Examples weight/volume percent

Weight/volume percent is often employed to indicate the composition of dilute aqueous solutions of solid reagents. For example, 5% aqueous silver nitrate often refers to a solution prepared by dissolving 5 g of silver nitrate in sufficient water to give 100 mL of solution. 

The problems with this approach are 1) without comparing the peaks to a standard or a set of standards, it is not known whether the result is a weight, volume, or mole percent, and 2) the instrument detector does not respond to all components equally. For example, not all components will have the same thermal conductivity, and thus the thermal conductivity detector will not give equal sized peaks for equal concentrations of any two components. Thus, the sum of all four peaks would be a meaningless quantity, and the size of peak B by itself would not represent the correct fraction of the total. 

To relate percent by weight to percent weight to volume, we again need to employ the density of the solution. For example, what is the percent by weight of a D5W solution The density of D5W is 1.0157 g/mL. Let s see we need to convert 5.0 g per 100 mL into grams per 100 g. That is, we need to convert the denominator from 100 mL into 100 g. Density is the quantitative relationship between mass and volume. So, let s apply the density as a conversion factor to convert the amount of solution from milliliters into grams. You will find this solution is 4.9% (w/w) glucose. 

Uniformity of lower limits on a mass basis. Concentrations of vapors and gases usually are reported in volume percent. As molecular weight increases, the lower limit usually decreases. On a mass basis, the lower limits for hydrocarbons are fairly uniform at about 45 mg/L at 0°C and 1 atm. Many alcohols and oxygen-containing compounds have higher values for example, on a mass basis, ethyl alcohol in air has a lower limit of 70 mg/L.27... 

Water absorption showed a rather complex quantitative pattern for composites of HDPE, wood flour, and talc. Evidently, the higher the plastic content and the talc content, the lower the water absorption. However, in the triple system when talc also replaced plastic, and wood fiber content increased, the relationship with water absorption was not that simple, particularly when weight and volume percents of the ingredients were considered. For example, after 4000 h of water immersion, the composition of 44% HDPE, 27% wood flour, and 27% talc (the balance was a lubricant) absorbed 6% water (w/w). A slight increase of HDPE content to 47%, with a concurrent increase of wood flour to 40% and decrease of talc content to 10% gave 11% of water absorption. A sharp decrease of HDPE content to 25%, with both a concurrent decrease of wood flour (36%) and increase in talc (36%) resulted in 13% of water absorption. Finally, a composition with 28% of HDPE, 54% of wood flour, and 14% of talc absorbed 20% of water [6-8]. 

By lowering the volume percent of resin and increasing the volume percent of the filler, the composite CTE is reduced. This is best illustrated in Figure 3.17 where an epoxy resin formulated with 15 phr of m-phenylenediamine has a CTE of 50 ppm/°C without filler. The addition of about 60% by weight of alumina, for example, lowered the CTE to about 25 ppm/°C. 

The density of chemical is the weight/volume of the chemical being fed. This can be determined from manufacturer s information or by calculation from measuring the specific gravity (Example 8-2). The solution strength in percent is obtained from manufacturer s information (or from provided specific gravity tables for each chemical see Appendix C for examples). 

Most chemical cleaning contractors calculate the concentration of chemicals in weight percent, but some use volume percent. The user must be aware of this. For example, a 10 wt% solution of HCl is equivalent to 25 vol% of the normal 30% concentrated HCl. 

U.S. regulations define this standard as foUows proof spirit shaU be held to be that alcohoHc Hquor which contains one-half its volume of alcohol of a specific gravity of 0.7939 at 15.6°C ie, the figure for proof is always twice the percent alcohol content by volume. For example, 100° proof means 50% alcohol by volume. In the United Kingdom as weU as Canada, proof spirit is such that at 10.6°C alcohol weighs exactiy twelve-thirteenths of the weight of an equal bulk of distiUed water. A proof of 87.7° indicates an alcohol concentration of 50%. A conversion factor of 1.142 can be used to change British proof to U.S. proof. 

The main purpose of magnesia addition to a limestone wet scrubbing system is to facilitate high S02 removal. For a wet scrubber that cleans flue gas from a utility coal-fired boiler, the scrubber inlet gas S02 concentration is typically about 700 ppm by volume per one weight percent sulfur in the fired coal. For sub-bituminous coal having only 0.7 weight percent sulfur content, the inlet S02 concentration is about 500 ppm, and, for example, the outlet S02 has to be less than 50 ppm to achieve 90 percent removal. In order to avoid serious inhibition of mass transfer because of S02 back-pressure, the equilibrium S02 partial pressure should be about four or more times lower than the actual S02 partial pressure in the gas. Thus, Figure 3 indicates that for this low-sulfur coal system, the scrubber inlet pH should be at least 5.5, and the outlet pH at least... 

EXAMPLE 2-6 Consider a mixture of 47.6 weight percent n-pentane and 52.4 weight percent n-heptane. Estimate the specific volume of the liquid at its bubble point at 400°F. Also estimate the specific volume of the gas at its dew point at 400°F. 

The macroscopic density of a particular specimen, determined from the weight and volume of that specimen, is usually less than, and cannot exceed, the x-ray density, because the macroscopic specimen will usually contain minute cracks and pores. The x-ray density is therefore a useful quantity to know. By comparing it to the macroscopic density of, for example, a pressed and sintered metal or ceramic compact, one can calculate the percent porosity in the compact. X-ray densities are sometimes loosely called theoretical densities they are not theoretical because they are determined experimentally. 

Examples. In a typical example, 20.0 mg of an iron carbonyl with 33.27 weight percent iron (i.e. 0.119 mmol Fe) was combined with 230 mg (0.714 mmol) iFeCbipy KPF j and 5 mL CH CN was added by vacuum transfer. Gas evolution began near 25°. After 1.5h, the solvent was removed from the solution by vacuum transfer and the noncondensible gas (CO) was Toepler pumped into a calibrated volume for pressure measurement. The average of four pressure measurements gave 0.47 mmol CO, for a CO/Fe ratio of 3.94. The iron carbonyl is thus LFe(C0)4]n where, in this case, n = 3. 

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