Density of Liquids


Density of liquids is different for different types of liquids, which helps to separate them. The density of an item is defined as its mass per unit volume. It is denoted by the character D as well as the symbol ρ, “rho”. The Standard unit of density is kg/m3, which stands for kilogram per cubic metre. Density may be computed using the equation mass divided by volume. A homogeneous substance, such as ice, has identical density throughout because its particles are tightly packed collectively.

Density Definition

  • The density of a substance is described as the density of that substance in a specified region.

  • The substance's density is defined as its mass per unit volume.

  • It is an estimate of how closely matter molecules are packed collectively.

  • Depending on the intermolecular pressures engaged in packing, different substances have varying densities.

  • $\mathrm{H_2O}$ density, 1 gram/cubic centimetre, is often utilized as the reference number for estimating the density of various materials.

SI Unit of Density

  • The SI (System International) unit of density is Kg per cubic metre.

  • The density of a material is described as the connection between its mass as well as the volume it fills.

  • It illustrates how heavy an object may be at a fixed volume in qualitative parameters. Because the density of various materials varies, different materials with identical volumes would weigh differentially.

$$\mathrm{Density = Mass/Volume=\frac{g}{cm^3}=\frac{g}{ml}}$$

The Density of Some Common Liquids

Acetaldehyde18° C783 kg/m3
Acetic Acid25° C1049 kg/m3
Acetone25° C784.6 kg/m3
Beer (varies)10° C1010 kg/m3
Benzaldehyde25° C1040 kg/m3
Camelina oil15° C924 kg/m3
Cashew nut oil15° C914 kg/m3
Castor oil25° C952 kg/m3
Methane-164° C465 kg/m3
Peanut oil20° C914 kg/m3
Pentane20° C626 kg/m3

Table-1: Density of some common liquids

Application of Density of Liquids

  • There are several uses for liquid density, such as floatation, as well as sinking. Sinking plus floating of an item on top of a liquid relies on its relative density. E.g., submarines & ships. Although these are composed of iron, which has a higher density than $\mathrm{H_2 O}$, containers loaded with air are built alongside them. These containers are known as ballast containers, and by adjusting the air in them, the submarine may float on the top of the sea. For underwater explorations, the air in these containers is removed, making the submarine bulkier, thus allowing it to go to a chosen level.

  • Oil spill clean-up- Because oil has a lower density, it hovers on the top of the $\mathrm{H_2 O}$. This density differential characteristic aids in the clean-up of oil spills.

  • Purity criteria and the identification of unfamiliar liquids-When an impurity is introduced, the density varies. The type of impurity influences this shift. Its purity may be determined by correlating sample densities to standard values. Unknown fluids are similarly recognized by analysing their densities as well as comparing them to the reference densities.


Density is among the physical qualities of matter that are utilized to quantify an entity's relative weight for a fixed volume. Depending on the temperature, the density of fluids is in the intermediate stage to that of solids as well as gases for all forms of matter. It is greatest for solids plus least for gases. A liquid's density is determined by the mass-to-volume ratio.

It is an inherent feature of matter since it is independent of the quantity of matter present. It is calculated in g/l, as indicated analytically. Specific gravity is also determined for fluids, which would be the relative density of fluids compared to the density of $\mathrm{H_2 O}$ at four degrees Celsius. This proportion is utilized to calculate the floating or even sinking of items on the water's surface.


Q1. What are the variables that influence density?

Ans. The density of an entity is determined mostly by its volume, but also by mass. The mass of the entity stays constant, but the volume of the item may be raised or lowered by varying the temperature plus pressure. When the body's temperature rises, the volume rises as well, and when the temperature falls, the volume falls as well. When it comes to pressure, as the pressure rises, the volume of the body reduces, and as the pressure falls, the volume of the body rises. One could draw 2 conclusions from this, which are mentioned below −

  • Because volume plus temperature is exactly related, density is also proportionate to temperature.

  • Because volume and pressure are inversely related, density is also inversely related to pressure.

Q2. How do you calculate the density of a body?

Ans. The density of a body may be determined using the following formula −

$$\mathrm{Density = Mass/Volume}$$

The weight of the body may be calculated using a weight scale. Furthermore, employing the submersion displacement, the volume may be determined. To estimate volume, load the tank with water as well as immerse the individual completely. Following that, the level of $\mathrm{H_2 O}$ would grow, and this increase would represent the volume of the body. Therefore, by plugging the data into the above equation, one can simply compute the density.

Q3. What exactly are immiscible fluids?

Ans. Whenever two substances cannot combine to produce a homogenous mixture, this is called immiscibility, and the constituents are considered to be immiscible. As a result, fluids that cannot combine to produce a homogenous mixture are referred to as immiscible fluids. In the event of immiscible fluids, the mixture's constituents separate, with the denser element sinking as well as the less dense element rising to the top. Water, as well as oil, are the most typical types of immiscible fluids, whereas alcohol plus water are examples of miscible fluids.

Q4. What are the distinctions between viscosity as well as density?

Ans. Density is the assessment of the molecular mass of the mixture of distinct elements, whereas viscosity is the assessment of the forces between molecules, as well as molecular shapes. The viscosity of a liquid could be used to calculate friction between 2 layers. The temperature has a minimal influence on density when compared to viscosity, even though all are inversely proportionate to temperature. The connection between viscosity and temperature is generally exponential, whereas the relationship between density and temperature is typically linear.

Q5. What exactly is relative density?

Ans. The distinction between density as well as specific gravity at ambient pressure & temperature is the density of water, but this density is taken as a standard density and also the density of any other substance is computed relative towards this density. As a result, the determined density is termed specific gravity or relative density. The relative density of a material determines if it would sink or float. It also provides information on relative mass.

Updated on: 28-Apr-2023

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