Thus, there is no risk of any escape of heat by convection from the warmer ice water to the surroundings. This calorimeter is particularly suitable for the measurement of small quantities of slowly released heat. However, accurate measurements of small magnitudes of heat with a margin of uncertainty of about 0.5% or better can only be expected if a number of precautions are taken. Thus, the water and the ice in the vessel must be air free and very pure. The heat released by the sample must cause the formation of only a thin layer of water around the sample tube. Thick or overheated layers of water may cause the ice jacket to melt through or break apart. 

Bunsen Ice Calorimeter (measurement of the volume chanie on the mellini of ice)... 

Fig. 22. - Time-honored ice calorimeter, which was first intuitively used by Black and in the year 1780 improved by Lcn oisier and Laplace. The healed body is cooled down while placed in ice and the heat subtracted is proportional to the amount of melted water. In tlie year 1852, Bunsen proposed its more precise variant while determining volume instead of weight changes (middle). The cooling calorimeter was devised 1796 by Mayer. Dulong and Petit, but became known through the experiments by Regnault. Thcrmochamical measurements were furnished by Favre and Silberniann in 1852 usii the idea of Bunsen ice calorimeter but replacing ice by mercury the volume measurement of which was more sensitive. ...

Drop Calorimetry. In one type of drop calorimeter a sample at some elevated (or lower) temperature is dropped into a specimen receiver of known or calibrated thermal properties. By monitoring the temperature rise (or drop) of the specimen receiver, the heat capacity of the sample can be determined. A second type, known as the Bunsen ice calorimeter, uses the volume change of an ice-water mixture that results when heat is transferred from the sample to the mixture. 

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