Densimeter

Density of solution and solvent were measurement with Anton Paar densimeter DMA5N. For determining the hydration value is used the following concentrations of gelatin in aqueous solution 0.2, 0.4, 0.5 and 0.6%. 

Density measurements were carried out using an A. Paar digital densimeter (model DMA 100) at a temperature of 298 K over the mass concentration range 0.75 - 6.00kgm -The densimeter was calibrated with water [4] and dry air [5]. 

O.Kratky, H.Leopold, H.Stabinger, Digital Densimeter of Liquids and Gases (A. Paar K. G., A-8054, Graz, Austria). 

The two principal experimental apparatuses used to determine the density of a liquid are the pycnometer and the vibrating tube densimeter. The pycnometer method involves measuring the mass of a liquid in a vessel of known volume. The volume of the pycnometer, either at the temperature of measurement or at some reference temperature, is determined using a density standard, usually water or mercury. Using considerable care and a precision analytical balance accurate to 10 5 g, it is possible to achieve densities accurate to a few parts in 10s with a pycnometer having a volume of 25 cm3 to 50 cm3. 

The vibrating tube densimeter relies upon the fact that the frequency /of vibration for a U or V shaped tube depends upon the mass of material in the tube ... 

Calibration of the apparatus is necessary usually water and air or nitrogen are the reference materials. Vibrating tube densimeters designed to operate close to atmospheric pressure can achieve repeatability of parts in 10s. If the reciprocal of the frequency is linear in density, accuracies of 1 part in 105 are readily achievable. 

The global salt content was measured using a digital densimeter, and is expressed as the density difference of sample water relative to standard distilled water, at 25°C. It is noted as Ad and expressed in units of mg/l. Major solutes within the groundwater samples (Li, Na, K, Mg, Ca, and Sr) were analysed using absorption spectroscopy. 

A. One Atmosphere Densities. The densities or volume properties of solutions have been studied by a number of methods which are extensively reviewed elsewhere (4,5. 6,7) of all of the methods, only the magnetic float (7-14), the hydrostatic balance (3,15-20), the vibrating flow densimeter (21,22), and dilatometric (23,24,25) methods give data with sufficient precision to study the densities of dilute solutions. For more concentrated... 

Vibrating Flow Densimeter. One of the major advances made in making density measurements of solutions was the system developed by Kratky et al. (21) which measures the natural vibration frequency of a tube containing a liquid. The oscillating frequency (f) of the tube is related to its mass (m) by... 

The instrument constant B can be determined by measuring the t in two fluids of known density. Air and water are used by most workers (22). In our laboratory we used seawater of known conductivity and pure water to calibrate our vibrating flow systems (53). The system gives accurate densities in dilute solutions, however, care must be taken when using the system in concentrated solutions or in solutions with large viscosities. The development of commercial flow densimeters has caused a rapid increase in the output of density measurements of solutions. Desnoyers, Jolicoeur and coworkers (54-69) have used this system to measure the densities of numerous electrolyte solutions. We have used the system to study the densities of electrolyte mixtures and natural waters (53,70-81). We routinely take our system to sea on oceanographic cruises (79) and find the system to perform very well on a rocking ship. 

It is easy to see why the results of primordial nucleosynthesis, and in particular the final abundance of deuterium, should be so sensitive to the nucleonic density of the Universe. For this reason, deuterium, made up of one proton and one neutron, can be considered as an excellent cosmic densimeter. The disparate abundances for their part are related to specific nuclear properties of the isotopes under consideration. 

The concentration of the polymer molecules eluting from SEC columns is continuously monitored by a detector. The most widely used detector in SEC is the differential reftactometer (DRI), which measures the difference in refractive index between solvent and solute. Other detectors commonly used for SEC are functional group detectors ultraviolet (UV) and infrared (IR), and absolute molecular weight detectors low angle laser light scattering (LALLS) and in-line continuous viscometers. Applications of these detectors to SEC analysis will be discussed later in the Multiple Detectors Section. Other detectors also being used are the densimeter (11-19) and the mass detector (20-23). 

Methanol. Commercial methanol contains less than 0.3% of water and may be used for the experiments set out herein without additional drying. The water content in it can be controlled by measuring its density with a densimeter (Table 3). 

The densities and volumetric specific heats of some alkali halides and tetraalkylammonium bromides were undertaken in mixed aqueous solutions at 25°C using a flow digital densimeter and a flow microcalorimeter. The organic cosolvents used were urea, p-dioxane, piperadine, morpholine, acetone, dime thy Isulf oxide, tert-butanol, and to a lesser extent acetamide, tetrahydropyran, and piperazine. The electrolyte concentration was kept at 0.1 m in all cases, while the cosolvent concentration was varied when possible up to 40 wt %. From the corresponding data in pure water, the volumes and heat capacities of transfer of the electrolytes from water to the mixed solvents were determined. The converse transfer functions of the nonelectrolyte (cosolvent) at 0.4m from water to the aqueous NaCl solutions were also determined. These transfer functions can be interpreted in terms of pair and higher order interactions between the electrolytes and the cosolvent. 

The British equivalent to ISO 2781 is BS 903 Part Al2 which is identical to the international method. Rather surprisingly, ASTM does not appear to have a specific method for density at the present time. There is, however, a section on density in the standard on chemical analysis of rubber products, D2973, which briefly gives methods by pycnometer, hydrostatic weighing and a compressed volume densimeter. The weighing method does not mention the use of a sinker for densities less than 1. There is also a method for density of rubber chemicals, D1817)4, which uses the pycnometer method and, interestingly, specifies a vacuum pump to remove air before the measurement.. 

Specific Gravity, also called absolute density, is the relation betw wt and volume of grains disregarding che air spaces. The Bofors manual(Ref 10,p 22) describes two methods Mohr-Wesrphal s balance and pycnometer methods. In the BurMines method(Ref 2,p 67), an apparatus called densimeter is used. In US Spec JAN-P-223A(Ref 11) two methods are described in which either a 25-ml bottle with a 10-g sample or a large... 

Densimeters Devices for measuring densities. See under DENSITY SPECIFIC GRAVITY AND THEIR DETERMINATIONS... 

The hydrostatic balance principal has been used in Bode s Densimeter for density detns of large grain expls or proplnts, such as of prismatic BkPdr. Here the prism is weighed first in air and then suspended in mercury at known temp... 

Note The densities of BkPdrs detd by Bianchi s and Snelling s methods are usually 1.65 to 1.85, but the "absolute sp gr as calcd from its constituents runs higher, such as 2.03- This shows that under conditions of detns, many pores in the interior of the grains do not become filled with mercury. In detns of densities of commercial expls by Snelling s densimeter, the values were much higher than those obtained by the "sand method , described here as item v. For example... 

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