# What is Density

In this post, we learn about what is density.

## What is Density

Density of many samples is measured in labs for example in united states oil and gas industry, they define density in general way as ‘weight per unit volume’ although ‘weight per unit volume’ is not density it is ‘Specific Weight’ so density is ‘mass per unit volume’.

Density is also known as “Volumetric Mass Density”. Generally different materials have different density. Chemical element Osmium (Os having atomic number 76) is naturally occurring densest element. To simplify the comparison of densities of different materials or liquids it is needed to replace density with “relative density” as relative density is dimensionless quantity. Relative Density is also called “Specific Gravity”.

Specific gravity or relative density is the ratio of density of sample material to the density of standard material. Generally water is taken as standard material. If we take water as standard material than if we get relative density of a material is less than ‘1’ means that material floats in water. Water has highest density at 4 °C i.e. 1000Kg/m3.

Density of material depends on the temperature and pressure. Effect of temperature and pressure is very less on solid and liquid but effect of temperature and pressure is very high on gases. If we increase pressure on given material than its volume get decrease that result in increase in density, similarly If we decrease pressure on given material than its volume get increase that result in decrease in density. And in case of temperature, if we increase temperature on given material than its volume get increase that result in decrease in density, similarly if we decrease temperature on given material than its volume get decrease that result in increase in density. But their are some exceptions which do not follow these rules, one of them is water means when temperature of water decreases than it makes solid ice which float on liquid water as ice have less density than liquid water i.e. Density of ice is 916.7 Kg/m3 at 0 °C, and water has a density of 999.8 Kg/m³ at 0 °C.

### Definition of Density

Density of a material is defined as its mass per unit volume.

#### Symbol of Density

Symbol of density is ‘ρ‘ or ‘D‘ and pronounces as ‘rho‘.

#### Formula of Density

Density = Mass/Volume
or,
ρ = m/V
where,
ρ is density, m is mass and V is volume.

• When numerator (mass) is much larger than denominator (volume) in density formula, that shows the given substance has higher density, but when denominator (volume) is much larger than the numerator (mass), that shows the given substance has lower density.

#### SI Unit of Density

SI Unit of Density is Kg/m3 or g/cm3

#### Instruments used to measure Density

Hydrometer and Thermometer is used to measure the density of liquids.
 Hydrometer

 Hydrometer dip in mineral oil and engine oil to measure the Density of these samples

### Density Chart

Material
Density (Kg/m3)
Remark
Air
1.2
At sea level
Milk
1027 to 1033
At 20 oC
Honey
1420
At 20 oC
Coconut Oil
925
At 15 oC
Cotton Seed Oil
926
At 16 oC
Olive Oil
918
At 15 oC
Sunflower Oil
919
At 20 oC
Rice Bran Oil
918
At 20 oC
Groundnut Oil
913
At 20 oC
Liquid Hydrogen
70
Ice
916.7
At 0 oC
Fresh Water
1000
At 4 oC
Plastics
1175
Approx for PVC
Glycerol
1261
Also called Glycerine or Glycerin
Aluminium
2700
Chief ore of Aluminium is Bauxite
Diamond
3500
Precious stone
Zinc
7000
Zinc is found in cells throughout the body.
Iron
7870
Used since ancient times
Cobalt
8900
Found in the Earth’s crust only in chemically combined form
Nickel
8900
Silvery-white lustrous metal
copper
8940
Very high thermal and electrical conductivity
Silver
10500
Highest electrical conductivity, thermal conductivity
11340
Soft, malleable, and heavy metal
Mercury
13546
Only metallic element that is liquid at room temperature
Uranium
18800
weakly radioactive because all its isotopes are unstable
Iridium
22420
Densest naturally occurring element
Osmium
22570
Densest naturally occurring element