Mass-volume calculations

With regard to accompanying compounds, a product can be obtained in 99.5% purity by preparative HPLC. Its concentration in the eluate is 5 mg ml The content of non-volatile impurities in the mobile phase is 0.002% (mass/ volume). Calculate the purity of the isolated product after the removal of the solvent. 

The facility wastewater monitoring program does not determine the concentration of lead and lead compounds in the scrubber discharge water, and releases to the surface impoundment (releases to land) must be calculated using mate-riai balance information. These releases to land are determined from the amount of lead removed by the scrubber (using the efficiency data provided by the scrubber manufacturer). The volume of the scrubber blowdown Is found to be 1,500 pounds per year. Enter the estimate of the amount of lead and lead compounds released to surface Impoundments in the space provided in Part III, Section 5.5.3 of the form. Because releases of lead to the surface Impoundment are greater than 999 pounds per year, you must enter the actual calculated amount in column A.2 of Section 5.5.1. The basis for the estimate of releases to the surface impoundment, entered in column B of Section 5, is mass balance calculations (code C). 

Capture efficiency can also be measured by first estimating workspace emission rates and local exhaust emissions. The local exhaust emission rate equals the duct concentration (mass/volume) multiplied by the duct flow rate (volume/time). The workspace emission rates can be calculated using appropriate mass balance models and measured ventilation rates and workspace concentrations. Capture efficiency is the ratio of duct emission rate to total emission rate (duct plus workspace). ... 

During an experiment, a chemist may measure physical quantities such as mass, volume, and temperature. Usually the chemist seeks information that is related to the measured quantities but must be found by doing calculations. In later chapters we develop and use equations that relate measured physical quantities to important chemical properties. Calculations are an essential part of all of chemistry therefore, they play important roles in much of general chemistry. The physical property of density illustrates how to apply an equation to calculations. 

This is a straightforward calculation. We have mass, volume, temperature, and osmotic pressure. We use Equation to calculate the molar mass. 

Because we know we are dealing with a buffer solution made from a specific conjugate acid-base pair, we can work directly with the buffer equation. We need to calculate the ratio of concentrations of conjugate base and acid that will produce a buffer solution of the desired pH. Then we use mole-mass-volume relationships to translate the ratio into actual quantities. 

In chemistry lab, a smdent was instructed to find the density of a rectangular piece of aluminum. After careful measurement, he recorded a mass of 31.44 g and a volume of 11.7 cm. Using the formula density = mass volume and a calculator, his answer was 2.6871794 g/cm. Which of these is the correct answer to report for the density of the aluminum ... 

Measurements include initial and final masses, and initial and final volumes. Calculations may include the difference between the initial and final values. Using the formula mass and the mass in grams, moles may be calculated. Moles may also be calculated from the volume of a solution and its molarity. 

Solution concentration may be expressed as a percentage, which is the amount of solute dissolved per 100 units of solvent. It may be expressed as mass %, mass/volume %, or volume/volume %. Know how to calculate the appropriate percentage concentration for a solution. 

Calculate the molcuity and the mass-volume percent solution obtained by dissolving 102.9 g H3PO4 into 642 mL final volume of solution. Be sure to use proper units. (Hint 642 mL = 0.642 L)... 

Next, calculate the mass-volume percent solution ... 

In estimating the bulk compositions of the other terrestrial planets, there are not nearly so many constraints. Determination of a planet s mass (obtained from its gravitational effect on the orbits of moons or nearby spacecraft) and volume (calculated from its diameter as measured by telescopes) enables the calculation of its mean density. A meaningful comparison of planet mean densities requires that we correct for the effects of self-compression due... 

The top-down approach is often used when there are method validation data from properly conducted interlaboratory studies, and when the laboratory using reproducibility as the measurement uncertainty can demonstrate that such data are applicable to its operations. Chapter 5 describes these types of studies in greater detail. In assigning the reproducibility standard deviation, sR, to the measurement uncertainty from method validation of a standard method, it is assumed that usual laboratory variables (mass, volume, temperature, times, pH) are within normal limits (e.g., 2°C for temperature, 5% for timing of steps, 0.05 for pH). Clause 5.4.6.2 in ISO/ 17025 (ISO/IEC 2005) reads, In those cases where a well-recognized test method specifies limits to the values of the major sources of uncertainty of measurement and specifies the form of presentation of the calculated results, the laboratory is considered to have satisfied this clause by following the test method and reporting instructions. ... 

Spreadsheet 6.1. Data from 10 fill-and-weigh experiments of a 10-mL pipette. The masses have been converted to volumes, and the uncertainty calculation assumes the components of weighing and the volume calculation are negligible. 

Bulk density of soil is the soil weight per unit volume, including water and voids. It is used in converting weight to volume in the mass balance calculations. 

You need to calculate the concentration of the solution, in grams of solute dissolved in 100 mL of solution. Then you need to express this concentration as a mass/volume percent. 

To calculate the properties of each gas in a mixture of gases To calculate molar masses from mass data along with pressure, volume, temperature data, and to use the molar masses thus calculated to enable calculation of molecular formulas from empirical formulas... 

In the metric system lengths are calculated in meters, masses are calculated in grams, and volumes are calculated in liters. The prefix of each unit is very important. You should be familiar with the following prefixes ... 

When data on airborne levels are available only in terms of mass/volume (e.g., mg/m ), it is not possible to accurately convert these to units of PCM fibers/mL, because the ratio between mass and fiber number depends on fiber type and size distribution and because of the measuring technique employed. For the purposes of making rough calculations when a more accurate conversion factor is not available, it has been assumed that a concentration of 1 mg/m in air is equal to 33 PCM fimL (EPA 1986a). 

Fill Ratio h/d can be calculated from a powder weight, granulating liquid density (1000 kg/m for water), rate of liquid addition, time interval for liquid addition, and bowl volume Vb- The calculations are performed using the idea that the fill ratio h/d (wet mass height to blade diameter) is proportional to V/Ub, and wet mass volume V can be computed as... 

Figure 2 shows a few of the tanks used to store the millons of metric tons of ammonia made each year in the United States. Stoichiometric calculations are used to determine how much of the reactants are needed and how much product is expected. However, the calculations do not start and end with moles. Instead, other units, such as liters or grams, are used. Mass, volume, or number of particles can all be used as the starting and ending quantities of stoichiometry problems. Of course, the key to each of these problems is the mole ratio. 

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