Chem6

Experiment no. 1

Using the Analytical Balance and Electronic Balance

I. Objectives:

1. To be able to know how to use the analytical and electronic balance

2. To be able to enhance the skills in weighing.

II. Procedure:

1. After you have been instructed in the use of the balance and have become familiar with its use, obtain a set of pennies, an unknown aluminum cylinder, and a pair of tweezers from the instructor.

2. Do not handle the pennies or the cylinder with your fingers; always use tweezers. If you are using a mechanical balance, be sure to have the balance in the “off” or “complete arrest” position whenever you remove anything from or add anything to the balance pan.

3. Before you begin to determine masses, zero your analytical balance carefully. Select five pennies at random from the vial containing the pennies, and weigh each penny on your balance. Enter the data in your laboratory notebook. Keep track of the identity of each penny by placing them on labeled piece of paper.

4. Check the zero setting on your balance. Place these same five pennies on the balance pan, determine there total mass and record it.

5. Then, remove one or the pennies from the balance, obtain the mass of the remaining four and record the mass.

6. Repeat the process, removing one penny at a time. Obtain the individual masses by subtraction. This process is known as weighing by difference, which is the way nearly all mass determinations are done in the analytical laboratory.

7. Finally, check the zero on your balance, and find the mass of the unknown aluminum cylinder.

III. Materials:

1. Pennies

2. Analytical Balance

3. Aluminum cylinder

4. Tweezers or tongs

IV Data/Table:

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