density - Determination of Density Objective: The purpose...

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Objective: The purpose of this experiment is to determine the density of a substance from measurements of its mass and volume. Safety Tips: Wear safety goggles at all times in the laboratory. NOTE: Review the rules of graphing and significant figures before coming to lab. Background: Density of a Liquid A substance, whether it is a solid, liquid or gas, has a number of physical and chemical properties that can be determined experimentally and used to identify the substance. An important physical property of a substance is its density. Density is defined as the mass per unit volume of a substance and can be determined experimentally by measuring both the mass and volume of the substance. Density depends on the physical state of the substance and is independent of its size. Intensive properties DO NOT depend on size, therefore, density is an intensive property. In the metric system the following units of density are typically used: For gases: grams per liter (g/L) or grams per milliliter (g/mL) For liquids and solutions: grams per milliliter (g/mL) or grams per cubic centimeter (g/cm 3 ) For solids: grams per cubic centimeter (g/cm 3 ) Extensive properties DO depend on size, therefore, mass and volume are extensive properties. The mass is measured with a balance and has units of grams. The volume of a liquid is measured with a graduated cylinder (or pipet) and has units of milliliters (mL), liters (L), or cubic centimeters (cm 3 ). The volume of a regularly shaped solid can be determined by measuring its dimensions and then inserting those measurements into the appropriate formula. The formulas for the volumes of two regularly shaped solids are: rectangular solid: volume = length x width x height cylindrical solid: π (pi) x radius 2 x height The volume of an irregularly shaped solid can be determined by water displacement. This technique is based on the principle that any solid that does not dissolve in or react with the liquid it is placed in will displace its own volume when submerged. The solid is added to a known volume of water in a graduated cylinder and the volume of water in the graduated cylinder and the total volume of water and solid is measured (Figure 1). You must add enough solid to produce an observable change in the water level. The
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This note was uploaded on 07/29/2010 for the course SCI none taught by Professor None during the Spring '10 term at Armstrong State University.

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density - Determination of Density Objective: The purpose...

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