REGIONAL TECHNICIANS GROUP
Ideas & Alternatives
Boyle's Law Apparatus
An alternative design for this piece of equipment has been devised by Nick Corellas at Como Senior High School.
It consists of a pressure gauge and hose adaptor, and a 50mL syringe connected together by short lengths of plastic tubing. Standard 5mm ID polythene tubing fits the adaptor, and aquarium air-line tubing fits over the nozzle of the syringe. These two pieces of tubing will fit together to form an airtight seal. Volume and pressure can be read directly from the two components.
A suitable pressure gauge (range of 0 to 100kPa with ¼ thread) is available from AISAT Instruments 84 Kurnall Road, Welshpool (fax 9451 4808) - Part No. IMT1430 569 007. The adaptor is tapered fitting - Part No. TF 10-404
Bottles - nail varnish
Nail varnish bottles make very useful containers for individual student use e.g. for glue, varnish etc.
Click here for local suppliers.
In this experiment the students discover that CO2 is the gas in coke.
To a test tube add some lime water (calcium hydroxide). You will need a small conical flask with stopper and delivery tube. Put between 50-100ml of Fresh coke into the conical flask and stopper with delivery tube.
Place the delivery tube into the test tube of lime water you may need to gently swirl the conical flask, the CO2 bubbles through the lime water.
|
|
|
Thank you to Shaun Barton. Belmont City College. jc
Electrochemical cell - copper/magnesium/sulfuric acid.
A copper calorimeter serves as one terminal of the cell and a strip of magnesium ribbon the other. When the magnesium is dipped into dilute sulfuric acid (1M) in the calorimeter, enough current can be drawn to brightly light a 2.2volt globe. Hydrogen produced from the reaction of magnesium and the acid in this cell prevents polarisation and current may be drawn continuously.
Food trays.
Plastic food trays with compartments make excellent containers for individual experiment equipment:
Click here for local suppliers.
(Thanks to Pamela Mercy, Canning College for this contribution.)
Gas Laws Apparatus
The piece of equipment which is normally used for this investigation is the Absolute Zero Demonstration Apparatus (or Constant Volume Gas Thermometer.) As this apparatus is relatively costly, the experiment is usually performed as a teacher demonstration.
A low cost alternative piece of equipment may be constructed using a vacuum flask and the same type of pressure gauge as above (Boyle's Law) fitted to the flask as in the photograph. The gauge was fitted to the arm of the flask by means of an adaptor made from EVA tubing (described in the Ideas & Alternatives section of this website.)
A good range of readings are produced by first chilling the flask in a refrigerator before fitting the stopper and thermometer, and then immersing the flask in cold water on a hotplate. As the water heats up, direct readings of temperature and pressure may be taken.
N.B. The stopper SHOULD NOT be wired into the flask and the flask SHOULD NOT be heated over 100oC
Lamp holder for 240 volt globes.
A convenient lamp holder can be made by reversing the lamp socket in a microscope lamp:
(Contributed by Jeanette Ciesla, Canning College)
Micro-tier tray. Can be used for the precipitation & reaction experiment in the STAWA chemistry Lab Manual. rather than using spotting trays or depression tiles
| Available from Bob Wegman Greenwood SHS. |
|
jc
Meter movement demonstration
This simple piece of equipment demonstrates the magnetic effect of an electric current and can be used to simulate the meter movement of an ammeter.
A loop of heavy gauge copper wire is supported by two aluminium strips fixed to a wooden base. The top edges of the strips are grooved to keep the loop in place. A horseshoe magnet is placed so that the wire loop is suspended midway between the poles of the magnet. Small counter-weights of lead are fixed to the ends of the wire loop to assist movement.
When a current is applied to the loop (if using a power pack, set to 2volts DC) the loop moves between the poles of the magnet.
Photographic slides - converted to overhead projector transparancies.
Photographic slides supplied by the Education Department some years ago are still useful in some science courses but are no longer available. Reproducing these onto overhead transparency sheets not only preserves the slides but also makes them easier to view:
(Thanks to Pamela Mercy, Canning College for this contribution.)
Potato as an alternative culture medium for fungus and bacteria.
Peel a large potato and cut into 6mm thick slices.
Place potato slices in boiling water and boil for 1 minute.
Use sterilised tweezers to transfer each slice to a sterile petri dish and allow
to cool.
Inoculate the same way as for agar plates.
Potato is particularly good for culturing microbes from soil.
Relative conductivity apparatus.
The relative conductivity of ionic solutions can be show with this simple apparatus:
A 12volt 2.2watt light globe is connected in series with a LED, a pair of carbon electrodes and a pair of 6mm terminals, as in the circuit diagram. The components are mounted in a suitable sized bakalite or plastic lid which will fit over a 100mL beaker as in the photograph. Connecting wires can be easily soldered to copper coated carbon rods which may be purchased from welding supply stores. These rods are called gouging rods and are used in electric arc welders for cutting metal.
By connecting to 12volts AC, polarity can be ignored, the LED in the circuit rectifies the current and the resistance of the 12volt globe is sufficient to protect the LED.
Solutions under test are poured into the beaker and as the hydrogen ion concentration of the solution increases so does the intensity of the LED eg:
| distilled water | no light (or very slight glow in the LED) |
| tap water | dull glow in LED |
| ethanoic acid 0.1M | LED glows brightly |
| hydrochloric acid 0.1M | both LED and globe glow brightly |
For new lab staff who may not have a copy of the handy table
that is a quick reference to dilution of solutions.
It is old but very handy.
Example: To make up a 0.1M solution from a
stock 2M solution. (See arrows) measure 50ml of 2M stock solution, make up to 1litre
with water this will give you a 0.1M
solution.
Click here for printable copy.
Studying stomata - leaf peels.
Click here for an alternative technique.
Demonstration lung model.
A large balloon, approximately 60cm in diameter, may be purchased from fishing tackle shops and makes an excellent diaphragm for the bell jar lung model. The top 1/3 of the balloon is cut off and the balloon fitted over the base of the bell jar, the balloon grips tightly thus avoiding the necessity for tying and a knot is tied in the neck of the balloon to provide a 'handle'. Two smaller balloons attached to a glass Y-piece inserted through a rubber stopper serves as the trachea and lungs.
(Contributed by Jeanette Ciesla, Canning College)
The action of saliva on starch - another view.
The standard procedure for this experiment is to react starch solution with saliva and then test for the production of sugar.
As an alternative, add iodine solution to starch solution in two different test tubes then add artificial saliva solution to one of them. Place the tubes in a beaker of warm water (37°C).
As the starch is digested by the enzyme, the blue colour gradually disappears, whereas the solution in the tube with no enzyme remains blue.
Sound in a vacuum
The old "bell in the bell jar" method has always proved to be very difficult to set up to produce good results, mainly due to the difficulty in producing a good vacuum and the transmission of noise through metal stands and clamps.
This demonstration is quite effective using a small 12volt DC buzzer, available from electronics stores, which is sealed inside a filter flask.
The buzzer is suspended by its leads which are passed through a short length of glass tubing and sealed in place with epoxy glue. The glass tubing is inserted through a one-hole rubber stopper and placed inside a filter flask. Sound transmission is minimal through the leads of the buzzer.
When the buzzer is switched on and the flask evacuated, the sound decreases, but the effect is more dramatic when air is allowed to slowly enter the flask, the sound becoming noticeably louder (the "Nalgene" hand vacuum pump is ideal for this purpose as it is quiet in operation and also has an air inlet valve.)
Spectroscope demonstration
By attaching a spectroscope to the eyepiece of a video camera, the spectrum produced may be viewed on a television screen. The eyepiece end of the spectroscope pictured was wrapped with "velcro" so that it fitted snugly into the microscope adaptor of the flex-cam:
(Contributed by Jeanette Ciesla, Canning College)
Universal indicator charts:
It is sometimes difficult to get a chart that matches the exact pH colour of your universal indicator. Also the old dropper bottles with the pH indicator on the labels get stained and become unreadable. Here is a solution.
Gently peel the label from the universal indicator bottle and scan it to your computer, with just a small amount of editing reduce and crop the label to fit the dropper bottles .
Dropper bottles with labels that are able to be read and that match pH of the indicator.
If you use the same universal indicator you can click here to get a copy of edited labels. Covered with contact they will last for a while.
Water bath
An electric frypan makes a very efficient and cost effective waterbath:
(An excellent idea from the Canning College Technicians - thank you!)
This space is reserved for YOUR IDEA. Please send details to Eric Payne at Belmont City College.
The materials presented in the Regional Technicians Group web pages and its sub directories are provided voluntarily as a public service. The information and advice provided is made available in good faith and is derived from sources believed to be reliable and accurate at the time of release on the Internet. However, the information is provided solely on the basis that readers will be responsible for making their own assessment of the matters discussed herein, and that they should verify all relevant representations, statements and information.
Neither the State of Western Australia ("State") nor any agency or instrumentality of the State, nor any employee or agent of the State or any agency or any instrumentality of the State, nor any authors and contributors shall be responsible or liable for any loss, damage, personal injury or death howsoever caused and whether or not due to negligence arising from the use of or reliance on any information, data or advice provided in the Regional Technicians Group web pages and its sub-directories or incorporated into them by any person whosoever.
