Taring is a very convenient method of weighing out chemicals, one you will probably use quite a lot.On the protection ring, TW is tare weight, in pounds. If a substance is now added to the beaker, just the mass of the substance is displayed. Zeroes should appear on the display (the mass of the beaker minus the mass of the same beaker should equal zero). A beaker is placed on the balance pan and the tare button pushed. When a balance is tared with an object on the balance pan, the weight of the object will be automatically subtracted from every reading until the balance is re-tared or zeroed. However, it is always good practice to zero the balance when you begin to be certain it is working correctly.īy taring a balance the process of weighing by difference is done automatically. When weighing by difference an exact zeroing of the balance is not required because any error in initial reading will cancel when subtraction of the readings occurs. (mass of container + substance) - (mass of container + substance after removal) = The mass of substance taken is determined by subtracting the second reading from the first. The substance to be used is removed from the container and the container weighed again. (mass of paper + substance) - (mass of paper) = (mass of substance)Ī container holding the substance of interest is placed on the balance and weighed. The mass of the substance is determined by subtracting the first reading from the second. The substance to be weighed out is then placed on the weighing paper and weighed. These measurements can be taken in one of two ways:Ī clean piece of weighing paper is placed on the balance and weighed. Weighing by difference requires that two measurements be taken. Weighing directly requires that the balance be carefully zeroed (reads zero with nothing on the balance pan) in order to obtain accurate results. Never add chemicals to a container or piece of weighing paper while it is on the balance.Ĭlean up any spills around the balance immediately.ĭirect weighing means that an object is placed directly on a balance and the mass read. Always use a piece of weighing paper to protect it. In order to protect the balances and ensure accurate results, a number of rules should be followed:Īlways check that the balance is level before using it. If this is not the case at your school, you will need to consult your instructor to obtain directions on how to use your balances. Most balances in use now are electronic balances. While there are a great variety of balance types, they are all expensive and delicate instruments that need to be treated with respect. The measurement of mass in the laboratory is performed using balances.
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