Specific gravity or relative density is the ratio of the density of a substance to the density of a given reference material. Specific gravity usually means relative density with respect to water. Temperature and pressure must be specified for both the sample and the reference. The following formula is used- Specific gravity= density of sample/density of same volume of water. Specific gravity is commonly used as a simple means of obtaining information about the concentration of solutions of various materials. Specific gravity is useful in the identification of minerals because it does not require the direct determination of volume. The determination of density for some minerals is difficult because of the irregular shapes of many samples. Definitions:
Rocks are solid substances composed of minerals.
Elements are composed of one type of atom.
Salts are composed of a metal and a nonmetal. The arrangement of atoms is highly ordered into crystals. •
Minerals may be elements or salts that occur naturally and are formed in ordered arrangements that are called crystals. Procedure for part A:
Prepare data tables to record findings.
Obtain set of metals labeled A-D
Hold one sample in your hand and heft it up and down, continue with the rest of the samples. •
Record which samples felt heavier in your hand. The objects that feel heavier for the same size have a higher specific gravity. •
Order the objects in terms of increasing specific gravity.
2nd to lightest
Procedure part B: Specific gravity of liquids.
Prepare table to collect data. Gather mass, volume, density and specific gravity for each liquid sample. •
Pipet samples of each of the four liquids (one being water) we will be examining into a test tube. •
Pipet 5mL of each liquid one at a time and place in weighing boat on balance. Record the volume and mass of each. •
Calculate the density of each using the formula:...
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