Pycnometer method

The concentration of distilled glycerol is easily determined from its specific gravity (15) by the pycnometer method (16) with a precision of 0.02%. Deterrnination of the refractive index also is employed (but not as widely) to measure glycerol concentration to 0.1% (17). 

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. 

Other Measurements. Particle size distributions were measured by the Coulter Counter method. Absolute density measurements were made using the well known pycnometer method. 

Pycnometer Method. Sp gr shall be detd in accordance with Federal Test Method No 141 Method 4183, except that the temperature shall be 20/20QC... 

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... 

Analytical Methods of Powder Analysis , Bofors, Sweden (I960), 22 (Mohr-Westphal Balance Method), 22-23 (Pycnometer Method), 23 (Bulk Density), 172 (Modified Bianchi Method for detg sp gr of smokeless proplnts), and 173 (Bulk Density detn of smokeless proplnts)... 

The apparent density of coal is determined by immersing a weighed sample of coal in a liquid followed by accurate measurement of the liquid that is displaced (pycnometer method). For this procedure, the liquid should (1) wet the surface of the coal, (2) not absorb strongly to the coal surface, (3) not cause swelling, and (4) penetrate the pores of the coal. 

It is difficult (if not impossible) to satisfy all of these conditions, as evidenced by the differing experimental data obtained with solvents such as water, methanol, carbon tetrachloride, benzene, and other fluids. Thus, there is always the need to specify the liquid employed for the determination of density by means of this (pycnometer) method. Furthermore, a period of 24 hours may be necessary for the determination because of the need for the liquid to penetrate the pore system of the coal to the maximum extent. 

Specific Gravity. Shall be not less than 1.2620 at 15.5/15.5°. Any method that is accurate within two points in the 4th decimal place may be used. The most convenient is the pycnometer method (See Vol 3 of Encyd, p D69-L)... 

Following are some density values as detd by pycnometer method... 

Part 10 of ISO 787 gives a pycnometer method of density determination." Two methods are suggested. One method uses simple wet pycnometer in which the sample displaces water or some other liquid and the result is determined by a gravimetric method. The other method uses vacuum to remove air from the sample followed by the introduction of a portion of the liquid under vacuum. There is an inevitable difference in the results and the precision of each method. The differences in the determined values may also come from the choice of liquid used for displacement. 

Determination of the density of granular sohds was described by F. Patat and K. Kirchner, Praktikum der technischen Chemie, Walter de Gruyter, Berlin, 4th ed., 1986, pp. 46,47 (pycnometer method). Guidelines can also be found on the internet. Possible problem the pores of porous materials must be filled with hquid ... 

The second method is called the pycnometer method. A pycnometer is a glass beaker of defined volume. It is shown in Figure 2.65. 

Part 7 Determination of the particle density of filler — Pycnometer method... 

---