Science Is Magic – Black Water

This is a Science Experiment by Fanny, Simon and Elisabeth.

PURPOSE:

 

 To be able to turn water into a completely different colour and be able to turn it back into clear.

 

 

OBSERVATIONS: HOW DOES THIS EXPERIMENT ‘LOOK’ LIKE MAGIC?

The water goes from completely clear to dark black in a matter of a few seconds

 

 

MATERIAL LIST:

 

Chemicals

Chemical Name & Formula Amount: grams/milliliters
 Sodium Sulfite (Na2SO3)  0.5g
 Citric Acid (Na2SO3)  0.5g
 Potassium Iodate (KIO3)  0.5g
Water (H2O) 120 mL

 

Other supplies

0.25g Corn Starch  1 small glass jar
2 beakers Measuring spoons
 Mixing rods

 

PROCEDURE: (add any changes that were necessary/made)

  1. Add 120mL of water to beaker #1
  2. Add 1/16 tsp of cornstarch to beaker #1
  3. Stir the water until the cornstarch is mostly or completely dissolved
  4. Add 1/8 tsp of citric acid to beaker #1
  5. Add ⅛ tsp of sodium sulphide to beaker #1
  6. Fill the glass with 20mL of water
  7. Add ⅛ tsp of potassium iodate to the glass
  8. Stir the potassium iodate until it is mostly dissolved
  9. Pour the two liquids into beaker #2
  10.  Wait about 5-10 seconds and watch the magic happen

 

CONCLUSION:

 

At first the reaction was very slow, or would simply not happen at all.  But by some trial and error, we found that the reaction worked best when elevating the tempurature.  The hotter water sped up the reaction, as the particles were moving quicker. Where as when we used colder water, it took longer for the reaction to happen, or it would simply not happen at all, as the particles were moving much slower due to the decrease in tempurature.  Another factor that sped up the reaction was adding more Potassium Iodate there for increasing the surface area, which created a greater chance of collision.  This reaction proves the rate law, as certain factors to speed up the reaction.

 

 

SCIENTIFIC EXPLANATION:

In the first glass, the ionic compound sodium sulfite (Na2SO3) divides itself into two sodium ions (2Na) and a sulfite ion (SO3).

Na2SO3  → 2Na + SO3

This sulfite then steals one of the hydrogens from the citric acid (C6H8O7) in the mixture, creating bisulfate, HSO3.

SO3 + H  → HSO3

In the second glass, the potassium iodate (KIO3), separates into potassium ions (K) and iodate ions (IO3).

KIO3  → K + IO3

When the two glasses are mixed, a number of reactions happen. First, the iodate ions react with the bisulfite (HSO3) to produce hydrogen sulfate (HSO4). This leaves the iodide ions (I) by themselves.

IO3 + 3HSO3 → I + 3HSO4

Then the excess iodate reacts with the iodide ions and hydrogen ions to form iodine (I2) and water.

IO3 + 5I + 6H → 3I2 + 3H2O

By adding more bisulfite into the liquid, it is reduced back into iodide ions, turning the water clear again.

I2 + HSO3 + H2O →  2I + HSO4 + 2 H

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