[lloydparlee]

Hi, Im curious if there is any safe easy experiment you can do to turn a "cloudy" or "dark" liquid clear by adding something. I'm not well read in chemistry.. any help?

[Alberto_Kravina]

You can turn a dark liquid to a clear liquid by adding an acid to a base with an indicator that has a dark color in basic solutions and a clear color in acidic solutions or visa versa.
Another possibility would be to add an acid to a coppertetrammine complex, the deep-blue color vanishes when you add an acid.
I can't think of any experiment where a cloudy solution turns clear by adding something, but If you want to make "cloudy" experiments I'd suggest to use dry ice (solid CO₂)

[Albert]

What about chemical oscillatory reactions? I love Belousov-Zhabotinsky's one! :stunned:

[constant thinker]

I just remembered the old turning water into wine trick. It's a figure of speech but it uses an indicator that turns red in either an acidic or basic solution. You just change the pH to get either clear or red. This is a lot like what Alberto_Kravina said. You can tell whoever your demonstrating this to that you have godlike powers and can make wine out of water.

Phenolphthalein might do the trick I think. I'm not sure exactly which indicator is used. I think the range for this one is 8-10. So your solution will actually stay basic.

[pantone159]

Try this:

Make a solution of starch in water.  I have some concentrated laundry starch handy that is convenient (although it is horribly contaminated with awful perfumes  ).  After diluting this a bit, I added a drop of iodine in ethanol.  (Tincture of iodine ought to work as well.)  The result is a dark blue, almost black, solution.

Then I took a small spatula of ascorbic acid (vitamin C), and dissolved this in water.  Upon adding this to the starch/iodine (with a little swirling), the dark color goes away, as the ascorbic acid reduces I2 to colorless I-.

When I did this just now, the resulting solution wasn't *perfectly* clear, it was a little bit cloudy and pinkish, I'm not sure why.  (I didn't take any care to get any amounts right, I probably had lots more starch and ascorbic acid than I needed.)  It is certainly a dramatic enough change, though.

The phenolphthalein will work too, changing from magenta to clear upon adding acid.  (Assuming you started with a basic solution.)  Thymolphthalein will do the same, but going from blue to colorless.  o-cresolphthalein supposedly will also change from red to colorless, I'm not sure how the color compares to phenolphthalein.  If you happen to have m-nitrophenol (I don't, hard to get for an individual), that changes from yellow to colorless.  With the set of indicators, you could make a change from any-color-you-like to colorless.

[pantone159]

Or try this:

Make a solution of magnesium sulfate (Epsom salt.)  To this, add enough aqueous ammonia to form a white precipitate (magnesium hydroxide).  This is your cloudy solution.  To this, add a sufficient amount of vinegar (acetic acid).  When the mixture is acidified, the Mg(OH)2 redissolves, and you get a clear solution.

[billnotgatez]

For those who are interested
Belousov-Zhabotinsky
http://en.wikipedia.org/wiki/Belousov-Zhabotinskii_reaction

[Alberto_Kravina]

Add an Alkene to a potassium permanganate solution. The deep violet color disappears to form a colorless solution