N calorimeter

There are two different kinds of calorimeter adiabatic (or quasi-adiabatic calorimeters) and non-isothermal, non-adiabatic calorimeters (often referred to as n-n calorimeters). The accuracy of measurements made using such methods will be high if ... 

A n-n calorimeter is schematically represented in Figure 4. In this system the thermal method of power estimation can be derived from Eqs. (9) and (10). Let T be the temperature of the jacket which will be kept constant Tx the actual temperature inside the calorimeter, 7 the measured temperature by the thermometer, k the... 

Figure 4. Schematic diagram of a nonisothermal nonadiabatic (n-n) calorimeter model.

If the transducer which has been tested with a calorimeter is used to sonicate another reactor, the calibration obtained with the calorimeter may give somewhat erroneous values of the delivered acoustic power. Separate calibrations should be made for each kind of condition thus the system should be considered as a n-n calorimeter and the methodology described above should be applied (i.e. the heat equivalent of the system should be determined together with a calculation of heat losses, or accurate independent calibration of the system with an electric heater). This approach can be very time consuming. 

When measurements in an open, flow n-n calorimeter are made after... 

From the methods in which the set of heat balance equations was used, the multidomains method ( 3.2.3) and the finite elements method ( 3.2.4) were elaborated. Numerical methods for the determination of thermokinetics in n-n calorimeters ( 3.2.11.1 - 3.2.11.6) were also developed. 

Let us normalize in the dimension of temperature the isoperibol n-n calorimeter characterized by a system of two concentric domains shown in Fig. 4.5 [21, 45]. 

For substances containing elements additional to C, H, O and N a rotating bomb calorimeter is generally used. A typical rotating bomb calorimeter system is shown in figure B 1.27.4. With tiiis calorimeter considerably more water is added to the combustion bomb and the continuous rotation of the bomb both about the cylindrical axis and end over... 

Albert H J and Archer D G 1994 Mass-flow isoperibole calorimeters Solution Calorimetry, Experimental Thermodynamics vol IV, ed K N Marsh and PAG O Hare (Oxford Blackwell)... 

Calit. a ceramic for insulators. T. N. Calorienwert, m. caloric value, calorimetrieren, v.t. measure with the calorimeter. 

The calculation takes more than one step, so we need to identify a process. Use Equation to find < calorimeter The heat gained by the calorimeter is supplied by the chemical reaction, so < calorimeter " calonmeter Because the calorimeter operates at constant volume, W = 0, so A " = ( reaction This energy change is for 0.1250 g of octane. Use n — mf M M to determine n, then use Equation to convert to the molar energy change A. S niolar = / n. A... 

Thermal Analysis - Differential Scanning Calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to characterize the thermal properties of the polymers synthesized. DSC analysis was performed on a Perkin-Elmer Differential Scanning Calorimeter, Model 2C with a thermal analysis data station. Thermal gravimetric analysis (TGA) was carried out on a DuPont thermal gravimeter, Model 951. From the DSC and TGA plots of poly (N-pheny 1-3,4-dimethylene-... 

Fig. 4. Vertical cross section of a high-temperature Calvet calorimeter (16) cell guides (A) thermal insulation (B) top (C) and bottom (N) electrical heaters thermostat consisting of several metal canisters (D, G, and H) switch (E) electrical heater (F) thermometers (I, J, and K) microcalorimetric element (L) and heat sink (M).

The relation between the emf of the thermoelectric pile and the heat flux from the calorimeter cell will be first established. Let us suppose (Fig. 8) that the process under investigation takes place in a calorimeter vessel (A), which is completely surrounded by n identical thermoelectric junctions, each separated from one another by equal intervals. The thermocouples are attached to the external surface of the calorimeter cell (A), which constitutes the internal boundary (Eint) of the pile and to the inside wall of the heat sink (B), constituting the external boundary (Eext) of the thermoelectric pile. The heat sink (B) is maintained at a constant temperature (6e). 

This simplified equation is equivalent to Tian s equation [Eq. (16)], and it appears that n is indeed the time constant r of the calorimeter. Thence, the successive coefficients n in Eq. (29) may be called the calorimeter time constants of 1st, 2nd,. .., ith order. When the Tian equation applies correctly, all time constants r, except the first r may be neglected. Since the value of the coefficients n of successive order decreases sharply [the following values, for instance, have been reported (40) n = 144 sec, r2 = 38.5 sec, r3 = 8.6 sec, ri 1 sec], this approximation is often valid, and the linear transformation of many thermal phenomena produced by the thermal lag in the calorimeter may actually be represented correctly by Eqs. (16) or (30). It has already been shown (Section IV.A) that the total heat produced in the calorimeter cell is then proportional to the area limited by the thermogram. 

From Tian s equation [Eq. (30)3, it appears that in order to transform the calorimeter response g(t) into a curve proportional to the thermal input f(t), it is sufficient to add, algebraically, to the ordinate of each point on the thermogram g(t), a correction term which is the product of the calorimeter time constant n, by the slope of the tangent to the thermogram at this particular point. This may be achieved manually by the geometrical construction presented on Fig. 10. 

The value of the calorimeter time constant r (= n), may be determined from the cooling curve which is recorded, for instance, when a Joule heating, which produced a constant deviation A0 of the base line (Fig. 11), is suddenly stopped (16). The comparison of Eqs. (14) and (15) shows that the cooling curve is represented by... 

The calculation of other bond enthalpy terms, such as E (Ge—Ge), E (Ge—O), E (Ge—N) and E(Ge—S), can be made from data in Table 1. However, due to the above-mentioned controversy involving most of the data obtained with static-bomb combustion calorimeters, we refrain from tabulating those terms. 

If the amount of compound burnt in the calorimeter is n, and remembering that no work is done, then a combination of Equations (3.7) and (3.8) suggests that the change in internal energy occurring during combustion is given by... 

The only studies on olefin polymerisations in methylene dichloride in which kp was deduced directly from the rate of reaction were carried out by Ledwith and his collaborators [9, 13] with extremely low concentrations of monomer and catalyst. They polymerised isobutyl vinyl ether and N-vinyl carbazole in a Biddulph-Plesch calorimeter with trityl or tropylium salts and obtained the first-order rate constants k1 from the conversion curves. Since different catalysts gave the same ratio of kx c they concluded that for each of them Xxr = c0 and hence identified with kp which must in fact be k p, as explained above. It seems unlikely that if several initiators give the same value of kp, they do so because they are all equally inefficient, and the inference that they do so because they are all 100% efficient, i.e., that for all of them x = c0, seems plausible - but it would be useful to have a direct check of this. 

In equations 7.27 and 7.28 m(BA), m(cot), m(crbl), and m(wr) are the masses of benzoic acid sample, cotton thread fuse, platinum crucible, and platinum fuse wire initially placed inside the bomb, respectively n(02) is the amount of substance of oxygen inside the bomb n(C02) is the amount of substance of carbon dioxide formed in the reaction Am(H20) is the difference between the mass of water initially present inside the calorimeter proper and that of the standard initial calorimetric system and cy (BA), cy(Pt),cy (cot), Cy(02), and Cy(C02)are the heat capacities at constant volume of benzoic acid, platinum, cotton, oxygen, and carbon dioxide, respectively. The terms e (H20) and f(sin) represent the effective heat capacities of the two-phase systems present inside the bomb in the initial state (liquid water+water vapor) and in the final state (final bomb solution + water vapor), respectively. In the case of the combustion of compounds containing the elements C, H, O, and N, at 298.15 K, these terms are given by [44]... 

The mean and standard deviation of the mean of the massic standard energy of combustion from the results in table 7.3 is Acm° (4-CNPyNO) = —25781.3 3.4 Jg-1. The corresponding standard molar energy of combustion is AcC/° (4-CNPyNO) = —3096.6 1.1 kJ mol -1, where the error quoted is twice the overall uncertainty (o-overaii), which includes contributions from the calibration of the calorimeter with benzoic acid and the combustion of n-hexadecane. The value of er0veraii is derived from [56,57] ... 

The energy equivalent of the calorimeter, e, and the enthalpy of the isothermal calorimetric process, A//icp, were derived from equations 8.2 and 8.4, respectively. The standard enthalpy of reaction 8.5 was computed as Ar//°(8.5) = AZ/icp/n, where n is the amount of substance of Mo(ri5-C5H5)2(C2H4) used in the experiment. The data in table 8.1 lead to a mean value Ar//°(8.5) = — 186.0 2.1 kJ mol-1, where the uncertainty is twice the standard deviation of the mean (section 2.6). This value was used to calculate the enthalpy of reaction (8.6), where all reactants and products are in their standard reference states, at 298.15 K, from... 

The experimental procedure was as described, the only difference being that a capillary containing a suitable amount of I2 was dropped into the reaction vessel (and the calorimeter allowed to stabilize) before the Cr(CO)6 sample was dropped. After recording the thermogram corresponding to reaction 9.15, the cell was removed and the contents analyzed to determine n (which varied from 0.30 to 0.38 in five separate experiments). 

E. S. Watson, M. J. O Neil, J. Justin,N. Brenner.X Differential Scanning Calorimeter for Quantitative Differential Thermal Analysis. Anal. Chem. 1964, 36, 1233-1238. 

B. Kasting for allowing his Calvet isothermal calorimeter to be used for some preliminary measurements and Dr. D. N. Rubingh for helpful discussions. 

The protein sample was then degassed under aspirator vacuum for a minimum of 20 min, with stirring, in order to remove excess dissolved gas forced into the solution during the diafiltration step. A sample of diafiltration buffer, to be used in filling the reference cell of the calorimeter, was given identical treatment. Buffers used were 50 mM acetate (pH 4.80), 43.4 mM 2-[N-morpholino]ethanesulfonic add (MES) (pH 6.32),... 

This is below the initial pressure in the calorimeter. The initial rate of pressure rise has therefore been taken (from measured data) as that corresponding to the relief pressure. This was 40 N/m2s. ... 

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