Australia's Science Forum

I am wondering what clever ideas anyone has come up with for "Separation of mixtures" the prac suggests things like sand, salt, iron filings.

I need one thats NOT sand /salt / iron filings, or at least not only those.

What has worked, or not worked well for you guys?

You could use bigger things like lentils, with salt and water.

We have also done water, flour and salt.

Perhaps you could substitute copper sulfate for the salt to make it a bit more interesting? Just make sure heating stops BEFORE the water is all evaporated.

Our head teacher likes adding carbon powder to copper sulfate making a black solution that is then filtered.

You can then go the step further and separate the copper sulfate by distillation.

Here we have tin can distillation set ups for juniors.

The can has had a hole made in the bottom and a glass rod put through it. This has been secured by silicon roof sealant. Rubber tubing has been connected to that glass rod and at the other end is another small piece of glass tubing through a rubber bung that fits into a conical flask.

The fluid to be distilled is put into the conical flask and heated, the tin can is filled with an ice slurry. It works rather well.
Most common thing distilled are tea, salt water and copper sulfate. I really dislike it when they try and get oil out of gum leaves as it makes a horrible mess in the conical flask which I then have to clean.
I made them about 5 years ago and they are still working, I have had to add to the sealant on a couple.

Wendy

Not sure if these fit exactly but...

We make a slurry of mangrove mud (i.e. very fine particles) and settle one, for decanting, and add alum to some, to form clumps of solid that settle faster, then decant.

A fun one is to put a cup of Nutri-Grain in a ziplock, smash it to dust, and add water to make Nutri-Grain "soup". Then wrap glad wrap around a powerful magnet and swish it through the soup. You will get little granules of iron powder on your magnet. It is, of course, possible to dry out the slush after. This prac usually engenders discussion on choosing a method of separation may depend on what you wish to retrieve!

Oh yeah, and depending on humidity etc, you can also add in little bits of torn up paper, and separate them using static electricity.

great ideas! I will definately be suggesting these.
also any ideas for a DRY mix?

I add small pieces of styrofoam to my sand/salt/iron filings mix. You could also add talcum powder.

Ev

maybe lentils, sand and paper? (I like that paper idea, smiley!) You could probably just empty out a hole punch and they'd be about a good size

I am glad that I asked .. these are all really clever ideas. Wondering how you can separate the talcum powder Ev?

We at times have added rice and polystyrene balls

Wendy

BTW - what does the black dot mean on the little icon bizzo?

Do you mean the one on the left when the topic headings are displayed? It means you have made a comment in that thread

You can centrifuge to collect the talcum powder

Ah, that makes sense Av

We use beach sand to find % CaCO3(as shells) using HCl and filter sand off. CaCO3 would have dissolved in HCl and clean sand is dried and weight to work out loss of weight = CaCO3

I shoulkd have thought of that beach sand one! ...as I acid wash my sand , and then rinse & dry.....for other experiments..
good one