Importance Of Laboratory Balances

813 Words 4 Pages
Objective

Familiarity with the various instruments used for making physical measurements in the laboratory is essential to the study of experimental chemistry. In this experiment, you will investigate the uses and limits of the various types of laboratory balances. (Wentworth, pg. 1)

Summary of Procedures

• All observations and data must be recorded in the notebook using ink.

• Observe the balances on the lab. If you do not know how to use them, ask the instructor for a demonstration. Make sure you are able to determine the level of precision permitted by each type of balance.

• The instructor will hand you objects whose mass are for you to determine. These objects will be labeled with a number or letter. Record the number or letter in
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Record the mass. Then determine the mass of the object by itself by using subtraction. Record your answer.

• Following the same manner, determine and record the masses of the remaining objects.

• Using a different balance, determine the masses of each object in the same manner as before. Determinations of the beaker’s mass must be to the level of precision permitted.

• Compare the masses from both balances. Did you find a difference in the masses? For future experiments, the same balance must always be used for mass determinations.

• Show the mass determination results of the objects to the instructor. The instructor will then compare your results with the true masses. If there is a major difference, ask the instructor to assist you with the use of the balances.

Pre-laboratory Questions

1.) What are the differences in meaning between mass and weight? In the laboratory, do we determine the mass or the weight of objects?

Mass is the direct measure of the amount of matter in a sample of a substance. While the difference with weight is that weight permits to know the mass determinations. It is believed that on the laboratory we will determine mass for we will be measuring the amount of matter of
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It is important to always use the same balance during the course of an experiment, so that the experiment doesn’t result erroneous. The reason it may result erroneous is because there will be a mixing of the balances and weights.

2.) What error is introduced in a mass determination if the object being weighed is warm? Why?

The error that is introduced is that the mass determination is not accurate. For the reason that the object makes the air around it to become heated. Therefore, the air then goes up and the movement may be detected causing the mass determination to not be accurate.

3.) Why should reagent chemicals never be weighed directly on the pan of the balance?

Reagent chemicals should be weighed directly into the beaker or flask in which they are to be used. Those type of chemicals should never be weighed directly on the pan, for the reason that many chemicals react with the balance pan. Therefore, by not weighing them directly to the pan we are preventing any kind of chemical reaction that can result

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