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Oak National Academy
Oak National Academy
Teachers
Pupils
New
New
Year 10
OCR
Higher

Diffusion and surface area to volume ratio

I can calculate the surface area, volume and surface area to volume ratio of different sized cubes and observe how long it takes for a liquid to diffuse into them.

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New
New
Year 10
OCR
Higher

Diffusion and surface area to volume ratio

I can calculate the surface area, volume and surface area to volume ratio of different sized cubes and observe how long it takes for a liquid to diffuse into them.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. The concepts of surface area, volume, and surface area to volume ratio.
  2. Calculation of the surface areas, volumes and surface area to volume ratios of cubes of different sizes.
  3. Use of coloured agar cubes of different sizes to observe time taken for acid to diffuse to the centre of each cube.
  4. Interpretation of results and explanation using ideas about surface area to volume ratio and diffusion.

Common misconception

Mistakes with the calculations of surface area or volume are common. The concepts of surface area, volume and their ratio, with the effect that changing these have on diffusion, are difficult.

Plenty of practise on how to calculate surface area and volume, and compare these as a ratio, some simplified, is included. The experiment results are used to show the impact of changing surface area, volume and width on diffusion.

Keywords

  • Surface area - The total area of the surface of an object.

  • Volume - The total space of an object.

  • surface area to volume ratio - The relationship between the surface area and the volume of a shape.

  • Diffusion - Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.

You could run the agar cubes as a demo on the side during the lesson to see their progress in real time.
Teacher tip

Equipment

Beakers; cubes of agar containing phenolphthalein indicator and 0.5M sodium carbonate; 0.1M hydrochloric acid; timer

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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Starter quiz

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6 Questions

Q1.
The area of this object is cm².
An image in a quiz
Correct Answer: 20, 19.98
Q2.
True or false? Diffusion is a passive process.
Correct answer: true
false
Q3.
What is the volume of this cube?
An image in a quiz
Correct answer: 343 cm³
343 cm²
294 cm³
294 cm²
Q4.
How many mm are in 4 m?
40
400
Correct answer: 4000
40 000
Q5.
What is the correct description of diffusion?
An image in a quiz
Net movement from a low to high concentration down a concentration gradient.
Correct answer: Net movement from a high to low concentration down a concentration gradient.
Net movement from a low to high concentration against a concentration gradient.
Net movement from a high to low concentration against a concentration gradient.
Q6.
What will happen to the particles of carbon dioxide?
An image in a quiz
Correct answer: They will move inside the leaf.
They will move out of the leaf.
They will stay where they are.

Exit quiz

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6 Questions

Q1.
The volume of this shape is cm³.
An image in a quiz
Correct Answer: 40
Q2.
A 4 cm wide cube takes 60 minutes to fully discolour. If we cut the cube into 4 new cubes each 2 cm wide, how long would each cube take to discolour?
Correct Answer: 30 minutes, 30, 30 mins
Q3.
What is the SA : V of this cube?
An image in a quiz
7 : 6
Correct answer: 6 : 7
8 : 7
7 : 8
Q4.
What is the relationship between the width of a cube and the surface area to volume ratio?
As the width of a cube doubles, the surface area to volume ratio also doubles.
As the width of a cube doubles, the surface area to volume ratio quadruples.
Correct answer: As the width of a cube doubles, the surface area to volume ratio halves.
As the width of a cube doubles, the surface area to volume ratio triples.
Q5.
As the SA : V increases, the time taken for a substance to diffuse will ...
Correct Answer: decrease, decreases, reduce, lessen, be shorter
Q6.
Which organism has the smallest SA : V?
Correct answer: cow
mouse
human
ant

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