Australia's Science Forum

Hello, this is for the people using the new Oxford textbooks. We are a 7-10 school, and there is one prac where they want to combine sodium iodide and lead nitrate to produce lead iodide. They already do this in small volumes dropwise to observe precipitation on dropping sheets. for this they want to use 20-30 mL of each in a beaker.

So.. according to CSIS lead nitrate should be used at less than 1% (which we do ) but lead iodide is a year 11-12, unless it is less than 1% solution which I guess it will be if we are using less than 1% lead nitrate (but it is only soluble up to .076% anyway - therefore a solid!)

Has anyone else done this prac for junior years and how did you manage it?

Bucket Chemistry! Gotta love it. There's another one somewhere where they ask us to give a kid 3 beakers with 100mLs of HCl in each, and then hand out 5cm strips off Zn, Mg and Cu! Yay! Talk about pop test! Blow the windows out on a good day, I'd think.

In short - I said NO. I handed out micro test-tubes and tiny dropper bottles. If we're only looking for precipitation, then that will do. If they want to do stoichimoetry (unlikely) then pick another reaction.

At the end of the day, who wants to dispose of that much lead anyway?

Well, I think they are doing stoichiometry. It's titled "precipitation and conservation of mass". They are weighing the beakers before and after and taking temperatures. O and it's 40 mL of each.

Same reply. No. Pick another reaction. Or do it in micro test tubes and measure the height of the precipitate and make "relative" statements, rather than quantitative ones. Well..they are quantitative this way, just differently quantitative.

Try this one instead:

http://m.learning.hccs.edu/faculty/stev ... cent-yield

or this:

http://people.chem.umass.edu/whelan/gen ... ment_4.pdf

Both of these use chemicals that are more management-friendly, environment-friendly etc.

Thanks.

Smiley, I've sent you a PM. I f you have any advice or know someone who does I'd be grateful