Australia's Science Forum

Hi all,

A teacher wants to do "Chemical gardening" with his Year 11 Chemistry class. This is the method they are using:
https://www.wikihow.com/Make-a-Chemical-Garden

They have actually already done this, however some students were away and we have now run out of the Silica gel that they used, and I am having trouble sourcing it again. We had 2 bottles of silica gel in the cupboard (not self-indicating - we have that as well). The bottle they used was table salt consistency. The other bottle was more flour-like in consistency, and this one did not work when they tried to use it. Both of these bottles are extremely old (such that I can barely read the labels), and the phone number on one for a Sydney number is only 6 digits long, so realllllly old.

I didn't think this would be a difficult thing to source, but it seems it is. The method says to use crushed silica beads, so I suppose we could buy some of the silica beads that are used in the desiccant sachets and crush them. But the bottle that we had seemed to be already crushed (but not powdered), so this would be better if we could get that.

Does anyone have any insight on where to source this?

Thanks!

Whenever we did it,we just used Sodium Silicate solution that was in the Chem store .IIRC ,ours come from Silform .

Edit : one less step in the process , but also reduces risk as no Sodium Hydroxide needed . ….. although Sodium Silicate is Corrosive anyway .

Hmmm ,this just reminds me .

Our retired Chem teacher left a gas jar full of Chemical garden in his display cabinet in his class room. He knew what it was ,and I knew what it was .

Need to let my new Labbie know whats in it

Ah! Thanks bigmack! That's so much better! I was thinking this prac was quite scary as the initial concentration of Sodium Hydroxide that you need to make (100mL, which is eventually diluted down to 500mL) is 8M . The first time the kids did it I walked into the classroom and none of them were even wearing safety glasses .

I'll get the pre-made solution in future.

Good to see you around here still .

LOL , I’m playing house husband until I can find a job .
Still pop in when I can .Miss the job and the forum .

Good to hear from you bigmack, please keep popping in

Hi,

That's easy to make, You need to combine the sodium hydroxide (NaOH) and silica beads, the Silica beads are the small sachets that comes when you buy new shoes to absorb humidity.
Thank you.
Bacteriologist

I have sodium silicate solution, it is thick and doesn't work as well as the old solution I inherited. The original was made from a powder which you added water to and dissolved under pressure. firstly I never managed to dissolve it even with a pressure cooker. Secondly the newer one i bought is too thick. Over the years we have tried all sorts of dilutions and I still cannot get the brilliant results from the old one. the metallic crystals grow, some better than others, but nowhere as good.