USE OF THE ANALYTICAL BALANCE - METTLER DELTARANGE AE 260 (PS-5)
1. The only control is the bar in front. A gentle tap will turn on the balance and/or tare the mass. All glass doors must be closed to obtain a reproducible mass. Note that balances should be kept scrupulously clean. Use the centigram balances for masses that need not be so precise.
2. Note that the digital display will show four decimal places (0.1 mg) for masses between zero and sixty grams. Only 3 decimal places will be shown for masses greater than 60 grams.
3. Objects should be placed gently on the balance pan.
4. Only chemicals that are completely contained (e.g. in the weighing bottles) should be placed on the pan.
5. The same balance should be used when "weighing by difference."
6. Use the centigram balances for weighing objects that do not need to be weighed "analytically".
7. After
your instructor has initialed your notebook, then you are to
weigh the six objects in the box on the front lab bench and
record the weights in your laboratory notebook. Do
fingerprints affect the weights? How about humidity?
Ambient temperature? How would you "analytically weigh out
about one gram" of a solid into each of three beakers? Try
to answer these questions and include your thoughts in your
notebooks.
YOUR NOTEBOOKS ARE TO BE SIGNED AND DATED BY THE INSTRUCTOR OR A
COLLEAGUE BEFORE LEAVING THE LABORATORY!!! DO NOT KEEP LAB
RECORDS ON LOOSE SHEETS OF PAPER. YOUR NOTEBOOK IS A LEGAL
DOCUMENT.