Some thermodynamic properties of n-heptane on the saturation line

Zotov, V. V.; Neruchev, Yu. A.; Otpushchennikov, N. F.

doi:10.1007/bf00830017

Cited by 5 publications

(8 citation statements)

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“…Moreover, their concave directions as functions of the temperature are opposite and compensate each other. As a result, their common influence is comparable with the experimental errors and one can consider in practice the measured heat capacity с as с p (practically coinciding with с σ there) before the jump and с v – after, considering the latter as connected to the isobaric heat capacity via the standard thermodynamic formula 20

c_{p} - c_{v} = - T \frac{{([], {((), \frac{\partial V}{\partial T})}_{p})}^{2}}{{((), \frac{\partial P}{\partial V})}_{T}},

where one can use reference data on the density and the isobaric compressibility given by Zotov et al 19 to calculate respective derivatives connected to the isobaric expansion coefficient and the isothermal bulk modulus.

α_{p} = \frac{1}{V} {(\frac{\partial V}{\partial T})}_{p} and κ_{T}^{- 1} = - V {(\frac{\partial P}{\partial V})}_{T}

…”

Section: Resultsmentioning

confidence: 90%

“…Figure 1 represents the results of measurements for n‐heptane corresponding to different masses of samples loaded into the measuring cell in comparison with the saturated heat capacity (Equation ), isochoric heat capacity corresponding to the cell's volume calculated using NIST Chemistry Webbook 16 and the values of the isobaric and isochoric heat capacities calculated from the experimental data along the saturation line 19 . It should be pointed out that the correcting terms, which use the first and the second derivatives of the saturated vapor pressure in (21a) and (21b) are sufficiently smaller than с p values for the whole interval of temperatures, see Figure 2, where the solid and the dashed curves show the ratios

T ((), \frac{v^{t}}{m} - \frac{1}{ρ^{l}}) {(\frac{\partial^{2} p}{\partial T^{2}})}_{σ} \frac{100 %}{с_{σ}} and \frac{T}{ρ^{l 2}} {(\frac{\partial ρ^{l}}{\partial T})}_{σ} {(\frac{\partial p}{\partial T})}_{σ} \frac{100 %}{с_{σ}},

…”

Section: Resultsmentioning

confidence: 99%

“…Specific heat capacities, c , of n ‐heptane as a function of temperature— orthobaric heat capacities (upper branches of curves), c σ , and heat capacities at constant volumes (lower branches of curves), c V , experimental data obtained for the different weight of sample loaded into the measuring cell: m = 7.0555 g (green curve), m = 6.8363 g (blue curve), m = 6.8329 g (cyan curve) m = 6.7245 g (red curve), m = 6.7208 g (magenta curve), m = 6.3407 g (yellow curve) and collected in File S1. Asterisks and circles show experimental‐based data for c p and c V 19 ; solid line denote DIPPR‐based heat capacity at saturation, dash‐dotted black line corresponds to c V based on its value and data for the density, isobaric expansion coefficients and the internal pressure; dotted black line presents c V data from NIST Chemistry Webbok 16 . Vertical lines denote locations of the complete cell's filling for all samples colored, respectively [Color figure can be viewed at wileyonlinelibrary.com]…”

Section: Resultsmentioning

confidence: 99%

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Jumping transition in the liquid's heat capacity revealed by the scanning transitiometry

Chorążewski

Randzio

Wilhelm³

et al. 2021

AIChE Journal

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This manuscript reports the direct observations of the clear jump transition of the specific orthobaric heat capacity to the specific isochoric heat capacities during the continuous heating of liquid samples in a closed vessel as well as the respective theory explaining such effects. The measurements have been performed with n‐heptane and toluene and the results have been thoroughly analyzed with the derived equations and compared with the values from the known literature data. The detection and accurate tracking of a jump in the heat capacity far from the standard points of phase transitions are not only of fundamental thermodynamic interest but also demonstrates future research targets and now attainable data which can be achieved by modern calorimetric technology. It has been proven that by using high‐pressure scanning calorimeter (transitiometry technology) it is possible to directly measure the specific orthobaric heat capacities and specific isochoric heat capacities accurately.

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c_{p} - c_{v} = - T \frac{{([], {((), \frac{\partial V}{\partial T})}_{p})}^{2}}{{((), \frac{\partial P}{\partial V})}_{T}},

α_{p} = \frac{1}{V} {(\frac{\partial V}{\partial T})}_{p} and κ_{T}^{- 1} = - V {(\frac{\partial P}{\partial V})}_{T}

…”

Section: Resultsmentioning

confidence: 90%

T ((), \frac{v^{t}}{m} - \frac{1}{ρ^{l}}) {(\frac{\partial^{2} p}{\partial T^{2}})}_{σ} \frac{100 %}{с_{σ}} and \frac{T}{ρ^{l 2}} {(\frac{\partial ρ^{l}}{\partial T})}_{σ} {(\frac{\partial p}{\partial T})}_{σ} \frac{100 %}{с_{σ}},

…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Jumping transition in the liquid's heat capacity revealed by the scanning transitiometry

Chorążewski

Randzio

Wilhelm³

et al. 2021

AIChE Journal

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“…The compressibility β τ has been measured several times 30 ' 31 and the thermal pressure coefficient at least twice (Westwater et a/. The dispersion-free speed of sound is reviewed by Zotov and his colleagues 91 . The heat capacity C p is particularly accurately known at room temperatures and below 86 ' 88 , since n-heptane has been chosen as a calorimetric sub-standard 89 .…”

Section: N-heptanementioning

confidence: 99%

The thermodynamic properties

Rowlinson

Swinton

1982

Liquids and Liquid Mixtures

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“…( 8), the relationship between • and u is determined by two empirical constants a and b. Using numerical values of the coefficient of thermal activity [5] and u [6] for water and values of • [7][8][9] and u [10,11] for toluene, we were able to establish the character of the dependences of coefficients a and b of Eq. ( 8) on temperature.…”

Section: = ~; + B (-U;)mentioning

confidence: 99%

Relationship between thermal conductivity, speed of sound, and isobaric heat capacity of liquids

Mamedov¹

1980

Journal of Engineering Physics

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difference of 5-10~ although the data in Tables 1 and 2 lead us to expect that this error would be less for the platinumrhodium-platinum thermocouples. Such a large error is possibly a reflection of inexact positioning of the thermocoupIe junctions relative to the specimen height and the insulation of the electrodes, and it is always present in these experiments despite precautions that are taken. Thus, the complete study shows that platinum-rhodium-platinum thermocouples offer no distinct advantages over Chromel-Alumel thermocouples in determining the thermal conductivity of solids in an actual thermophysical experiment. NOTATION T, t, temperature; ,~, temperature difference; Ay, thermocouple readings; A i, parameters of approximating equation; 3, sensitivity of thermocouple; ~-g>, sensitivity found from the generalized function; 3st, "standard" values of sensitivity; So, standard deviation of sensitivity for a given series; 5, maximum deviation of 3 from ~$> in different series; I, II, indices indicating that the values pertain to platinum-rhodium-platinum and Chromel-Alumel thermocouples, respectively.

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Some thermodynamic properties of n-heptane on the saturation line

Cited by 5 publications

References 1 publication

Jumping transition in the liquid's heat capacity revealed by the scanning transitiometry

Jumping transition in the liquid's heat capacity revealed by the scanning transitiometry

The thermodynamic properties

Relationship between thermal conductivity, speed of sound, and isobaric heat capacity of liquids

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