SIMPLE DIFFUSION AND OSMOSIS

SIMPLE DIFFUSION

WHAT IS DIFFUSION Diffusion is the movement of molecules or particles from a region of high concentration to a region of low concentration OR We can say molecules or particles move from an area where there is more particles or molecules to an area where there is less

HOW DIFFUSION OCCCURS Molecules and particles are in constant random motion. This is due to the energy that they posses; this is known as KINETIC ENERGY Solids are closely packed so they vibrate and contain little kinetic energy Liquids move around to occupy the space of the container and contain more kinetic energy so they move more Gases move about freely in space and contains lots of kinetic energy so they can move faster

HOW DIFFUSION OCCURS When molecules or particles are mixed the kinetic energy they posses allows them to move about until they are evenly distributed So the amount of kinetic energy a molecule posses will determine how fast it diffuses However there are other factors that will affect the rate of diffusion or how fast diffusion occurs

MORE ON DIFFUSION Diffusion can occur with: liquids and solids (water and dye) different liquids (water and ink) different gases (gases in the air) When particles or molecules are evenly mixed no more changes occur We can compare the rate of diffusion of different substances

MORE ON DIFFUSION Diffusion occurs everywhere but can be demonstrated in the lab with different chemicals The rate of diffusion is affected by the size of the molecules and temperature The larger the molecules the slower it will move therefore smaller molecules will move faster and diffuse faster At higher temperatures particles or molecules posses more kinetic energy and therefore the higher the temperature the faster the rate of diffusion

EXAMPLES OF DIFFUSION When you smell a flower When someone sprays perfume on one side of the room and the person on the other side smells it When we add dye to water in celebrating Phagwa When making cool aid

OSMOSIS This is the movement of water particles from a region of high water concentration to a region of low water concentration through a selectively permeable membrane.

WHAT DO YOU OBSERVE IN THE PICTURE BELOW PINK = WATER PURPLE = SUGAR

Water molecules move across the selectively permeable membrane The volume in the second half increases but the concentration of the water molecules is even Water molecules are smaller The selectively permeable membrane acts as a barrier for larger molecules

IMPORTANCE OF OSMOSIS Cells get water via osmosis Osmosis occurs in all living cells and helps to regulate the amount of water in the cells Water is very important for all chemical reactions occurring in the cell. If a cell is placed in too much water it can burst If a cell is placed in a concentrated solution it can shrink and become dehydrated. Plant cells have a cell wall that prevents the cells from bursting.

COMPARING BOTH DIFFUSION AND OSMOSIS Diffusion and Osmosis is the process of moving particles from a region of high concentration to a region of low concentration Diffusion occurs with any particle Osmosis occurs ONLY with water molecules across a selectively permeable membrane Both processes are important to the human body and living things Both can be applied to many processes in science and everyday life.