Water density of

In Section 2.5.3 we discussed a link between the length domain of measurement and the volume domain, noting that 1 cm is the same as 1 mL. A link also exists between the mass and volume domains. 

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Flence it can be seen that from the density of a fluid, the pressure gradient may be caloulated. Furthermore, the densities of water, oil and gas are so significantly different, that they will show quite different gradients on a pressure-depth plot. 

Density of water Temp., °C Density of mercury Density of water Temp., °C Density of mercury... 

ITi = weight in air of the water required to fill the pyknometer at fC W2 = weight in air of the liquid required to fill the pyknometer at t°C d = density of water in grams per milliliter at fC Sync = specific gravity of the liquid at t°C referred to water at t°C corrected for the buoyant effect of air... 

The values for unit weight of solvent (molality scale) can be obtained by multiplying the corresponding values for unit volume by the square root of the density of water at the appropriate temperature. 

Determinate measurement errors can be minimized by calibration. A pipet can be calibrated, for example, by determining the mass of water that it delivers and using the density of water to calculate the actual volume delivered by the pipet. Although glassware and instrumentation can be calibrated, it is never safe to assume that the calibration will remain unchanged during an analysis. Many instruments, in particular, drift out of calibration over time. This complication can be minimized by frequent recalibration. 

To ensure that S eas is determined accurately, we calibrate the equipment or instrument used to obtain the signal. Balances are calibrated using standard weights. When necessary, we can also correct for the buoyancy of air. Volumetric glassware can be calibrated by measuring the mass of water contained or delivered and using the density of water to calculate the true volume. Most instruments have calibration standards suggested by the manufacturer. 

Relative Humidity (rh). Relative humidity is the ratio of the mole fraction of water vapor present in the air to the mole fraction of water vapor present in saturated air at the same temperature and barometric pressure it approximately equals the ratio of the partial pressure (or density) of the water vapor in the air to the saturation pressure (or density) of water vapor at the same temperature. 

Figure 18 is an entrainment or gas-carryiag capacity chart (25). The operating conditions and particle properties determine the vertical axis the entrainment is read off the dimensionless horizontal axis. For entrainment purposes, the particle density effect is considered through the ratio of the particle density to the density of water. When the entrainable particle-size distribution is smaller than the particle-size distribution of the bed, the entrainment is reduced by the fraction entrainable, ie, the calculated entrainment rate from Figure 18 is multipfled by the weight fraction entrainable. 

Density. The density of the drilling fluid is adjusted using powdered high density soHds or dissolved salts to provide a hydrostatic pressure against exposed formations in excess of the pressure of the formation fluids. In addition, the hydrostatic pressure of the mud column prevents coUapse of weak formations into the borehole. Fluid densities may range from that of air to >2500 kg/m (20.8 Ib/gal). Most drilling fluids have densities >1000 kg/m (8.33 lb/gal), the density of water. The hydrostatic pressure imposed by a column of drilling fluid is expressed as follows ... 

Density Difference Between Particle and Liquid. Separation cannot take place if A6 = 0. Some mineral oils have the same density as water at room temperature. If it is heated to 80°C, the reduction of the density of water is less than that of the mineral oil, resulting ia the water becoming heavier. Therefore separation is possible. Dilution of a Hquid by a solvent, eg, molasses by water or heavy oil by naphtha, results ia lower density and lower viscosity of the Hquid. Solvent stripping takes place at a later stage. 

Density and Relative Density. Density is mass per unit volume and in SI is normally expressed as kilograms per cubic meter (density of water = 1000 kg/m or 1 g/cm ). The term specific gravity was formerly the accepted dimensionless value describing the ratio of the density of sohds and Hquids to the density of water at 4°C or for gases to the density of ak at standard conditions. The term specific gravity is being replaced by relative mass density, a more descriptive term. 

Density. Measurement of the density of water by pycnometry is the classical method (30) for estabHshing deuterium concentrations in heavy water. Very precise measurements can be made by this method, provided the sample is prepared free of suspended or dissolved impurities and the concentration of oxygen-18 in water is about 0.2 mol %. However, in nearly all heavy water manufactured since 1950 in the United States, the... 

The values for a single property of two compounds, A and B, are useless unless these values are compared at equal temperature or pressure. Then a deviation from some intermediate value can be determined. If this intermediate value is chosen to be the value of one particular substance, ie. A, the reference substance, both A and B can then be expressed as functions of the reference substance. One very simplistic example is specific gravity where the density of a compound is expressed as the actual density divided by the density of water at 4°C and water is the reference substance. 

Density is defined as the mass of a substance contained in a unit volume. In the SI system of units, the ratio of the density of a substance to the density of water at I5°C is known as its relative density, while the older term specific gravity is the ratio relative to water at 60°F. Various units of density, such as kg/m, Ib-mass/fF, and g/cm, are commonly used. In addition, molar densities, or the density divided by the molecular weight, is often specified. This section briefly discusses methods of correlation of density as a function of temperature and presents the most common accurate methods for prediction of vapor, liquid, and solid density. 

Density and Specific Gravity For binary or pseudobinary mixtures of hquids or gases or a solution of a solid or gas in a solvent, the density is a funcrion of the composition at a given temperature and pressure. Specific gravity is the ratio of the density of a noncompress-ible substance to the density of water at the same physical conditions. For nonideal solutions, empirical calibration will give the relationship between density and composition. Several types of measuring devices are described below. 

True den.sity. The true density of the solia material is usually expressed in kilograms per cubic meter (pounds per cubic foot). This, divided by the density of water, equals specific gravity. 

Caseade tests are useful in determining all aspeets of seeondary flow. For better visualization, tests have been eondueted in water easeades. The flow patterns are studied by injeeting globules of dibutyl phatalate and kerosene in a mixture equal to the density of water. The mixture is useful in traeing seeondary flow, sinee it does not eoagulate. 

Ut = Terminal settling velocity, ft/sec Fs = CoiTection factor for hindered settling p, po = Density of water or oil, Ib/ff ... 

The most common manometer fluids arc water, alcohol, and mercury. The density of water and alcohol arc quite close to each other, whereas the density of mercury is much higher. Many factors have to be considered when selecting a fluid for a manometer, including... 

Aerodynamic Diameter The aerodynamic diameter of a particle is defined as that of a sphere, whose density is 1 g cm " (cf. density of water), which settles in still air at the same velocity as the particle in question. This diameter is obtained from aerodynamic classifiers such as cascade impactors. 

Most simulations have been performed in the mieroeanonieal, eanonieal, or NPT ensemble with a fixed number of moleeules. These systems typieally require an iterative adjustment proeess until one part of the system exhibits the required properties, like, eg., the bulk density of water under ambient eonditions. Systems whieh are equilibrated earefully in sueh a fashion yield valuable insight into the physieal and, in some eases, ehemieal properties of the materials under study. However, the speeifieation of volume or pressure is at varianee with the usual experimental eonditions where eontrol over the eomposition of the interfaeial region is usually exerted through the ehemieal potential, i.e., the interfaeial system is in thermodynamie and ehemieal equilibrium with an extended bulk phase. Sueh systems are best simulated in the grand eanonieal ensemble where partiele numbers are allowed to fluetuate. Only a few simulations of aqueous interfaees have been performed to date in this ensemble, but this teehnique will undoubtedly beeome more important in the future. Partieularly the amount of solvent and/or solute in random disordered or in ordered porous media ean hardly be estimated by a judieious equilibration proeedure. Chemieal potential eontrol is mandatory for the simulation of these systems. We will eertainly see many applieations in the near future. 

Leva [40] has shown that for liquids other than water, the L must be corrected by the ratio of the density of water to that of the fluid in the system. 

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