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Densities (ρ) and speeds of sound (u) data for the binary mixtures of benzyl alcohol (BA) with methyl ethyl ketone (MEK), diethyl ketone (DEK), methyl propyl ketone (MPK), and methyl isobutyl ketone (MIBK) have been investigated at four temperatures (T = 303.15, 308.15, 313.15 and 318.15 K) and pressure (P = 0.1 MPa) over the entire composition range. These data have been utilized to derive excess molar volume ( V m E ), excess isentropic compression ( K S E ) and excess speed of sound ( u E ) for all the systems. The experimentally determined values have been correlated by Redlich-Kister polynomial equation. Further, these results have been analysed by different theoretical treatment such as Prigogine–Flory–Patterson (PFP) theory, intermolecular free length theory and collision frequency theory. The different types of interaction between the component molecules could be addressed by the changes in positive and negative values of excess properties. The applications of present study can be used to build comprehensive theoretical models for designing various technological processes in chemical and biochemical industries.

Ionic liquids are used in different processes owing to their low vapor pressure, large viscosity range, chemical and thermal stability, and superior conductance even without water. These features make them flexible and tunable, indicating their possible use as substitutes for commonly used compounds in many processes. The objective of this study was to evaluate the properties of aqueous binary solutions for three different ionic liquids (ILs): dibutylammonium acetate, dibutylammonium propanoate, and dibutylammonium butanoate. The measured properties were density, speed of sound, and conductivity, and their isentropic compressibility and thermal expansion coefficient were calculated based on these properties. The temperature range used for measurements was 293.15–323.15 K. Mathematical models were used for each ionic liquid + water mixture to fit the density and speed of sound data. The increase in the alkyl chain leads to a tendency to decrease the values of density, speed of sound, and conductivity of the solutions. However, decreasing the dilution in water, the density, the conductivity and the speed of sound initially increase and then decrease, exhibiting a maximum in the initial water concentration range which indicates the formation of aggregates. Critical micellar concentrations at 298 K were determined through conductivity data. Enhancing the temperature leads to a decrease on density and sound velocity. Supplementary Information The online version contains supplementary material available at 10.1007/s43153-021-00174-7.

This work reported the experimental data of densities, speed of sound, and refractive index of a binary mixture containing ethyl isobutyrate and cyclohexane at different temperatures (293.15, 298.1...

In the present work, we obtained density (ρ123), speed of sound (u123), excess molar volume (Vm123E), and deviation in isentropic compressibility (Δks123) for ternary mixtures of {[BMIM][BF4] (x1) ...

The density, speed of sound and viscosity data of drug pentoxifylline in aqueous solutions of glucose (monosaccharide) and lactose (disaccharide) were determined. The various properties of the solutions were characterized and their structural features determined by varying the concentrations of solute and solvent at atmospheric pressure and at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15) K. Infinite dilution limiting apparent molar volume ( $$V_{\phi }^{0}$$ ) and limiting apparent molar isentropic compression ( $$K_{\phi ,S}^{0}$$ ) parameters and their variation tendencies were considered in terms of the interactions between solute and solvent. The transfer parameters ( $$\Delta_{{{\text{tr}}}} V_{\phi }^{0}$$ and $$\Delta_{{{\text{tr}}}} K_{\phi ,S}^{0}$$ ) were positive and increased with increase in the concentrations of glucose/lactose in aqueous medium. Limiting apparent molar expansivity ( $$E_{\phi }^{0}$$ ), Hepler’s constant $$\left( {{{\partial^{2} V_{\phi }^{0} } \mathord{\left/ {\vphantom {{\partial^{2} V_{\phi }^{0} } {\partial T^{2} }}} \right. \kern-\nulldelimiterspace} {\partial T^{2} }}} \right)$$ and hydration number (nH) were also evaluated. The viscosity data have also been evaluated using the Jones–Dole equation. The results, analyzed using spectroscopic data, are discussed and rationalized in terms of various interactions.

Density (ρ), speed of sound (u), viscosity (n) and refractive index (nD) of binary liquid mixtures comprising of N-vinyl-2-pyrrolidinone + 1-butanol, + 1-pentanol, + 1- hexanol and + 1-heptanol are...

The interaction in the binary solution of polyethylene glycol 200 (PEG 200) and polyethylene glycol 400 (PEG 400) with d-panthenol at the variation of temperatures has been surveyed by merging acoustic and volumetric processes. The density and speed of sound of PEG 200 and PEG 400 mol $${\mathrm{kg}}^{-1}$$ in the aqueous solution of d-panthenol in the concentrations of (0.00, 0.03, 0.06 and 0.09) at temperature, T = (288.15, 298.15, 308.15 and 318.15) K and experimental pressure 0.1 MPa is measured. From the data of density, the apparent molar volume $${(V}_{\phi })$$ , partial molar volume $${(V}_{\phi }^{0})$$ and partial molar volume of transfer $$(\Delta {V_{\phi }^{0}} )$$ , for PEG 200 and PEG 400 in the aqueous solution of d-panthenol is calculated along with the apparent molar isentropic compression $${(K}_{\phi })$$ , partial molar isentropic compression $${(K}_{\phi }^{0})$$ and the partial molar isentropic compression of transfer, $$(\Delta {K_{\phi }^{0}} )$$ , from the of the speed of sound data. Using the partial molar volume of transfer and partial molar isentropic compression of transfer the pair and triplet coefficients as the functions of temperatures are calculated as well as the partial molar expansibilities ( $${E}_{\phi }^{0}$$ ) with its first-order derivative $$\left( {\partial {E_{\phi }^{0}} /\partial T} \right)_{P}$$ are obtained. Further, these calculated parameters are used to describe the results in terms of (solute–solute); (solute–solvent) interactions including the structure making/breaking ability of polyethylene glycols in the aqueous solution of d-panthenol.

The need to predict acoustic propagation through marine sediments that contain gas bubbles has become increasingly important for civil engineering and climate studies. There are relatively few in situ acoustic wave propagation studies of muddy intertidal sediments, in which bubbles of biogenic gas (generally methane, a potent greenhouse gas) are commonly found. We used a single experimental rig to conduct two in situ intertidal acoustical experiments to improve understanding of acoustic remote sensing of gassy sediments, eventually including gas bubble size distributions. In the first experiment, we measured sediment sound speed and attenuation between four aligned hydrophones for a quasi-plane wave propagating along the array. The second experiment involved a focused insonified sediment volume created by two transducers emitting coincident sound beams at different frequencies that generated bubble-mediated acoustic signals at combination frequencies. The results from sediment core analyses, and comparison of in situ acoustic velocity and attenuation values with those of water-saturated sediments, together provide ample evidence for the presence of in situ gas bubbles in the insonified volumes of sediments. These datasets are suitable for linear and non-linear inversion studies that estimate in situ greenhouse gas bubble populations, needed for future acoustical remote sensing applications.

Aim of the study: At present, there are few scatter particles used in preparing blood-mimicking fluids, such as nylon, sephadex, polystyrene microsphere, and poly(4-methystyrene). In this study, we present cholesterol as a new scatter particle for blood-mimicking fluid preparation. Materials and methods: The procedure for the preparation of the proposed blood-mimicking fluid involved the use of propylene glycol, D(+)-Glucose and distilled water to form a ternary mixture fluid, with cholesterol used as scatter particles. Polyethylene glycol was first used as part of the mixture fluid but the acoustic and physical properties were not suitable, leading to its replacement with D(+)-Glucose, which is soluble in water and has a higher density. A common carotid artery wall-less phantom was also produced to assess the flow properties. Results: The prepared blood-mimicking fluid with new scatter particles has a density of 1.067 g/cm3, viscosity of 4.1 mPa.s, speed of sound 1600 m/s, and attenuation of 0.192 dB/cm at 5 MHz frequency. Peak systolic velocity, end diastolic velocity and mean velocity measurements were gotten to be 40.2 ± 2.4 cm/s, 9.9 ± 1.4 cm/s, and 24.0 ± 1.8 cm/s, respectively. Conclusion: Based on the results obtained, the blood-mimicking fluid was found suitable for ultrasound applications in carotid artery wall-less phantoms because of its good acoustic and physical properties.

Density, speed of sound and viscosity data for the binary mixtures (1,4-dioxane (1) + water (2)), were measured over the whole composition range at temperatures T = (295.15, 298.15, 301.15, 304.15, 307.15, 310.15 and 313.15) K and at the atmospheric pressure. From experimental data, the excess molar volume, isobaric thermal expansion coefficient, excess of isobaric thermal expansion coefficient, excess speed of sound, isentropic compressibility, excess of isentropic compressibility, intermolecular free-length, the excess intermolecular free-length, the viscosity deviation, the excess free Gibbs energies of activation of viscous flow, the internal pressure, excess internal pressure, acoustic impedance, the excess acoustic, and the free volume were calculated. The excess parameters were fitted by the Redlich–Kister polynomial equation to derive the coefficients and estimate the standard error values. The nature of molecular interactions between the two components of the mixture, have been discussed by means of the thermodynamic properties.

Measurements of density and speed of sound are reported for phenylboronic acid–water solutions for molalities ranging from 0.0098 to 0.1490 mol⋅kg−1 and temperatures ranging from 288.15 K to 313.15 K. Several thermodynamic parameters for phenylboronic acid–water solutions have been calculated from the experimental data. The capability of phenylboronic acid to have strong solute–solvent interactions and weaker solute–solute interactions in aqueous solutions has been revealed and the results of this investigation are consistent with molecular model images generated using Spartan 04 modeling.

Several thermodynamic parameters for trans-resveratrol have been experimentally determined or calculated at different temperatures. The capability of trans-resveratrol to have strong solute–solvent interactions and weak solute–solute interactions in ethanol solution has demonstrated using density and speed of sound data. Furthermore, its ability to have structure breaking tendencies and the absence of caging effects are shown. The results of this investigation are consistent with molecular model images generated using Spartan 04 modeling.

Under atmospheric pressure, the density, viscosity and speed of sound of the binary system of octamethylcyclotetrasiloxane (D4) with diesel fuel’s main components n-decane, n-dodecane, n-tridecane and n-tetradecane were measured at T = 288.15 to 328.15 K. The excess molar volume, viscosity deviation, excess Gibbs activation energy of viscous flow, isobaric thermal expansivity and isentropic compressibility deviation were calculated from the experimental data. The results indicate that the interactions among mixed systems are somewhat weaker than those in pure components.

Nitrogen is proposed as a suitable driver gas candidate for the operation of free-piston-driven shock tunnels at low total enthalpies. When compressed adiabatically, nitrogen has a lower speed of sound than the commonly used driver gases, e.g., argon and helium, thus providing the ability to achieve tailored conditions and longer test durations at lower enthalpies. This paper describes the methodology used to design operating conditions using nitrogen as the driver gas and presents an experimental and numerical demonstration of its use to achieve tailored conditions in a free-piston-driven shock tunnel. In this demonstration, the useful test flow duration was extended from less than 0.5 ms to 4 ms based on a constant-nozzle-supply-pressure criterion for tests at total enthalpies of 1.6 MJ/kg. The same design methodology was then used to develop different nitrogen–argon driver conditions for tailored operation in the free-piston-driven shock tunnel T4 for enthalpies spanning from 1.6 to 3.2 MJ/kg. With a nitrogen driver gas, T4, which was originally designed for operation up to Mach 25 flight conditions, can now operate at conditions as low as an equivalent flight Mach number of 5.5. This is significant because the experimental results, supported by numerical simulations, clearly demonstrate that nitrogen can be used as a driver gas in free-piston-driven shock tunnels to maximise the duration at which test conditions are held constant when testing at low total enthalpies.

This study carries out the numerical simulation of the propane pyrolysis process in a flow-through chemical reactor where chemical conversions are induced by the external heating of the reaction zone. Navier–Stokes equations in the approximation of small Mach numbers are used for the mathematical description of the studied processes, since the velocity of the gas mixture is much lower than the speed of sound in this mixture. The difference scheme is constructed by the integro-interpolation method. The equations of chemical kinetics are solved by a specialized explicit scheme of the second order of accuracy with low computational complexity. As a base for describing the chemical conversions of propane pyrolysis, a well-known kinetic scheme, which includes 30 elementary stages, is employed. However, for a more accurate description of the process, the activation energy of one of the reaction stages is adjusted. The propane pyrolysis process is numerically simulated, taking into account the processes of viscosity, diffusion, and thermal conductivity for various temperatures of the heating elements. Our results on the conversion of propane are compared with the experimental data and well-known numerical results of solving this problem. It is concluded that the developed numerical algorithm confirms the reliability of the results and can be applied in practice to simulate the investigated processes.

The speed of sound in 3,3,3-trifluoropropene (R-1243zf) in the gaseous phase has been measured using a fixed-path cylindrical resonator. The experiment was conducted along nine quasi-isochoric line...

Experimental values of density (ρ), viscosity (η) and speed of sound (u) of five non-ideal binary {solvent + co-solvent} liquid mixture systems, namely isoamyl alcohol (IAA) + ethanol (EA), isoamyl alcohol + 1,2-ethanediol (EDO), isoamyl alcohol + 1,3-propanediol (PDO), isoamyl alcohol + 1,4-butanediol (BDO) and isoamyl alcohol + glycerol (GLY) have been measured over the whole composition range of mole fraction at T = (298.15–308.15) K with 5 K temperature intervals under atmospheric pressure. According to the ρ, η, and u data, the values of excess volume (VE), deviation in viscosity (∆η), and deviation in isentropic compressibility (∆κs) were calculated. The negative values of VE and ∆κs and positive values of Δη obtained for the studied binary liquid systems are indicative of strong intermolecular interactions between unlike molecules. Further, the effects of the number of –OH groups in polyols, as well as the influence of temperature on thermodynamic parameters, were analyzed. Furthermore, the calculated values of VE, ∆η, and ∆κs were correlated with the Redlich–Kister (R–K) model and reasonable standard deviations were obtained.

Densities, ρ, speed of sound, c, and refractive indices, n, were measured for the binary mixtures of 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) + 2-propanol, 2-butanol, 2-pentanol, and 2...

An experimental study has been made of the density and the velocity of sound for liquid decalin and cyclohexane in the range of temperatures 298.15–433.15 K and pressures 0.1–100.1 MPa. Parameters of equations have been obtained that describe the dependences of the specific volume of liquid decalin and cyclohexane on their temperature and pressure and of the isobaric heat of these substances on their temperature at atmospheric pressure. The density, the velocity of sound, the isobaric and isochoric heats, the isobaric expansion coefficient, and the coefficients of isentropic and isothermal compressibilities of liquid decalin and cyclohexane have been determined in the range of temperatures 298.15–433.15 K at pressures to 100 MPa.

The measured data (549 points) of density, (ρ), speed of sound, (u), and refractive index, (nD) are presented in this work for binary and ternary mixtures containing dibutyl ether (DBE), 1-butanol,...

Experimental data of excess enthalpy, (HE), density, (ρ), speed of sound, (u), and the refractive index, (nD), are reported in this work for ternary and binary mixtures composed of diethylene glyco...

The densities (ρ), viscosities (η), and speeds of sound (u) are reported for binary mixtures of 2-methylcyclohexanone with ortho-substituted anilines (2-chloroaniline, 2-methylaniline and 2-methoxy...

Based on a numerical analysis of experimental data on the speed of sound and the thermal expansion coefficient of water, a detailed thermodynamic description of its properties is presented in the pressure range of 1 bar < p < 9 kbar and temperatures of 0 < t < 100°C. This range of pressures and temperatures is considered the one most interesting from the viewpoint of studying the microstructure of water.

The non-linearity acoustic parameter (B/A) has been computed for six pure liquid metal alloys (Na, K, Rb, Cs, Pb and Sn), four liquid metal alloys (K-Rb, Na-Cs, Pb-Sn and Na-K) and other several liquid metals at different temperatures. This parameter has been calculated by using three different approaches viz. Hartmann method, Ballou rule and Johnson et al. method. The input data required density, sound speed and thermal expansivity were taken from literature. A comparative study has been carried out and quite satisfactory results are obtained.

This paper presents some main characteristics of the distributions of temperature, salinity, chlorophyll-a, and sound speed, which were measured in the Da Nang and Quy Nhon waters in July, 2010. The CTD was deployed for measuring profiles of temperature and salinity at stations. The data showed that in the Da Nang water, concentration of chlorophyll-a ranged from 0.07 mg/l to 1.52 mg/l and decreased toward the offshore region. In the Quy Nhon water, concentration of chlorophyll-a varied from 0.05 mg/l to 1.43 mg/l. This concentration was quite small and homogenous from the surface to 28 m depth. The speed of sound in seawater was maximum with value of 1,543.8 m/s in the Da Nang transect while the water layer with the sudden change of sound speed was from 5 m to 10 m deep in nearshore region (from stations D1 to D4), and from 10 to 15 m deep in offshore region (in D5 and D6 stations). Its minimum value in the Da Nang transect is just 1,014 m/s in the bottom. In the Quy Nhon transect, the maximum value of sound speed in seawater was 1,545.2 m/s and the minimum value was 1,515.2 m/s. The nearshore sound velocity reaches its maximum in the surface layer down to 30 m deep and the offshore one is similar down to about 40 m deep, under which, the sound velocity declines steadily.

The densities and speed of sound for liquid mixtures containing vitamin B3 (niacin) at 0.01, 0.03, and 0.05 mol·kg-1 concentrations in aqueous propylene glycol and hexylene glycol at the variation of temperatures from 293.15 to 308.15 K have been measured using an Anton Paar DSA 5000 M. From volumetric experimental data, apparent molar volume (V ϕ), partial molar volume (V ϕ 0), and partial molar volume of transfer (ΔV ϕ 0) are calculated along with the apparent molar isentropic compression (K ϕ, S ), partial molar isentropic compression (K ϕ, S 0), and partial molar isentropic compression of transfer (ΔK ϕ 0) using experimental acoustic data. The positive volumetric data (i.e., apparent molar volume and partial molar volume) indicates strong solute-solvent interactions inside the mixture. Along with these values, the empirical constants a, b, and c with the pair and triplet coefficients (V AB, V ABB, K AB, K ABB) are also calculated.

The densities (ρ), speeds of sound (u), and viscosities (η) are reported for binary mixtures of propiophenone with ortho-substituted aniline (2-chloroaniline, 2-methylaniline, and 2-methoxyaniline) over the entire composition range from 303.15 to 318.15 K and at atmospheric pressure 0.1 MPa. The excess/deviation functions (VE, $$k_{s}^{E}$$ , and Δη) are calculated from the measured densities, speeds of sound and viscosities at experimental temperatures. The excess properties have been analyzed through molecular interactions. The FT-IR data indicate that the formation of intermolecular hydrogen bonding (N–H⋅⋅⋅O–H) between hydrogen atom of amine group of o-substituted aniline and oxygen atom of carbonyl of propiophenone in the binary liquid mixtures.

The interlinkage of ethylene glycol, diethylene glycol and triethylene glycol with d-mannitol at different values of temperature has been analysed by the combination of volumetric and acoustic process. Different values of speed of sound and the density of EG, DEG and TEG in the molalities of (0.01, 0.03 and 0.05) mol kg−1 in aqueous solutions of d-mannitol at T = (293.15, 298.15, 303.15 and 308.15) K have been considered. From the values of speed of sound, the partial molar isentropic compression (Kϕ,s) and the partial molar isentropic compression of transfer $$(\Delta {\rm K}_{{\phi ,{\text{s}}}}^{0}$$ ), have been determined. The pair and triplet interaction coefficient have also been estimated. From the density data, the apparent molar volume $$(V_{\phi }^{0}$$ ) and standard partial molar volume of transfer $$(\Delta V_{\phi }^{0} )$$ for EG, DEG and TEG in aqueous d-mannitol solutions have been examined. Using the values of partial molar volume and partial molar isentropic compression of transfer, the pair and triplet coefficients are determined. These noteworthy parameters are helpful to examine the interactions between sugar alcohol + glycols + water solutions.

Methods for measuring the composition of a binary gas mixture using the dependence of the speed of sound in a gas on its molecular weight, in particular, using an acoustic resonator, are considered. The described atmospheric hydrogen sensor target station for the cyclotron of the S-70 accelerator, which allows the production of medical isotopes, as well as a sensor for the content of neon in helium during its liquefaction, was developed based on this principle at the Kurchatov Institute IHEP SIC. Optimization of the resonator characteristics allowed a resolution of 10–5.

This paper presents the observational report of the authors on measured density (ρ), speed of sound (u) of pure liquids of Ethyl propionate (EP), and various renewable oxygenated fossil fuels (1,2-...

In the present study, to investigate the soluting effect in ternary aqueous solutions of ionic liquids (ILs), experimental studies have been carried out on ionic liquid 1 + ionic liquid 2 + water systems that are in isopiestic equilibrium. The imidazolium-based ionic liquids 1-ethyl-3-methyl-imidazolium bromide ([C2MIM]­Br), 1-butyl-3-methylimidazolium bromide ([C4MIM]­Br), and 1-hexyl-3-methylimidazolium bromide ([C6MIM]­Br) were selected, and the vapor–liquid equilibria (VLE) of {[C2MIM]Br + [C6MIM]Br + water}, {[C2MIM]Br + [C4MIM]Br + water}, and {[C4MIM]Br + [C6MIM]Br + water} were investigated by the isopiestic method. The equations derived from the Zdanovskii–Stokes–Robinson rule were applied to predict the thermodynamic properties (density, speed of sound, and surface tension) of ternary solutions from the corresponding data of binary subsystems with the same water activity data, and the calculated thermodynamic properties were compared to the experimental data.

Mixtures of n-dodecane with C10H14 aromatic isomers (iso-butylbenzene, sec-butylbenzene, tert-butylbenzene, and 1,3-diethylbenzene) were analyzed for density, viscosity, speed of sound, surface ten...

A finite-element method study was conducted on a laboratory-scale partially premixed combustor, for investigating the characteristics of combustion instability due to fuel composition variations. The authors’ previous studies reported frequency mode shifting in the same combustor with hydrogen enrichment, and the cause of this phenomenon was analyzed only from the viewpoint of the flame shape change and time lag theory. An increase in hydrogen fraction results in an increase in the speed of sound in the fuel feeding line, resulting in an increase in resonant frequencies determined by the fuel line geometry. This analysis shows that the hydrogen enrichment increases the bulk and longitudinal resonant frequencies of the fuel feeding line. When one of these fuel line resonances is coupled with the intrinsic acoustic mode of the combustor, the hydrogen fraction can be one of the key parameters affecting the main characteristics of combustion instability in a partially premixed system.

The present work includes density and speed of sound measurements of cationic surfactant, dodecyltrimethylammonium bromide (DTAB), and anionic surfactant, sodium dodecylsulphate (SDS), in aqueous s...

In this study, measurements regarding the density and speed of sound for binary liquid mixtures of the 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) ionic liquid (+ methanol, or + a...

Isobaric vapor–liquid equilibria (VLE) at 50.0, 101.3, and 200.0 kPa, have been measured for the binary system methyl nonafluorobutyl ether (x1) HFE-7100 + (1 – x1) 2-propanol. Thermodynamic consis...

Density and speed of sound data for dilute aqueous solutions of two poly(ethylene glycol) monoalkyl ethers, H–(CH2)n–(O–CH2–CH2)m–OH for n = 4, m = 2 and n = 1, m = 3, were measured using the Anton...

In this work, to obtain evidence about the salting-out effect, a set of thermophysical properties, namely, density and speed of sound measurements were determined for the systems containing the ion...

An original method of calculating isochoric and isobaric heat capacity based on the fundamental relationships of thermodynamics is presented. The theoretical development of the methodology for calculating isochoric and isobaric heat capacity can be used to obtain high metrological data on the thermophysical properties of new low-boiling working substances of power plants operating on the Rankine organic cycle and to replenish existing databases. The technique allows the use of heterogeneous experimental results of acoustic and thermal measurements to calculate the basic thermodynamic functions without information about the values of ideal gas functions, and also to evaluate the consistency of experimental data. Formulas are derived for calculating isobaric and isochoric heat capacities, which are based on reliable equations describing experimental data on the speed of sound and density depending on state parameters. The method was tested using both the characteristics of the reference substances (H2O and CO2), and own new experimental data on the thermal and acoustic properties of octafluorocyclobutane (c-C4F8) in the liquid phase for temperatures of 320 and 340 K and pressures from 4 to 10 MPa. The isochoric heat capacity was calculated from measurements of the density of octafluorocyclobutane and the speed of sound in it. According to the latest series of density measurements in a limited region of the states of the liquid phase of octafluorocyclobutane obtained by the constant volume piezometer method, the isochoric heat capacity was calculated using the equation proposed in this work. The uncertainty of the experimental data used for the test calculation of the density did not exceed 0.25%, and the speed of sound did not exceed 0.05%. The standard deviation in the description of the dependence of thermal quantities was 0.23%, and acoustic—0.15%.

The density (ρ), speed of sound (u), and refractive indices (nD) data at atmospheric pressure for benzene + n-heptane + n-octane mixtures from 298.15 to 318.15 K have been measured. The data were f...