SOLIDS: Mass, Volume and Density Measurements
Review Sections 1.4 - 1.6 in your textbook (Chemistry: The Central Science, 9th Ed. , Brown, LeMay, Bursten, & Burdge)
This experiment will introduce you to a very important concept in science, especially chemistry: DENSITY. Density is the relationship between the mass of an object and the volume which it occupies. Solid substances generally have the greatest density, normally in the range of 1 - 25 g/cm3. Most liquids have densities between 0.5 - 5 g/mL, while the density of most gases under normal conditions of pressure and temperature is less than 5 g/L.
The density of a substance is a valuable tool in determining the identity of a substance.
The laboratory techniques which you will perform are provided as two exercises, each of which you should be able to complete in 30 - 45 minutes. It is not necessary that you do the two exercises in order as they appear in the laboratory manual, but you must complete both exercises during the laboratory period.
Each experiment for CHEM 1411 is written for students to work with one, two, or three partners. This experiment requires groups of three or four. Please do not work alone unless otherwise instructed.
You will record your measurements and results in the Data Tables as Trial 1. Your lab partners’ measurements and results are recorded as Trials 2, 3, and 4.
In Exercise 1, you will determine the density of a solid of regular geometric shape, and identify the composition of the solid by comparing the density with reported values. In Exercise 2, you will determine the density of pennies by water displacement.
Density of A Regular Solid
Electronic balances, beakers, regular-shaped solids, vernier calipers Safety Equipment:
In this exercise you will:
learn to operate the electronic balance properly to measure the mass of an object. 2.
learn how to read a vernier caliper
calculate volumes and densities from measurements of mass and distances
provide answers to the proper number of significant digits
The electronic balances are very sensitive to bumps and moves, etc. DO NOT MOVE OR UNPLUG THE ELECTRONIC BALANCES. ONLY YOUR INSTRUCTOR MAY MOVE OR UNPLUG THE BALANCES.
Obtain a vernier caliper and a regular-shaped solid (bar, cylinder, or sphere) from the cart at the front of the laboratory. Record the number or letter of the solid on your Data Sheet.
Measure the mass of the cylinder on an electronic balance to the nearest 0.001 gram.
Place an empty 50- or 100-mL beaker on the balance pan. Press the "Tare" button until the digital display reads "0.000 g".
Place the solid inside the beaker. Record the mass of the solid directly from the digital display on the Data Sheet.
Pass the solid to one of your partners, who will weigh the solid on a different balance.
Repeat this process until each partner has weighed the solid.
Determine the average mass from the measurements and record this value on the Data Sheet.
Each member of the group will perform the following steps with a different vernier caliper.
Place the solid between the teeth of the vernier caliper, and record the measurement of one dimension (length, diameter, etc.) to 0.01 cm in the Data Table under Trial 1.
Find the zero mark on the sliding scale. The first two digits are found on the fixed scale above.
In the drawing, the "0" on the sliding scale is between 3.3 and 3.4 on the fixed scale.
Find the line on the sliding scale which is aligned with a line of the fixed scale. In the drawing, this is the third line past the "0".
The measurement is therefore 3.33 cm.
Rotate the solid to measure a second dimension in the same manner. Measure the height of the cylinder to the nearest 0.1 mm....
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