Tare bar

Place an empty weighing container (see p. 24) centrally on the balance pan and allow the reading to stabilize. If the object is larger than the pan, take care that no part rests on the body of the balance or the draught shield as this will invalidate the reading. Press the tare bar to bring the reading to zero. 

What if I have a Tare bar or Tare knob Why not use this to zero the balance before putting in product. That way, I don t have to subtract—-just get the weight of the product directly. Sure. Now take some of your product out of the vial to use in, say, another reaction. How much did you take What You say you already put it into the other reaction vial, and it s all set up and you can t take product out to weigh it What You say you think you ll lose too much product re-weighing it in yet another vial before you commit it to your reaction Did you record the tare of the product vial No One subtraction too many for you, huh ... 

Platform scales used in chemical plant are usually of the spring or the steel yard type, with or without a tare bar. The latter enables prior adjustment to be made for the weight of the container. Some general points of weighing technique, to ensure accuracy, are given below ... 

An HDPE sample together with aliquots of TBPB/styrene solution (0.3 mol % TBPB) were sealed in stainless-steel-high pressure vessels that were purged with C02 gas, tared, and heated to the soak temperature of 80 °C. A heated high-pressure C02 manifold was used to pressurize the vessel to 243 bar. The vessel was then weighed to determine the mass of C02 transferred and then heated for 5 h at 80 °C. The styrene in C02 concentration was 28 wt %. After this initial soaking period, the vessel was heated to 100 °C and maintained at this temperature for the desired reaction time. The vessel was then vented, refilled with nitrogen, and maintained at 100 °C for 6 h. 

A single control bar is used to switch the balance on and off, to set the display to zero, and to tare a container automatically on the pan. Since results are... 

You wiU use either an electronic balance or a mechanical single-pan balance (if you have a double-pan balance, your instructor will provide instructions on its use). The electronic balance is set to zero using the zero (tare) control bar or button before weighing an unknown object. For mechanical balances, the zero point is determined before weighing. 

The faint yellow oil 2,2 -bistrimethylstannyl-4,4 -bis-(2-ethylhexyl)-dithieno[3,2-ft 2, 3 -rf]silole (monomer 21) is added to a tared clean glass vial, which is kept under vacuum. The oil, weighing (0.510 mmol, 381.6 mg) once dry, is then diluted in 1 mL of hexanes and transferred to a dry Sehlenk flask equipped with a stirrer bar. The dilution/transfer of 21 is repeated four times so that the compound is completely transferred to the reaction Sehlenk flask, as a total of 5mL of hexanes solution. The hexane is then evaporated carefully under vacuum... 

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