What is the most dangerous sea to swim in if you are bleeding?
Diffusion is the m____________ of a substance from an area of h_____ c_______________
to an area of l____ c_______________ until equilibrium is reached.
All substances contain particles. These particles have kinetic (movement) energy. In a
solid, particles vibrate on the spot, while in a liquid There are certain factors that affect the
rate (speed) of diffusion, for example temperature and stirring.
Sea temperatures vary. The world’s warmest seas are located near the equator, while the
coldest seas occur at the poles. Australia’s Coral Sea has a temperature of 25 – 30, the
North Sea off England has a temperature of 10-15 and the Bering Sea off Russia has a
temperature of 1 – 5.
Aim: To investigate how water temperature effects the rate of diffusion.
Materials
Tray
Thermometer
Dropper bottle of red food colouring
hot tap water
2cm ball of plasticine
ice
Stopwatch
bucket to hold water
Method
1.
2.
3.
4.
Model the plasticine into a 2-3 cm long shark.
Place the shark’s tail against the right hand end of the tray.
Fill the bucket with water from the cold tap.
Use the thermometer to take the temperature of the water. Record the temperature
in the results table.
5. Gently pour the water into the tray until water just covers the shark’s body.
6. Zero the stopwatch.
7. Drop 3 drops of red food colouring into the left hand end of the tray. Start the
stopwatch when you drop the first drop.
8. Watch the red food colouring diffuse and when it reaches your shark’s nose stop the
timer. Record the time taken to diffuse.
9. Empty the coloured water in the sink.
10.Repeat steps 4 – 9 with water from the hot tap, and then with iced cold water.