Methylene Blue

Methylene blue hydrate is a different dye to regular methylene blue.  Although methylene blue is a hazardous chemical, it is used in a dilute solution as a stain in microbiology and as a redox indicator in Chemistry (for the “Blue Bottle” demonstration with glucose solution). The two chemicals are similar, but in different forms: the hydrated one […]

Iron Nails for Corrosion Experiments

Bullet Head nails from Bunnings work well 3, 4 or 5mm diameter mild steel round bar from a steel supplier. This is a softer iron alloy, so it will rust more readily. Very cheap. Black rod ties, for rebar Zinc plated, non-galvanised nails from Bunnings rust the best. I would suggest using fine steel wool, […]

Casein Powder Substitutes

Our students test dilute casein solution with Benedict’s reagent, Biuret test etc as part of a ‘carbohydrates and proteins in foods’ prac. Food Sample recipes from STAWA Human Biology Laboratory Manual exercise 19 (undated): Sample A = laundry starch or starch powder + gelatin powder + washed white sand. Sample B = glucose powder + […]

Making Lime Water

Add 2-3 spatulas of calcium hydroxide into a 500ml stock bottle and make up with distilled water.  Give it a really good mix, then allow the solids to settle.  You can filter off the solids if you prefer. Limewater is saturated calcium hydroxide Ca(OH)2. Add the (solid) calcium hydroxide to water until no more will […]

Drying Glassware Quickly

Rinse with ethanol, methylated spirits  or acetone in a well ventilated area. Works faster if glassware is hot. Use a hairdryer or incubator. Acetone or blow with N2 gas (if available) If volumetric flasks are rinsed with distilled water, they don’t need to be completely dry when making up chemicals. Place them in an oven – […]

Pollen Jelly Recipe

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Safe Handling and Storage of Radioactive Equipment

Perth Scientific and Haines supply a small cylinder that is suitable for storing small radioactive sources.    For larger radioactive sources, members reported buying a lead sheet from Bunnings which was used to line a steel toolbox. As an added precaution the radioactive sources can be  Radiation gloves are not required for the low level […]

Effect of Temperature and pH on 2 Enzymes: Amylase and Pepsin

pH Each enzyme has an optimum pH, above or below which their activity is lower. Supply students with 5 ph buffers i.e  ph 2,4,7,10 and 12 Activity was measured by transmittance  and absorbance using a Mystrica colourimeter  Temperature: All reactions are faster at a higher temperature, however the enzyme-catalyzed reactions become slower or stop if the temperature is too […]

Removing a rubber stopper stuck in a glass flask.

Possible Causes: 1.Rubber stopper fitted tightly in the flask. Flask neck might be slightly narrow for the stopper or the stopper is slightly too small for the flask. 2.Rubber stopper has hardened somewhat with age to the point where rubber attains a strong bond with glass. 3.Rubber stopper is stuck due to vacuum formed inside […]