Australia's Science Forum

My sub chem teacher wants to do a senior prac. I remember doing it last year and can remember that we used sand, sodium chloride, and ? The prac involved me weighing the substances and adding them to a beaker and then giving them to the kids to seperate them. I know they filtered the sand and they heated to the water to get the salt but I can't remember what the third substance was or how it was seperated. Please HELP needed for next period.

We use lead shot (which the students sift out using a tea strainer) or iron filings (make sure you wrap the magnet in gladwrap or a small plastic bag first) and they put it in the mix and pull out the iron filings. Hope this helps. Debbie

yeah thats what we do for the juniors but the one I did last year was for seniors and it was another chemical that was used

Just a guess was it copper sulphate so they can evaporate it off.

Thanks guys I can't remember what it was and it is going to drive me mad but its too late now.

I agree with nickyw.... it's Copper sulfate

I may be having a blonde moment but if both the salt and copper sulfate are in solution how will you separate them

Wasn't it calcium carbonate, which can be removed using an acid?

We do that prac
But the third substance is water Duh!

We just did it, its benzoic acid, doesnt dissolve in cold water so use ice to separate, MariaC

i'm with Wendy and Ocker...

you can also use confetti and extract it by your ebonite rod showing static electricity can be used for seperation (obviously doing that step first)
rhonda

One observation that I have to make regarding this request is why was it up to the lab technician to try and remember what this prac entailed. The teacher should have provided a photocopy of the prac required including all the materials that were needed. With enough time for the lab tech to prepare the lesson which means not at the last minute.
Lyn.

Thanks everyone for your help. I finally contacted our retired chemistry teacher and he was able to help me, I have it all written down now so I won't forget it again. whats the bet the new chemistry teacher doesn't do this prac and i will never need it again.

so what was the answer???

This is too late to help you now, but we do this using a mixture of sand, salt (NaCl) and copper II chloride. Add ethanol to a sample of the mixture - this dissolves the copper II chloride. Decant the solution off (may require a couple of rinses) and leave to evaporate to reclaim the CuCl2, then add water to the remaining salt/sand mixture to dissolve the salt. Filter and evaporate the water to leave solid salt.

In the seperation course at St Marys last year we also adder Iodine to the sand, and copper sulphate, when heated it had a purple smoke.
Can not remember properly - maybe someone out there has there worksheet - mine is at home.
Hope this is of some help.

KIMMY