Australia's Science Forum

1:1:1 sand:CuCO 3 :CaSO 4 works quite well, with about twice as much water added as plaster. It looks rock solid but crumbles easy enough. Some largish CuSO 4 .5H 2 O crystals can be mixed in as it starts to foam; so they're suspended and don't disolve too much before setting. You get nice pale-gree...

paint it with Na Oh - that should turn it pink quick! Well, unless the indicator is fading from being in a pH too far above 9. "Add more" won't cure "too much"! I always prepare by adding NaOH slowly in small portions, until just passed the color change; rather like a crude titr...

Yeeees... just after I posted. That worked. I found the web site and have been poking around. Looks good.

Dissection Connection is great! We recently purchased some of the piglets for dissection instead of the usual rats. They actually cost less than rats, the postage was really reasonable and the teacher / students found the bigger size easier to work with. They were so pleased we are ordering another...

Yes, indeed. Need more input. Is this some form of oxidation or precipitation experiment? Perhaps geology?

Banded Iron is a sedimentary rock formation, composed of alternating layers of iron oxides and shale or chert (both iron poor sedimentary rocks).

is that the nail varnish smell? he has already done that one.. wants something more nasty. OB That's the one. Ethyl ethanoate (aka. ethyl acetate) is used as a solvent in varnishes. It has a sweet but sickly scent. You can also scent it from wines, since it is the ester of ethanol and vinegar, thou...

Oh! I found it :) crush the iodine first :) Will give that a go next time! Aye. A crush disolves so much faster than the flakes -- which take something like ... forever. Crush the iodine together with the potassium iodide to aid disolution into just a small wash of water. Let it disolve before dilu...

10% Oxalic acid is fairly good at eliminating most glassware stains and such. Most.

I've also attempted lifting stuborn iron oxide using warm 5M HCl with some success. Some.

Howvever, I still have stained glassware that nothing seems to clean. Nothing. Very stubborn. Most annoying.

Thanks. I'll give it a try.

The jaw on our display skeleton has split right in half, from chin to teeth.

It's an old full sized plastic anatomical model, and a fairly clean break at a slight angle.

Is there any advice on the best/easiest way to repair it? What glue to use, etc.?

I couldn't figure out how to link from another thread, so I've updated my old post with all the tofu prac details in a new post in the thread about the effect of pH on enzyme activity. The tiny white "note page" image ( http://chemtalk.com.au/styles/prosilver/imageset/icon_post_target.gif...

Oh! Nice find. You must tell us how it goes. That sulfurous smell lingers so, and a working alternative would be appreciated.

Why didn't the students use their common sense and drop the dry ice when they could feel it burning ? Smee, c'mon! 12-yr-olds! Incompatible quantities for the most part. Trouble is I've seen kids, big and little, have ice-holding competitions, and I don't think they knew the diff between cold and r...

sunray18 wrote:So - please teach me this .. I fi buy nutrient agar, then i dont need peptone or beef stock cubes or anything like that? is that right?

That's the purpose. It's premixed. Just ... somewhat expensive.

Judy- boiling chips are not the same as calcium carbonate chips. Dont use calcium carbonate or marble chips , as boiling chips! Well, it depends. Actual "boiling chips" are often made of calcium carbonate but with a teflon coating to ensure that they are even more chemically inert. If the...

Small pieces of broken glass will also do in a pinch. (Lumps rather than shards.)

Oh, yes, it happens.

You should always use boiling chips to prevent flash boiling.

It's what they're for.

smiley wrote:Sorry guys, I resisted for as long as I could....we never suffer from plasticine becoming unworkable because of the cold. It has occasionally oozed off a windowsill like a Salvador Dali painting, but there you go.

Yes! Now to that I can relate.