Sunday, 8 January 2017

What is specific gravity and examples with diagrams.

Specific gravity is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water at its densest (4°C) for liquids; for gases it is air at room temperature (21°C). Nonetheless, the temperature and pressure must be specified for both the sample and the reference. Pressure is nearly always 1 atm (101.325 kPa). Temperatures for both sample and reference vary from industry to industry. In British beer brewing, the practice for specific gravity as specified above is to multiply it by 1000.[1] Specific gravity is commonly used in industry as a simple means of obtaining information about the concentration of solutions of various materials such as brines, hydrocarbons, sugar solutions (syrups, juices, honeys, brewers wortmust etc.) and acids

EXAMPLES:

  • Helium gas has a density of 0.164g/liter[8]It is 0.139 times as dense as air.
  • Air has a density of 1.18g/l[8]
MaterialSpecific Gravity
Balsa wood0.2
Oak wood0.75
Ethanol0.78
Water1
Table salt2.17
Aluminium2.7
Cement3.15
Iron7.87
Copper8.96
Lead11.35
Mercury13.56
Depleted uranium19.1
Gold19.3
Osmium22.59
(Samples may vary, and these figures are approximate.)
  • Urine normally has a specific gravity between 1.003 and 1.035.
  • Blood normally has a specific gravity of ~1.060.

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