DIFFUSION & OSMOSIS

EXPLORE LAB SCIENCE WHAT IS ?

Diffusion is the net movement of molecules from areas of high concentration to areas of low concentration of that molecule. This random movement, or Brownian motion, is the result of collisions with other molecules in the medium.

To see diffusion in action, put a drop of food coloring into a glass of and see how it behaves. GRADIENTS

The movement of particles from high to low concentration is called “moving down the concentration gradient.”

Low concentration High concentration EQUILIBRIUM

Molecules will continue to diffuse like this until they reach equilibrium, or until there are equal concentrations of that molecule throughout the whole medium. This is why the food coloring particles disperse until the water is the same color all the way through. OSMOSIS

Osmosis is a specialized type of diffusion that describes the movement of water molecules. Osmosis occurs when you have with unequal concentrations of water molecules on either side. Water molecules will diffuse across the membrane until equilibrium is reached. SEMIPERMEABLE

When you made your naked eggs, you removed their shell. Now they are surrounded by a . What is let across the membrane is determined by the size, shape, or charge of the molecule and the characteristics of the membrane’s pores. The egg membrane is only permeable water in your experiments, so all the changes you see are because of the movement of water across the membrane. NAKED EGG EXPERIMENT

If you put your naked egg in But if you put your egg in water, you probably noticed corn syrup or salt water, it that it got bigger. became shriveled. NAKED EGG EXPERIMENT

In a glass of water, the inside of the egg is going to have a lower concentration of water. H O Water is going to cross the H2O 2 membrane into the egg and make it swell.

But in corn syrup or salt water, the concentration of water is higher inside the egg. So in this case, H O water is going to leave the 2 H2O egg and make it shrivel up. BLOOD CELLS

The membrane of your blood cells acts in the same way as the egg membrane when placed in different . When placed in high water concentrations (hypotonic solutions), blood cells will accept water until they burst. In low water concentrations (hypertonic solutions), water will exit the blood until it shrivels. KIDNEYS

Your kidneys have a critical function: to filter waste products from your blood and regulate the balance of nutrients and water in your body. The functional units of the kidney, nephrons, keep the body in via diffusion and osmosis.

Osmosis is also utilized for water purification, which is crucial for the preservation of water quality and public health. is a processes used to remove impurities from water by using extreme to force it to against its concentration gradient. You can use this process in your own home to purify your drinking water. REFERENCES

• http://leavingbio.net/osmosis%20and%20diffusion.ht m • http://www.imaginationstationtoledo.org/educator /activities/how-to-make-a-naked-egg • http://kidsactivitiesblog.com/19496/egg- experiment-3 • http://www.biology-pages.info/K/Kidney.html