Using a balance
Often times mass is a critical measurement in an experiment, so it is important to employ good practice when using a balance.
- Receptacle optional
- Balances (or scales) come in many varieties. The most common are the triple beam balance, the top-pan electric balance, and the analyical electric balance.
- A receptacle is needed for all non-solid samples, and even for solids that don't hold together (powder, ice, etc.)
- Clear the balance pan of any debris. Make sure it is clean.
- A triple beam balance requires an important calibration. Starting with all three riders on 0, dial the zero knob until the arrow stays centered on the zero meter.
- If you are using some kind of receptacle, you must first record its mass so that you may subtract it out later. If you are using an electronic balance, most have a "Tare" button that will do this automatically (see below).
- Place the object to be weighed onto the pan.
- An electrical balance will produce a digital readout of the weight. Record and you are finished.
- For the triple beam balance, you must slide each of the riders, starting with the most significant (see significant figures), until it tips the scale, then go back one notch and move on.
- Once you get the sides balanced, read each of the riders to record your final measurement. Some examples are given here:
- As you can see, the riders must be clearly on a number and not sitting in between.