Density

**Historical Discoveries:**
– Prehistoric understanding of density
– Aristotle’s observations on density
– Archimedes’ experiment with the golden wreath
– Introduction of the term ‘Eureka’
– Galileo’s reconstruction of Archimedes’ experiment
– Archimedes coined the term ‘Eureka!’ in the bath
– Vitruvius discussed architecture in Book IX
– Galileo’s treatise La Bilancetta is available in Italian and English
– Scientific experiments on density have been ongoing since the early 20th century
– OECD guidelines detail testing procedures for chemicals

**Measurement Techniques:**
– Techniques for measuring density
– Hydrometer for liquids
– Hydrostatic balance for liquids and solids
– Understanding different types of density
– Methods for measuring homogeneous materials

**Units and Conversions:**
– SI unit: kilogram per cubic meter
– CGS unit: gram per cubic centimeter
– Commonly used units for density
– Conversion between different units
– Calculation of density based on unit cell and formula weight

**Changes in Density:**
– Density changes with pressure and temperature
– Pressure increases density while temperature changes can vary
– Liquids and solids have low compressibility and thermal expansivity
– Gases’ density is highly affected by pressure
– Ideal gas density can double with pressure or halve with temperature

**Materials and Densities:**
– Different materials have different densities
– Density affects buoyancy
– Osmium is the densest element
– Relative density compared to water
– Density changes with temperature and pressure
– Various materials have different densities
– Densities range from 0.0898 kg/m³ for hydrogen to 33,000-160,000 kg/m³ for the core of the Sun
– Densities of entities like neutron stars and white dwarf stars are also listed
– Density of water at different temperatures is provided
– Liquid water density varies with temperature
– Density of supercooled water is included
– Temperature and density values for liquid water at 1 atm pressure are listed
– Air density changes with temperature
– Density of air at 1 atm pressure for various temperatures is provided
– Specific weight and volumic quantity of air are mentioned
– Air density is influenced by standard temperature and pressure
– Air density is important in spice (oceanography)