Three different quantities
Mass measures amount of matter; volume measures space occupied. Density is mass divided by volume. One millilitre equals one cubic centimetre.
Mass, volume & density
Compare mass per unit volume.
Class notes
Open PDF →Selected pages previewed; the PDF contains the complete set.
Compare fairly
A heavier object is not necessarily denser: both mass and volume matter. Samples of the same uniform material have approximately the same density under the same conditions.
Measure the sample
Subtract container mass when measuring liquid. A fully submerged irregular solid’s displaced water volume can indicate its volume if it does not dissolve or absorb water.
Temperature can change density
For a fixed mass, expansion increases volume and lowers density. Many fluids expand when warmed, but there are exceptions: water expands when it freezes, so ice is less dense than liquid water.
Measure a mystery material
Compare blocks of different mass and volume. Use the scale and water displacement.
Change the mass of a sealed 100 mL object, then compare the surrounding fluids. Predict whether it floats and how much is submerged.
Sealed object, fixed volume 100 mL, no absorption or surface-tension effects. At equal density it can remain submerged; in real settings small differences matter. Diagram dimensions are schematic.
Investigate
On Compare, try Same Mass and Same Volume. Predict the ordering of densities before measuring.
Make the connection
Use a measured mass and volume to explain a density. The simulation uses kg/L, numerically equal to g/mL.
Use your own measurements · density
Interactive lab · change a variable
Calculate density
Change the sample mass and volume. Predict the density before checking.
A uniform sample is assumed. This calculator does not predict floating unless fluid density and object shape are also considered.
WATCH & CONNECT
Mass, Volume, and Density
Pause at an example and identify the mass, volume and units before calculating.
The Digital Classroom ExperienceOpen on YouTube →A sample has mass 90 g and volume 30 cm³.
Reveal the reasoning
Density = 90 ÷ 30 = 3 g/cm³. Include the unit and state what was measured.
Try it yourself
An empty beaker is 50 g. With 40 mL of liquid it is 110 g. Find the liquid’s density.
Give me a hint
First subtract the empty beaker’s mass; then divide by liquid volume.
Compare with a worked response
Liquid mass = 110 − 50 = 60 g. Density = 60 g ÷ 40 mL = 1.5 g/mL.
Investigate & explain
Design a measurement for a teacher-approved irregular solid using displacement. Record initial and final water levels, then use the difference as the object’s volume if it is fully submerged and does not absorb or dissolve.
How would an air bubble trapped on the object affect the measured displaced volume?
Compare your reasoning
A trapped air bubble adds to the measured displaced volume without being part of the solid. If the mass measurement is unchanged, dividing it by an overestimated volume underestimates the calculated density.
Common question: Heavier always means denser.
A large foam block can have more mass than a small steel bead and still have lower density.
Put the ideas to work
Choose an answer, then use the feedback to refine your reasoning.
BUILD FLUENCY