# Agar Cubes

**Topics:**Measurement, Diffusion, Molecular diffusion

**Pages:**2 (1128 words)

**Published:**October 30, 2014

Investigating the effect of surface area-to-volume ratio on efficiency of diffusion of cells 452628014541500right1745615Expected Graph of Length vs Efficiency 020000Expected Graph of Length vs Efficiency

Hypothesis: It is predicted that as the volume of the agar cube increases, the rate of diffusion will also increase. Rate of diffusion increases because the larger the surface area the more the surface area through which diffusion can occur. The NaOH particles will have more contact with the agar particles, thereby increasing the rate of diffusion. As the surface area-to-volume ratio decreases (cube volume increases), the rate of diffusion will also increase. However, it is predicted that as the agar cube volume increases, the efficiency will decrease. Therefore an inverse relationship is expected between the two variables. This is because within the same time limit, NaOH has to diffuse through more particles in the cube. As a result of this, in terms of total volume, less will be diffused through each time the cube length increases. Since, the aim of the lab is to investigate efficiency that is what will be graphed. Raw Data Table

Length of agar cubes /mm + 1 Length of cube not reached by NaOH (mm) + 1 10 5

20 15

30 25

40 36

50 45

Processing

1. Calculating Volume

For 30mm cube = 303 = 27000mm3

2. Calculating % efficiency: Total volume of cube-Volume of non diffused cubeTotal Volume of cube ×100 For 30mm cube: 303-253 mm303 mm × 100 = 1137527000 ×100 = 42.1 ≈ 42 because uncertainty does not have any decimals. 3. Calculating Surface Area:

Surface area: 6a2

For 30mm cube: 6(30)2 = 5400 mm2

4. Calculating Rate: Total volume of Cube-Volume of non diffused cubeTotal Time taken Volume can be found out by subtracting the length of the cube not reached by NaOH from the total length of the agar cube. For 30mm cube: 303- 2535 minutes = 113755 = 2275mm3 per minute 5. Calculating volume to surface area ratio

For 30mm cube = Surface AreaVolume...

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