Rate of Diffusion Affected by the Change of Temperature

Rate of Diffusion Affected by the Change of Temperature

Introduction

When red dye chemicals are released in a colorless solvent, they spread out gradually until the color of the solution turns into red. This is an example of diffusion. Diffusion is the movement of materials from areas of high concentration to areas of low concentration until equilibrium is reached.

Osmosis is a special case of diffusion. It is the diffusion of water across a semipermeable membrane. Osmosis depends on how much water (%) there is on each side of the semipermeable membrane. The difference occurs when there are different amounts of solutes in the water on each side.

When a cell is placed into a solution, the solution can have more solutes, less solutes, or equal solutes as compared to the cell. When the solution has more solutes, the solution is said to be hypertonic. The cell shrinks in hypertonic solution. When the solution has less solute less solute but more water, it is called hypotonic. The cell expands in hypotonic solution. When the solution has equal solute with the cell, it is defined as isotonic. The cell stays without change in isotonic solution.

The rate of diffusion is unstable and various, since many different factors including size, shape, concentration, and temperature affect diffusion directly or indirectly. In this research, the effect of temperature on the rate of diffusion will be investigated. Therefore, other factors besides temperature are controlled equally on each trial.

Research Question

How does the temperature in solution affect the rate of diffusion?

Hypothesis

If the temperature of the solution is high, then the rate of diffusion will increase.

Variables

Materials

• One potato
• Cork borer
• Ruler
• Knife
• Electronic scale
• Beaker big enough to contain 120mL of salt solution
• Plain water
• Salt
• Cylinder with measures
• 12 test tubes
• Test tube holder
• Ice
• Heating device
• Thermometer
• Tissues
• Time watch

Procedure

1. Use cork borer to dig potato samples from one potato.
2. Use knife and ruler to cut 12 pieces of potato samples with same lengths and shapes.
3. Measure each piece on an electronic scale.
4. Record each mass of each piece.
5. Fill one beaker with plain water
6. Pour the salt in the water to make 5% salt solution. (5% salt solution is consisted of 5% salt and 95% water, not 5% salt and 100% water. Therefore, the mass of the salt should be controlled as  of the mass of water.)[pic 1]
7. Pour the solution in 12 test tubes. (10 ml each)
8. Put four potato samples in four different tubes.
9. Place those tubes on a test tube holder and locate it on the table with normal room temperature. (Avoid places where air conditioner is directly blowing)
10. Wait for 5 minutes.
11. Take out the potato samples and dry them carefully with tissues.
12. Measure the mass of each sample and record.
13. Pour plain water in a new beaker and put ices.
14. Locate test tubes with 10 ml salt solutions in the beaker
15. Wait until the temperature of the salt solutions become about 3.[pic 2]
16. Put the potato samples in each tube
17. Wait for 5 minutes
18. Take out the potato samples and dry them carefully with tissues.
19. Measure the mass of each sample and record.
20. Pour plain water in a new beaker.
21. Locate test tubes with 10 ml salt solutions in the beaker
22. Locate the beaker inside the heating device.
23. Wait until the temperature of the salt solutions become about 53.[pic 3]
24. Put the potato samples in each tube
25. Wait for 5 minutes
26. Take out the potato samples and dry them carefully with tissues.
27. Measure the mass of each sample and record.

Data Collection and Processing

Table 1: Raw data of the mass of the potato samples (before & after the experiment)[pic 6]