Lesson 2

General Rules for Using Balances

Let's go over some of the general rules for using balances.

Do not place chemicals directly on the balance pan unless they are inert (unreactive) and at room temperature. Containers, glassware, or pieces of metal can generally be put directly on the balance pan, but for most other chemicals, you need to use a container for the chemicals. (The containers, of course, are chemicals, but they are inert.) The reason for this rule is that many chemicals react with the balance pan. Some attract moisture and cause corrosion. Any residue that sticks to the pan can interfere with weighing. It could also contaminate any other chemicals weighed later in the same way. So, instead of weighing materials directly on the balance pan, always weigh the chemicals in or on something--a weighing dish, a beaker, or a piece of folded paper. When you do, remember to weigh the container first or adjust for its weight.

Be careful not to spill any chemicals on or around the balance. If you do, clean up immediately!

If for some reason your balance doesn't seem to be adjusted properly, let the instructor know. Don't just try to fix it yourself. Tell us, so we can deal with it and get it functioning properly.