Density in Chemistry
Density links mass and volume and identifies substances.
About this topic
Density is mass divided by volume, ρ = m/V, usually in g/cm³ or g/mL. It is a characteristic property used to identify substances: water is 1.00 g/mL, aluminium 2.70 g/cm³ and lead 11.3 g/cm³. Objects float in a fluid if their density is lower than the fluid's.
Density depends on how closely packed the particles are and how heavy they are. Because it is a ratio, it does not depend on sample size: a drop and a bucket of pure water have the same density. It does change with temperature, since most substances expand when heated and become less dense. Water is unusual because ice is less dense than liquid water, which is why ice floats and lakes freeze from the top down, protecting life below.
Worked example: a metal block has a mass of 54.0 g and displaces 20.0 mL of water when submerged. Its density is 54.0 g divided by 20.0 mL, which is 2.70 g/mL, matching aluminium. This displacement trick lets you find the volume of irregular objects.
Applications include checking the purity of gold, ships and submarines, hot air balloons, and oil floating on water. A common confusion is thinking heavy objects always sink; a huge steel ship floats because its overall density, including the air inside, is below that of water.
Key ideas
- ρ = m/V
- Water is 1 g/mL
- Objects less dense than water float
Quick check
Use cases: where Density in Chemistry helps
- Homework: review the key idea behind Density in Chemistry before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Density in Chemistry without notes.
- Visual learning: play with the interactive lab to see how Density in Chemistry changes when you adjust its inputs.
- Teaching a friend: explain Density in Chemistry in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Density in Chemistry?
Density links mass and volume and identifies substances.
What will I learn in Density in Chemistry?
ρ = m/V. Water is 1 g/mL. Objects less dense than water float.
Is Density in Chemistry part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Density in Chemistry lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Density in Chemistry?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.