Australia's Science Forum

The brown stain left by KMnO4 is the reduction product MnO2 formed when the KMnO4 oxidises some organic material on the glassware for example. The best way to remove this is to reoxidise the MnO4 with acidified hydogen peroxide. Just a few drops of say 2M HCl or 1M H2SO4 in some 3-6 Volume% peroxide...

The effect of pH on enzyme activity experiment using the enzyme pepsin on egg white is a good alternative to a salive expt.

If you boil water to remove oxygen you will need to contain it so oxygen can not ingress back in ie. pour the just boiled water into a flask which you fill to the top so that when it is stoppered there is little or no air above the water while it cools. Another way is to sparge water with oxygen fre...

Scientific glassblowers score the rod deeply on one side with a small triangular file or a glass scoring tool. Don't be afraid to score hard. Then take a smaller diameter rod and melt the end in a bunsen. Push the molten blob on to the glass rod just below the score but in the line of the score. It ...

The conventional way of making iodine solution is to use potassium iodide to dissolve iodine as described by Lorrae. It forms KI3, permitting far greater concentrations of iodine to be solubilised. The KI3 is readily dissociated releasing the iodine. The iodide ion does not affect the available iodi...

Another method for Br water - 0.1M Bromine solution may be made as follows: Weigh 1.67g of potassium bromate and 6.19g potassium bromide. Add 10ml water followed by 15ml 2M H2SO4. Stir. Make up to 100ml with H2O, warm to 60degrees for a few mins in a fumehood. Seal in glass bottle. Store in refriger...

Mother
Yes, I meant zinc powder
Wombat

Spinkle area with zinc dust. Then add some 1M HCl. Puddle this around with your fingers (use gloves if you are worried by 1M HCl), rubbing the surface of the floor. If it stops fizzing add a bit more HCl. Keep it up until stain goes. You may be left with a slight residual colouring, depending how st...

Does anyone know of a supplier of moulds for making 1cm and 2cm cube shaped blocks of agar? Ice block moulds might be OK but the sides must be straight (most are sloping). Presently, I am casting 1cm and 2cm slabs, placing them on a grid mat and then cutting with a metal rule and a scalpel blade. A ...

A word of advice about storage of NaOH solutions. Caustic attacks glass! That white precipitate you see in glass caustic bottles over time is a silicate from the glass. Store your bulk solutions of caustic in polythene bottles.Polythene Stull dropper bottles are available at $40 for 50 bottles. If y...

My water supply at home is a polythene rainwater tank. The conductivity of this water is exceedingly low at 26 uS. Distilled water can vary from below 1 to 10 microSeimens. Compare this to the town water in Goulburn at 810 uS! Water of conductivity 26uS is perfectly adequate for virtually any applic...