Science Diffusion Lab

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Biology Lab #1: Chemical Diffusion


To discover how the size of a cell affects the diffusion of chemicals throughout the cell.


I predict that as the cell size increases the diffusion depth and the diffusion rate will decrease. Equipment

• Eye protection
• 250 mL beaker
• Timing device
• Scoopula
• Ruler
• Scalpel
• Sodium hydroxide solution
• 3 different sized cubes of phenolphthalein agar
• Paper towels

1. Put on eye protection
2. With the scalpel cut the block of phenolphthalein agar in to a 1x1x1 cm cube (Cube A), a 2x2x2 cm cube (Cube B) and a 3x3x3 cm cube (Cube C). 3. Pour enough sodium hydroxide solution in to the beaker to cover the cells completely. 4. Place Cube A into the sodium hydroxide solution for 10 minutes. Make sure all sides of the cube come in contact with the solution. 5. After 10 minutes remove the cube with the Scoopula.

6. Carefully cut Cube A in half with the scalpel.
7. Where the sodium hydroxide diffused into the cube, the agar will have turned pink. Measure how far the colour change extends into Cube A. Record this measurement in you table. 8. Repeat steps 4-7 for Cube B and Cube C

Observations of Three Phenolphthalein Agar Cubes in Sodium Hydroxide Solution

|Cube |Surface |Volume (cm ) |Surface Area to |Diffusion Depth |Diffusion Rate | | |Area (cm ) | |Volume ratio | | | |A |6 cm |1 cm |6 |1 cm |0.1 cm/min | |B |24 cm |8 cm |3 |0.2 cm |0.02 cm/min | |C |54 cm |27 cm |2...
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