The Density of Liquids

An empty and dry pycnometer weighs 23.4532 g and has a volume of 10.00 mL at 20°C. When filled with hexane it weighs 30.0532 g. What is the density of the hexane  

FIGURE 15.16 An aluminum pycnometer assembled (left) and disassembled (right). The quarter in the photos is to indicate the size of the pycnometer. 

Research and development technologists at the Dow Chemical Company can characterize materials in a variety of ways. One material property that is especially critical in polymer foaming and processing technology is density. A tool used for measuring the density of a material is called a pycnometer. There are many different manual and automatic types to choose from. For extremely accurate and precise density measurements, an easy-to-use, fully automatic gas displacement pycnometer is utilized. Analyses are commenced with a single keystroke. Once an analysis is initiated, data are collected, calculations performed, and results displayed without further operator intervention. 

Dow technologist Kenn Bouchard utilizes an automatic gas displacement pycnometer for measuring density in materials characterization. 

The mass of the hexane is determined by subtracting the mass of the empty pyconometer from the mass of the filled pycnometer. 

---

Alternatively, expansion of equation (A2.5.1). equation (A2.5.2) or equation (A2.5.3) into Taylor series leads ultimately to series expressions for the densities of liquid and gas, / and p, in temis of their sum (called the diameter ) and their difference ... 

The density of liquids, unless otherwise stated, is given at 15°C. 

Determine the capacity, cross-sectional area and diameter of a continuous sedimentation tank for liquid suspension clarification in the amount of = 20,000 kg/hr. The concentration of solids is x, = 50%, the settling velocity is Uo = 0.5 m/hr, and the density of liquid phase is 1,050 kg/mT... 

The density of liquid butane and propane is about half that of water, and as such is much lower than other liquid fuels. 

The density of liquid carbon dioxide at room temperature is 0.80 grams/ml. How large a cartridge of liquid C02 must be provided to inflate a life jacket of 4.0 liters capacity at STP ... 

C02-0074. Mercury is an unusual metal in that it is a liquid at room temperature. The density of liquid mercury is 13.55 g/mL. The photo shows a sample of mercury in a graduated cylinder. How many atoms of mercury are in the sample ... 

C04-0142. One set of reactants for rocket fuel is hydrazine and hydrogen peroxide, which react vigorously when mixed N2 H4(/) +H2 02(/) N2(g) + H2 0(g) (unbalanced) The density of liquid hydrazine is 1.44 g/mL, and that of hydrogen peroxide is 1.01 g/mL. What volume ratio of these two liquids should be used if both fuels are to be used up at the same time ... 

In bubbling, the control of the bubble diameter is a little easier. In these methods bubbles are made at an orifice or a multitude of orifices. If there is only one orifice, of radius r, and if bubble formation is slow and undisturbed, the greatest possible bubble volume is 27rry/gp] y is the surface tension of the liquid, p the difference between the densities of liquid and gas (practically equal to the density of the liquid), and g is acceleration due to gravity. Every type of agitation lowers the real bubble size. On the other hand, if there are many orifices near enough to each other, the actual bubble may be much larger than predicted by the above expression. 

The density of a material is a function of temperature and pressure but its value at some standard condition (for example, 293.15 K or 298.15 K at either atmospheric pressure or at the vapor pressure of the compound) often is used to characterize a compound and to ascertain its purity. Accurate density measurements as a function of temperature are important for custody transfer of materials when the volume of the material transferred at a specific temperature is known but contracts specify the mass of material transferred. Engineering applications utilize the density of a substance widely, frequently for the efficient design and safe operation of chemical plants and equipment. The density and the vapor pressure are the most often-quoted properties of a substance, and the properties most often required for prediction of other properties of the substance. In this volume, we do not report the density of gases, but rather the densities of solids as a function of temperature at atmospheric pressure and the densities of liquids either at atmospheric pressure or along the saturation line up to the critical temperature. 

The purpose of this compilation is to tabulate the densities of compounds, hence only minimal description of experimental methods used to measure the density of liquids or solids appears. Detailed descriptions of methods for density determination of solids, liquids and gases, along with appropriate density reference standards, appear in a chapter by Davis and Koch in Physical Methods of Chemistry, Volume VI, Determination of Thermodynamic Properties [86-ros/bae],... 

The principal experimental method used to measure the density of a solid is determination of the mass of liquid displaced by a known mass of solid. It is essential that the solid have no appreciable solubility in the liquid, that all occluded air be removed from the solid and that the density of the displacement fluid be less than that of the solid lest the solid float. Densities of crystalline solids also can be determined from the dimensions of the unit cell. Davis and Koch discuss other methods for measuring the density of liquids and solids such as hydrostatic weighing of a buoy and flotation methods. 

From the three roots, only Z and Z2 are significant. The smallest root (Zj) relates to the liquid and the largest root (Zf) to the vapor. Thus, the density of liquid benzene is given by ... 

Spherical particles 15 nm in diameter and of density 2290 kg/m3 are pressed together to form a pellet. The following equilibrium data were obtained for the sorption of nitrogen at 77 K. Obtain estimates of the surface area of the pellet from the adsorption isotherm and compare the estimates with the geometric surface. The density of liquid nitrogen at 77 K is 808 kg/m3. 

SAQ 10.1 The following data refer to the adsorption of butane at 0°C onto tungsten powder (area 16.7 m2g 1). Calculate the number of moles adsorbed in a monolayer, and hence the molecular area for the adsorbed butane (at monolayer coverage) and compare it with the value of 32 x 10 20 m2 estimated from the density of liquid butane. 

FIG. 5 The density of liquid and supercooled water as a function of temperature, illustrating the anomalous liquid phase density maximum of water (data from Lide, 2002-2003). 

Ap is the difference between the densities of liquid and vapor g is the gravitational constant h is the meniscus height a is the liquid-gas surface tension of water. 

The densities of liquid and solid helium are different thus, AVm of Equation (8.9) is not zero. Yet the horizontal slope of the melting line of the phase diagram shows that dP/dT is zero near 0 K. Hence, it is clear that A5m of Equation (8.9) must be zero at 0 K, that is, that 5m,ok is zero for liquid He as well as for solid He. 

The following equation relates surface tension of a liquid to the density of liquid, pi, and vapor, pv (Partington, 1951 Birdi, 1989) ... 

---