STUDY
AND INVESTIGATE DIFFUSION OF DIFFERENT
SUBSTANCES
What is diffusion ?
Diffusion is the net movement of anything from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in concentration. The concept of diffusion is widely used in many fields, including physics, chemistry, biology, sociology, economics, and finance.
For example -You walk into a coffee shop and immediately smell coffee Why? One reason is convection, Moving currents of air carry coffee smell particles all around the coffee shop but even without connection, the smell would still reach you eventually not by the connection but by diffusion. In diffusion, coffee particles move from the coffee machine (an area of high concentration) to the rest of the coffee shop (an area of low concentration). Making a cup of coffee also involves the diffusion of coffee particles through hot water:
What causes diffusion ?
In gases and liquids, particles move randomly from place to place. The particles collide with each other or with their container. This makes them change direction. Eventually, the particles are spread through the whole container. Diffusion happens on its own, without stirring, shaking, or wafting.
Why is diffusion useful ?
In living things, substances move in and out of cells by diffusion.
For example • Respiration produces waste carbon dioxide, causing the amount of carbon dioxide to increase in the cell. Eventually, the carbon dioxide concentration in the cell is higher than that in the surrounding blood. The carbon dioxide then diffuses out through the cell membrane and into the blood
• Water diffuses into plants through their root hair cells. The water moves from an area of high concentration (in the soil) to an area of lower concentration (in the root hair cell). This is because root hair cells are partially permeable. The diffusion of water like this is called Osmosis.
Rate of Diffusion
The Rate of diffusion, dn/dt, is the change in the number of diffusing molecules inside the cell over time. Since the net movement of diffusing molecules depends on the concentration gradient, the rate of diffusion is directly proportional to the concentration gradient (dc/dx) across the membrane. A rate is a quantity expressed per unit of time. For example, the speed of automobile is rate.Rate of diffusion= & Amount of gas passing through an area/Unit of time
Rate of diffusion depends upon the following factors: -
- temperature - As temperature increases, the Kinetic energy of the particles increases. Thus, the speed of particles also increases, which in turn increases the rate of diffusion
- Size and particle- As the size of the particle increases, the rate of diffusion decreases. This is because the particles become less mobile in the solvent
- Mass of the particle- As the mass of the particle increases, the rate of diffusion decreases; as the particle becomes less mobile.
Diffusion of
- Solid to Solid → Diffusion takes place in solids is a very slow process because the particles in solid can not move from their positions, the particles can show a few vibrations about their fixed position due to lack of moves in particles of solids.
- Solid to liquid → The process is known as the dissolution of a solid in liquid, and it takes place due to the diffusion of solids in a liquid medium. Example- Sugar in water
- Solid to Gas → The spreading out and mixing of a substance with gaseous form is the diffusion of solid to Gas. By the process of sublimation. Example -Camphor into Air, smoke automobile exhaust
- Liquid to Liquid → Diffusion example of liquid to liquid is the release of a drop of ink to water. The collision of the ink molecules with water molecules keeps diffusion from happening quickly.
- Liquid to solid → The diffusion of liquid to solid indicates like mercury is mixed with zinc metal
- Liquid to Gas → When Carbon dioxide diffuses into carbonated drinks then it shows the diffusion of Liquid to gas.
- Gas to Gas → Diffusion of gas to gas disperse easily because of kinetic energy. Nitrogen in the atmosphere, CO with oxygen, Ammonia gas in the air is examples.
- Gas to Liquid → The Carbon dioxide and oxygen gas present in air diffuses into the water and dissolves it. The aquatic examples are the underwater plants that use dissolved Carbon dioxide in water for preparing food by photosynthesis
- Gas to Solid → Deposition leads to turn gas directly to solid. When warm moist air inside a house comes into contact with a freezing window pane, water vapor changes to ice crystals.
Investigation of diffusion
Sugar particles break down and get dissolved in water.
I have stirred it to make the process fast and have used normal water.
|
Solvent |
Solute |
Time taken to diffuse |
|---|---|---|
sugar(5ml) |
Water(100ml) |
2minute 20 second |
|
Solvent |
Solute |
Time taken to diffuse |
|---|---|---|
salt(5ml) |
Water(100ml) |
1minute 20 second |
Honey diffusion in water- Solvent (honey) -1 tsp (5 ml) Solute (water) → 100 ml
I have stirred it to make the process fast and have used normal water.
|
Solvent |
Solute |
Time taken to diffuse |
|---|---|---|
honey(5ml) |
Water(100ml) |
1minute 30 second |
Solvent |
Solute |
Time taken to diffuse |
|---|---|---|
Food colour(5ml) |
Water(100ml) |
Less than 10 second |
More Examples of difusion:-
- When copper sulfate is brought in contact with water Requirements: Copper sulfate (cuso4) crystals, 100 mL beaker Procedure: Take about 2grams of copper sulfate crystals in a 100 ml beaker. Add about 50 mL of water and allow it to stand for few minutes.
- Note the development of blue color in water.
- Allow standing further till it is observed that all copper sulfate disappears Note the blue color change in water.
- Conclusion: When solids such as copper sulfate are brought in contact with liquids such as water, the intermingling of substances i.e., diffusion takes place.
- Diffusion is a property of matter which is based on the motion of its particles. Diffusion is fastest in gases and slowest in solids.
- The rate of diffusion increases by increasing the temperature of the diffusing substance. The phenomenon of diffusion tells us that the particles of matter are constantly moving.
- Light gases diffuse faster than heavy gases. Diffusion in gases is very fast.
- Diffusion in Liquid is slower than that in gases.
- Diffusion in solids is a very, very slow process. The diffusion of a solid substance into another solid substance is so slow that many people think that diffusion does not take place in solids at all.
- The rate of diffusion varies directly with temperature.
- small particles undergo diffusion more quickly than bigger particles.
Post a Comment