Wednesday, 19 March 2014

Diffusion in egg white

This experiment will allow you to investigate how the rate of diffusion into egg white is affected by the concentration of the solution they are suspended in.

Equipment

Food colouring (red or black will work best)
Pipette
6 egg whites
Ice cube tray
Steamer or hot water bath
Ruler
Knife
Measuring cylinder
Water
6 beakers
Stopclock
Paper towels

Method

Distribute the egg white into the ice cube tray so that the wells are filled.
Either in a steamer or water bath (taking care not to let the water get into the wells) heat the egg white until it solidifies. Do not use a microwave as the heating is too vigorous and will result in air bubbles forming in the egg white.
Gently remove the egg white from the trays and use the ruler and knife to cut the egg white into uniform 1cm cubes - you should aim for at least 12 cubes.
Make 6 different concentrations of food colouring solution using 100ml of water and 1, 2, 3, 4, 5 and 6 ml of food colouring.
Place each solution in a different beaker and add at least two cubes of egg white.
Leave in the solution for 3 hours then remove the egg white cubes and dry the outside using the paper towels.
Carefully slice the cube in two and use the ruler to record how far the colour has penetrated into the cubes in each solution.

Risks

Steam or hot water used to solidify the egg white could cause a scald so take care to let the ice cube tray cool before handling.
Any spills should be cleared up as quickly as possible. Any breakages should also be carefully cleared up using a dustpan and brush.
Care should be taken when using the knife to make sure you do not cut yourself.


Ball bounce height vs surface material

Equipment

Squash ball
Metre stick
Clamp and stand
Different materials (e.g. carpet, lino, cork, wood, rubber)

NOTE: ideally materials should all be the same thickness.

Method

Place one material on the floor and use the clamp and stand to support the metre stick next to it.
Next drop the ball from the top of the metre stick onto the surface and record the maximum height to which the ball bounces.
Repeat this experiment at least another two times.
Change the material and carry out another three tests.

Risk Assessment

Ensure the ball does not roll away into an area where it could get underfoot and cause a fall.
When setting up the metre stick make sure it is clamped securely so it won't fall onto people carrying out the experiment.

Squash Ball bounce height vs temperature

In this experiment you can investigate how the height at which a squash ball bounces is affected by the termpaerture of the ball.

Equipment

5 squash balls of the same type
Water bath with temperature control
Thermometer
Paper towels
Tongs
Digital video camera (high speed if possible)
Metre stick with clear markings
Clamps & stands

Method

Place the squash balls into the water bath set to 20 degrees Celcius and ensure they are completely submerged.
Leave the balls in the water for at least 5 minutes to ensure the temperature of the rubber has stabilised.
Set up the metre stick so one end is on the floor using the clamp and stand to support it.
Set up the video camera so there is room to drop the balls between it and the metre stick and so that it has a clear view of the metre stick scale.
Use the tongs to remove one rubber ball and quickly blot off any excess water using a paper towel.
Start the video camera and drop the ball from level with the top of the metre stick.
Repeat with each of the remaining 4 balls.
Stop the camera and note the recording time.
Increase the temperature of the water bath by 10 degrees and replace the balls in it, again for at least 5 minutes.
Repeat a new recording of the balls being dropped.
Continue increasing the water bath temperature and recording the balls being dropped at 10 degree intervals until you reach at least 60 degrees.
Finally review the tape to record the maximum height each ball reached on its first bounce.

Risk assessment

Slips and falls may occur if the floor gets wet, this should be prevented by drying the balls carefully and by mopping up any wet areas quickly.
At higher tempertures there is a risk of scalding from the water. Tongs should always be used to remove the balls from the water bath to prevent contact with the skin. Additionally the experiment should not be run at a water bath temperature higher than 60 degrees Celcius