Question 1 (2 marks)
Calculation
A solid has mass 54 g and volume 20 cm³. Find density.
Show model answer / marking points
54 ÷ 20 = 2.7 g/cm³ (2).
Required Practical 17: Density | AQA GCSE Science | The Science Department
About this practical and its aim
Aim
Measure the density of regular solids, irregular solids and liquids.
Introduction
This practical has good links with mathematics so make sure that you link this in your mind. By now, you should understand density and how to calculate it, however, we very rarely get to, or need to measure it ourselves. By the end of this, you should know how to, and more importantly, understand how to measure the density of a regular shape (e.g. a metal cube), an irregular shape (e.g. a chess piece) and a liquid (e.g. cooking oil).
The science behind the practical
Density is mass per unit volume. Regular solid volumes can be calculated from dimensions; irregular solid volume can be measured by displacement.
Key things to remember
Use the correct measuring instrument, read meniscus at eye level and convert units carefully.
Equipment and apparatus
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Balance
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ruler or vernier callipers
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rectangular solids
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irregular solid
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measuring cylinder or displacement can
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water
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liquid sample
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beaker
Method: How to carry out the experiment
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Method 1: Density of a regular object
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Using a balance, find the mass (kg) of a solid block of regular shape (steel cube)
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Measure the width, height and length then calculate the volume (m3)
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Calculate the density by dividing the mass (kg) by the volume (m3).
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Method 2: Density of an irregular object
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As above, find the mass of the object using a balance and record it (kg)
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Setup a Eureka can over the edge of a sink and fill with water over the level of the spout
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Allow the water to drain
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Place a measuring cylinder underneath the spout
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Gently lower the irregular object into the Eureka can. Do not put your fingers
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The volume of water displaced is the volume of the irregular object. Read this value off the measuring cylinder
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Calculate the density as above. Ensure that you convert to the correct units: mass (kg) & volume (m3).
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Repeat for a variety of objects and materials.
Variables and fair testing
| Type of variable | What is measured or controlled? |
|---|---|
| Independent variable | Material or object measured |
| Dependent variable | Calculated density (kg/m³ or g/cm³) |
| Control variables | Equipment calibration; liquid temperature; immersion/air bubbles |
Safety and managing risks
Follow your teacher's instructions and your school's risk assessment. This page is not a substitute for a formal risk assessment.
| Hazard | Risk | Precaution |
|---|---|---|
Glass cylinders and water |
Broken glass, wet benches and slips |
Use stable vessels and clear spills immediately. |
Heavy objects |
Dropped object can injure toes or damage glass |
Lower objects gently with appropriate tools. |
Results, calculations and analysis
Recording, presenting and interpreting results
Record mass, volume and density for each material; show units and repeated measurements.
Calculations
Density = mass ÷ volume; for rectangular block V = length × width × height.
Conclusions, accuracy and evaluation
Drawing a conclusion
A substance has characteristic density at a stated temperature; results depend on measurement precision.
Evaluating the investigation
Use suitable balances/callipers, remove air bubbles during displacement and avoid parallax.
More to learn
Density conversions
1 g/cm³ = 1000 kg/m³. Check whether units on the question match the units in the answer.
Common exam mistake
For an irregular solid, measure the volume of displaced water, not just the final cylinder reading.
GCSE examination practice
Answer each question in full before opening the model answer. Check your work against the marking points and look for scientific key words.
Question 2 (3 marks)
Method
How is volume of an irregular insoluble solid measured?
Show model answer / marking points
Immerse it fully in water (1), measure water displacement (1) and treat displaced volume as object volume (1).
Question 3 (1 marks)
Evaluation
What reading error is avoided by observing the meniscus at eye level?
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Parallax error (1).
Question 4 (2 marks)
Evaluation
Suggest one improvement to make the investigation more reliable and explain why it helps.
Show model answer / marking points
Repeat measurements and calculate a mean (1), reducing the influence of random variation/anomalies (1). Alternative valid improvement specific to the experiment with explanation can gain both marks.
This page was updated on: 23rd June 2026