Measuring Mass
Using a Triple Beam Balance
Part 1 – Parts of the Triple Beam Balance
Beams
Poises
Pan
Zero Mark
Pointer
Zeroing Knob
Part 2 – Steps to properly mass an object
I. Zeroing the Balance
1. Slide all the poises on the beam to the zero mark
2. Turn the zeroing knob (located at the left end of the beam under the pan) until the pointer
lines up with the zero mark.
3. It is wise to check the balance periodically since foreign material may accumulate on the
beam or pan and cause a slight change in position of the pointer.
4. Whenever the balance is moved, the balance should be checked and zeroed again if
necessary.
II. Massing an Object
1. Place an object on the pan of the Triple-Beam.
2. Move the poises on the beam with the largest numbers (100 gram poise) until the pointer
drops below the zeroing mark. Slide that poise back one position (make sure the arrow
points at a number and it locks into the notch).
3. Repeat the above step with the next smaller beam (10 gram poise).
4. Slide the smallest poise until the pointer aligns with the zero mark on the balance.
YOU HAVE JUST FOUND THE MASS OF THAT OBJECT. NOW:
III. Reading the Dial-O-Gram.
5. Add the following:
a. The reading from the 100 gram poise
b. The reading from the 10 gram poise
c. The 1’s , 1/10ths, and an estimate of the 1/100ths place from the small poise
SPECIAL NOTE: The mass should be given in a measurement to the nearest 0.01 grams.
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Sample Reading:
What does a can of DMD weigh?
The reading:
The 100 gram poise shows 300 g
The 10 gram poise shows 70 g
The small poise shows 3.35 g
The mass of the can of DMD = ___________
For more help on reading the Triple Beam Balance visit the following website:
http://chemistry.rutgers.edu/genchem/balance3b.html
10 gram
1.0 gram
100 gram
poise
poise
poise
Massing with the Electronic Balance:
The electronic balance must be zeroed before each item is measured
1. With the cover closed press the On/Tare button and wait for the display to read 0.000 g
and the * is displayed
2. Repeat step 1 if necessary
3. Open the cover and place the object on the pan
4. Close the cover and wait for the reading to stabilize
5. Write down the mass to the precision that the electronic balance provides and enter it in
the Accepted Value column
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