Wednesday . 12 December . 2018

# Some Fundamental Definitions In The Science of Chemistry - Some SI Units - Density

Some times or most times, we forget that the world, which is all around us, is very important, and many of us, don’t try to think about our world, from other angles.

Such angle that we should be thinking about the environment around us, is chemistry, if we are able to understand our environment, at the chemical level, then our lives would be so much simpler, and better to understand.

In today’s article we are going to continue our conversation on those, very important SI base units, which are used in chemistry.

If you want to calculate the density of an object, you would divide the mass of that object, by the volume of that object.

Therefore,

Density = mass ÷ volume.

If you decide, that you would like to isolate the volume or the mass, then you’ll need to use density, as a conversion factor.

As such, Mass = volume X density = volume X mass ÷ volume

The color code used here, is to mean that red, the volume was cancelled out, and mass was the result; after density was used as a conversion factor.

Volume = mass X 1 ÷ density = mass X volume ÷ mass

On the equation above, we did the same thing, for red, which means, that the mass cancelled out, and for green which means, that volume was the result of the equation, while using density as a conversion factor.

Density, is a characteristic property, of a substance under certain temperatures and pressures.

Also even though the value of volume and mass tend to change, Density also has a specific value, for each of its subjects.

A good example of extensive properties, are of those we mentioned earlier, such as volume and mass.

Mass and volume are good examples, of extensive properties, because they are dependent, on the amount of substance, which is present on the subject.

Intensive property, is one which is not, dependent on the amount of substance present in the subject.

Such is the case of density, which is also known as intensive property and it differs from volume and mass, for this reason.

Remember though, that for this information to be true, there has to be given a particular, or ideal, conditions of temperature and pressure.

The kilogram per cubic meter (kg/m3) is the SI unit of density; however, in chemistry, the g/L (g/dm3) or g/mL (g/cm3) units, are used as the typical unit given to density.

Below you will find a table with the common density of certain substances.

 Material Density (g/cm3) State of Matter hydrogen (at STP) 0.00009 gas helium (at STP) 0.000178 gas carbon monoxide (at STP) 0.00125 gas nitrogen (at STP) 0.001251 gas air (at STP) 0.001293 gas carbon dioxide (at STP) 0.001977 gas lithium 0.534 solid ethanol (grain alcohol) 0.810 liquid benzene 0.900 liquid ice 0.920 solid water at 20°C 0.998 liquid water at 4°C 1.000 liquid seawater 1.03 liquid milk 1.03 liquid coal 1.1-1.4 solid blood 1.600 liquid magnesium 1.7 solid granite 2.6-2.7 solid aluminum 2.7 solid steel 7.8 solid iron 7.8 solid copper 8.3-9.0 solid lead 11.3 solid mercury 13.6 liquid uranium 18.7 solid gold 19.3 solid platinum 21.4 solid osmium 22.6 solid iridium 22.6 solid white dwarf star 107 solid

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## Editor Corner

Hi every one, I obtained a bachelor's degree in Bioinformatics back in 2006, from Claflin University, after I received my bachelor's degree, I gained full time employment as a software engineer at a Video Relay Service company, maintaining databases and developing software for a new developed device called the VPAD.

I worked at that company for two years, then I became a web developer, and worked for a magazine for three years. After that job, I worked as a Drupal web developer, as a subcontractor for the NIH, for a year and then left the job to go back to school.