Australia's Science Forum

Has anyone tried lead pencils? Apparently this works a treat. You shave the wood off so the flame will not burn it. Then you use the lead in the same way as nichrome wire. Better than fiddling around with spray bottles and nichrome wire. Of course this does not beat platinum wire but hey, who can af...

Unfortunately enzymes with the same name are not the same such as Amylase/Diastase. What to look for when purchasing or making up a solution is the number of units per gram that the powder has. A unit will be written like - "one unit will liberate 1.0mg of maltose from starch in 3 min at pH6.9 ...

Better still... I know that I am a non-taster so I will taste a bit and get nothing and then pass onto other people. The look on their faces when they taste the PTC after seeing me not having a reaction... priceless

We have found that to get the best results you use fresh boiled tap water. Boil the water and let it cool (or put it in ice bath to cool faster) to about 20 to 25 degrees before use. I have done data logging of the temperature rise when you have everything in a thermos flask and had a temperature ri...

Hi Lisa, What does you HOD need - the Iron(II) ion or the nitrate ion as you cannot get Iron(II) Nitrate. If the HOD wants Iron(II), you can substitute sulfate (as in Iron(II) Sulfate or Iron(II) Ammonium Sulfate) for the nitrate. You were almost there with the chlorine solution. Get the bleach and ...

We have been using porous pot for 2 things 1. broken pieces for boiling liquids 2. galvanic cells Have sourced small porous pots (75 x 35 mm) from Science Supply - I am sure there are other companies that supply the small pots. We are using the small pots now as they use a lot less chemical than the...

Aceto-orcein stain: 1. Mix 1g synthetic orcein with 25mL glacial acetic acid and 20 mL distilled water. 2. Boil for 4-5 minutes ONLY, in a conical flask with narrow neck. (a glass filter funnel can be placed in the mouth of the flask to act as a simple condenser if desired) 3. Filter the solution wh...

Hi Robyn, Your quite correct, you cannot recycle pyrex glass (and some other types of glass). The only glass that they will recyle is soda glass which is used generally for glass in a domestic siituation, unfortunately in labs its difficult to tell which is which (especially if in a hurry). The only...

Hi everyone, I read through the thread and wondered if I should put my 2 cents worth into the discussion. Sassi, I think your teacher needs some education about volumetric methods - not using any primary standards! The fumes on top of the HCl is HCl so the concentration is changing (granted - slowly...

Hi, Gram positive and Gram negative refers to the method of differentiating bacterial species into two large groups (Gram-positive and Gram-negative) based on the chemical and physical properties of their cell walls. The bacteria sample is stained using the Gram Stain method and in some types of bac...

Hi Rhonda & Rosalie,

I forgot about the alcohol and flaming - I suppose you do things often enough you do them automatically. I have found that if you use cotton wool plugs, it adds another route of contamination and thats why I use the Alfoil.

Cheers
Ross

Lada, You cannot use the vacuum pump for this purpose - the vacuum produced by the pump is to high and will suck what you are trying to filter into the flask (and maybe even the paper). Also you have to be very careful not to get water unto the pump. I know the water pumps are water wasteful but the...

Hi, One of our teachers at the school is an ex-microbiologist and he has passed on some tips about making nutrient agar plates (and one that I learnt the hard way). It may sound strange but I don't autoclave anything when making them - only when destroying the plates. 1. you cannot rush making the p...

Graeme, We use plastic droppers. What you have is a plastic bottle with a plastic "Stull" cap. To open up the dropper, just twist the top part of the cap. These are both good and bad. The good is you dont get the kids placing the wrong droppers back into the bottles and the bad is they see...

Ellice,

I agree with Judy, sounds like the mastrings. If the bacteria lawn grows, then this is most likely the culprit. The only other thing that I can think of is the mastrings have not stayed incontact with the agar.

Cheers
Ross

Hi Ellice,

Can you please clarify what you mean by "mixed success". It might be a couple of different reasons depending on what unexpected results you got. Unfortunately some of these pracs can be a little susceptible to slight variations in procedure.

Ross

Robyn Parkes of Eyepoint Instruments has retired. James Entwistle has taken over and his number is 02 9673 0012.

Cheers

Rob,

The common etchants are Ferric Chloride (about 42%) or Ammoinum Persulfate (about 15 to 20%).

The ferric chloride can be reused a few times.

The ammonium persulfate can not be reuesd or store once in solution. It also requires heating up to 75 degrees to be used.

Hope this helps

Ross

One of the best endothermic reactions is the barium hydroxide (solid) added to ammonium thiocyanate (solid). A liquid is formed, ammonia given off and any water on the outside of the reaction vessel freezes. Its a shame that it uses some nasty chemicals. A far safer endothermic reaction is using cit...

Hi Kerry, The 0-500V power supplies are not that often used in a high school environment. The main uses that I can think of is for running electrophoresis where a 100V DC voltage is required or to power a particular Teltron tube (cathode tube). If you are after a pure (regulated) DC voltage, the hig...