Top-loading balance

AccessChrom or TurboChrom data acquisition software, running on a MicroVax Balance, Analytical PM 2000, Mettler Balance, top loading, Mettler... 

Aspirator, water Balance, top loading Beaker, 250 mL Cylinder, graduated, 50 mL Dryer, hair Flask, filter, 125 mL Funnel, Buchner, 5 cm Goggles, safety Hot plate... 

Balance, top loading, with automatic tare, capable of weighing to 0.001 g, capacity of ISO g. 

Pressure values along the top of each table are differential pressures across the two cylinder ports. This is the pressure to just balance the load and not the pressure that must be produced by the system pump. There will be circuit flow losses in pressure and return lines due to oil flow and these will require additional pressure. When designing a system, be sure to allow sufficient pump pressure, about 25 per cent to 30 per cent, to supply both the cylinder and to satisfy system flow losses. 

Back e.m.f. 505 Back titration 311, 324 Balance analytical care and use, 75 constant load, 73 electronic, 73 free swinging, 73 maximum load of, 74 single pan, 73 Balance top pan, 75 tare facility, 74 Balancing method 652, 656 Bandwidth 663... 

The other option is weighing. Since low-tech glassware or disposable pipettes could continue to be used, obtaining a tare and a total weight on a top-loading balance would add only a few seconds for each sample, but inherently be much more accurate and precise than any operation involving just pipettes and graduated flasks. s... 

Bzik, T. J., Henderson, P. B., and Hobbs, J. R, Increasing the Precision and Accuracy of Top-Loading Balances Application of Experimental Design, Anal. Chem. 70, 1998, 58-63. 

Electronic analytical and top loading balances, Mettler or equivalent Sample chopper, Hobart, or equivalent... 

Balances with few such significant figures to the right of the decimal point (zero to three) are often referred to as ordinary balances or top-loading balances (precision is 100 to 1 mg). A top-loading balance is an electronic ordinary balance with a pan on the top, as shown in Figure 3.3. The electronic... 

FIGURE 3.3 Left, a top-loading balance. Right, an analytical balance. 

When a weight measurement enters directly into the calculation of a quantitative analysis result that is to be reported to four significant figures, is an ordinary top-loading balance satisfactory for this measurement Explain. 

Obtain samples of various foods and weigh approximately 1 g of each on a top-loading balance. Record and label each weight (as to the type of food) in your notebook Also in your notebook, give each an identifying number. Place each sample in a 100-mL round-bottom flask labeled with the identifying number. 

A top-loading balance is an electronic balance with the sample pan on the top. It is not enclosed, which means that it is capable of measuring only to the nearest hundredth of a gram. See Figure 3.3. 

In general, solid solutes should be weighed on weighing paper or plastic weighing boats, using an analytical or top-loading balance. Liquids are more conveniently dispensed by volumetric techniques however, this assumes that the density is known. If a small amount of a liquid is to be weighed, it should be added to a tared flask by means of a disposable Pasteur pipet with a latex bulb. The hazardous properties of all materials should be known before use and the proper safety precautions obeyed. 

Calibrated top-loading balance, preferably battery operated, with 0.01 g sensitivity... 

Place the top-loading balance on a clean even surface in a location sheltered from wind, dust, and rain. Ensure that the balance pan is level center the level bubble inside the window, if necessary. Clean the pan with the brush. 

Top loading balances show the highest accuracy (Fig. 2.10). Objects can be weighed very rapidly with these balances because the total weight, to the nearest 0.001 g, can be read directly off either an optical scale (Fig. 2.11) or a digital readout. Balances of this type are very expensive and one should be used only after the instructor has demonstrated their use. 

A calibrated weight obtained from the National Bureau of Standards had a value of 10.000 g. When it was used on a student s top loading balance, the balance showed the following readings 9.503, 9.499, 9.500. Comment on the balance s accuracy and precision. 

On a top loading balance, a beaker weighed 102.356 g. Express the quantity in kilograms and milligrams. Show your work. 

Using a single pan, triple beam balance (Centogram) or a top loading balance (if available), determine the mass of the block (3). Record the mass to the nearest 0.001 g. Calculate the density of the block (4). Repeat the measurements for a second trial. 

Balances, single pan, triple beam (or Centogram) or top-loading... 

Top loading balance, electronic, with capacity 0-200 g, precision... 

Off-center errors are problems specifically associated with top-loading balances. Placing a balance pan above the fulcrum places different torques and friction on balance pieces that do not exist when a balance pan hangs. The problem is exhibited if an object has different weight readings when moved to various locations across the surface of a top-loading balance pan. 

Fig. 2.25 Applications of the Roberval principle used with top loading balances. From The National Bureau of Standards Handbook 94, Figure 6, The Examination of Weighing Equipment by M.W. Jensen and R.W. Smith, U.S. Printing Office, 1965, p. 155. Reprinted courtesy of the national Institute of Standards and Technology, Technology Adminstration, U.S. Department of Commerce.

Roberval principle used in equal and unequal style top-loading balance designs is shown in Fig. 2.25. 

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