Appendix:The triple beam balance at FCCJ North

Enter the appropriate numbers in the circles to identify the parts of the balance.

1. Zero adjustment screw

2. Balance pointer

3. Index line

4. Slide weights

5. Weighing pan

Directions for weighing with the beam balance:

1. Place the slide weights in their zero notches. If the balance pointer is more than 2 millimeters off-line, use the zero adjustment screw to bring it into alignment.

2. Place the sample in the middle of the pan. Always use a container or piece of weighing paper for the sample; never place a chemical directly on the pan.

3. Move the slide weights one at a time, starting with the heaviest (giving 100-gram divisions) and then going on to the 10-gram, 1-gram, and 1/100-gram divisions. Move each of the weights in turn from higher to lower positions (200, 100, etc.), stopping at the notch where the pointer moves above the index line. Then position the smallest slide weight to align the pointer with the index line. The mass reading is the sum of the positions of all four slide

weights. Estimate to the nearest 0.001 gram.

4. After recording the reading, return the slide weights to their zero positions and be sure the balance is clean for the next user.