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Experiment # 2

Density

INTRODUCTION: The density of a substance is physical property that requires measurements of mass and volume. The ratio of the mass per unit volume is density, d and is written as (D = m/v). Using the metric system, the ratio for solids and liquids is expressed in g/mL or g/cm.

Matter expands and contracts according to temperature. For liquids and solids, the change in volume is very small, but for gases, a temperature results in a proportional change in the volume. Therefore, gas density is dependent upon temperature; for liquids and solids, the small effect on volume is often ignored.

PROCEDURE:

A. Density of Water 1. Find the mass of a 50 mL graduated cylinder. Take the mass out to the nearest hundredth of a gram. 2. Fill the cylinder to the 25 mL level with tap water and read the volume to one/two places past the decimal. 3. Find the mass of the cylinder and its contents and record.

B. Density of an Irregular Solid 1. Obtain a sample of an irregular solid that will be small enough to fit inside a 50 mL graduated cylinder and find its mass 2. Fill a 50 mL graduated cylinder to 25 mL with tap water. 3. Drop the irregular solid into the graduated cylinder. Record the new water level to one/two places past the decimal.

C. Density of a Wooden Block 1. Obtain one wooden block. 2. Determine the mass of the block and record it. 3. Determine the volume of the block by accurately measuring the length, width, and height of the block. 4. Determine the density of the wooden block.

D. Density of an unknown liquid 1. Weigh and record the mass of a clean and dry 50 mL graduated cylinder 2. Place about 10 / 15 / 20 mL of the unknown liquid 3. Determine the sum