# What is density?

Nov 10, 2014

Density is the mass per unit of volume of a substance.

#### Explanation:

Density measures the compactness in molecular arrangement in any substance which determines how heavy or light any substance is.

The density formula is $\text{density}$ = $\text{mass"/"volume}$. Mass units are most commonly grams or kilograms. Volume units are most commonly cubic centimeters (${\text{cm}}^{3}$), cubic meters (${\text{m}}^{3}$), or millileters (mL).

Examples of density include the following:

The density of water at $\text{4"^"o""C}$ can be written as ${\text{1.000g/cm}}^{3}$, $\text{1.000g/mL}$, ${\text{1000Kg/m}}^{3}$, and $\text{1.000kg/L}$.

The density of iron at $\text{0"^"o""C}$ is ${\text{7.874g/cm}}^{3}$ and ${\text{7874kg/m}}^{3}$.

The density of sodium metal at $\text{0"^"o""C}$ is ${\text{0.968g/cm}}^{3}$, and ${\text{968kg/m}}^{3}$.

In order to determine the density of a substance, you need to know its mass and its volume. Then divide its mass by its volume, remembering to divide the units as well.

Example
A ${\text{1.26cm}}^{3}$ sample of the element mercury has a mass of $\text{17.05g}$. What is it's density?

Solution

$\text{density}$ = $\text{mass"/"volume}$ = ${\text{17.05g"/"1.26cm}}^{3}$ =

$\text{13.5g/cm"^3}$

Here is a video example of how to solve a density problem.