Why if you dissolve cobalt chloride solution in distilled water and then pour acetone in it, the bottom part of the graduated cylinder is red and the top part is blue?

What do you mean by it has one color with water of crystallization?

CoCl2*6H2O is a purple solid.

I'm told it has something to do with Le Chatelier's principle and the equilibrium shifting to the right and hydrogen bonding, but I still don't understand.

CoCl2 is one of those salts that have one color with water of crystallization and another when it has no water of crystallization.
CoCl2*6H2O is pink (or red?)
CoCl2 is blue.
I'll let you think that through.

If you add Cobalt(II) chloride x. 6H2O to water, it dissolves to give Chloride ions and CobaltII ions in solution. CobaltII ions are red in water. That makes the bottom red. Now in the top (acetone has less density) the water is squeezed out, and the CoCL2 is blue in that solution.

There is no hydrogen bonding in the acetone, so the water stays in the bottom.

So there is cobalt and water on the bottom and CoCl2 and acetone on the top?

Am I mixed up on my colors? I thought the hydrated form (CoCl2*6H2O) was pink/red and the anhydrous form was blue/purple. At any rate, in the two solvents you have one form in one solvent and the other form in the other solvent. Did you have two layers?

Yeah, I had two layers. No, CoCl2*6H2O is purple. I don't really know what the anydrous stuff is. I'm pretty sure we didn't use that.

The following is a quote from The Merck Index, 12th edition, 1996.

"Cobaltous chloride. Pale-blue hydroscopic leaflets; colorless in very thin layers; turns pink on exposure to moist air."
"Hexahydrate, monoclinic crystals. Structure is reported to be [CoCl2(H2O)4].2H2O. Pink to red, slightly deliquescent, monoclinic prismatic crystals. On heating loses 4H2O at 52-56o forming the dihydrate, violet or blue crystals, stable unless exposed directly to moisture. Loses another H2O by 100o, giving the monohydrate, violet, hydroscopic, amorphorous solid or needles. Remaining water lost at 120-140o. The aq soln is pink to red but turns blue when heated or when HCl or H2SO4 is added."
So it has a bunch of colors, depending upon the amount of water the anhydrous crystal has taken up.

Umm, okay, umm, could you tell me what's on the top and what's on the bottom? Was I right?

In bottom part of the solution Co(II) ion is hydrated, therefore it has pink color. When you add acetone on it some part of Co(II) ions diffuse to acetone, loosing its water of hydration. Therefore color at the top of cylinder is blue.

  1. 👍 1
  2. 👎 0
  3. 👁 1,308
asked by Lydia
  1. we had a lab session. when I added commercial acetone to cobalt chloride solution the system remained pink. it actually turned to a lighter pink color. why didn't it turned blue as its supposed to?

    1. 👍 0
    2. 👎 0
    posted by Abeer
  2. Try adding more acetone... at least the same volume of the original solution or more... keep adding it and eventually you will see the top blue layer

    1. 👍 0
    2. 👎 0
    posted by Nicole

Respond to this Question

First Name

Your Response

Similar Questions

  1. Science

    . To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find the percent concentration at this temperature. 3. A solution of acetone contains 20 ml of acetone in 480 ml of water. Calculate

    asked by Harsha on January 25, 2015
  2. chemistry

    Cobalt Chloride forms pink crystals.When they are heated,water is evolved and they turn blue. .Explain how we could use Cobalt Chloride as a test for water??

    asked by qurat-ul-ain on May 14, 2016
  3. chemistry

    cobalt chloride forms pink crystals. when they are heated water is evolved an they turn blue. can you please explain how you could ue cobalt chloride as a test of water.

    asked by Anonymous on September 5, 2010
  4. chemistry

    Is it true that more potassium bromide can dissolve in distilled water than in a solution of potassium chloride? Im thinking maybe the common ion effect is present here?

    asked by MikeSo on April 3, 2008
  5. Chem

    I got part a but part b I'm having trouble with I keep getting 56.2mL. I'm not sure what the next step is really to find part b. A. How would you prepare 250 mL of a 0.150 M solution of CoCl2 from solid CoCl2 and distilled water?

    asked by Micheal on November 8, 2013
  6. Chemistry

    here is the question. it is a fact that when you add acetone to saturated sodium chloride, the equilibrum shifts towards the right. what observation supports this fact? what is the role of acetone in shifting the equilibrium

    asked by Dalala on March 21, 2010
  7. chemistry

    The label of a bottle containing a solution So of hydrochloric acid carries the following indications :hydrochloric acid of density 1190g/l percentage by mass 37%. We introduce a volume V=4.2ml of So in a volumetric flask of

    asked by vicky on December 27, 2016
  8. chemistry

    The label of a bottle containing a solution So of hydrochloric acid carries the following indications :hydrochloric acid of density 1190g/l percentage by mass 37%. We introduce a volume V=4.2ml of So in a volumetric flask of

    asked by vicky on December 25, 2016
  9. Chem

    Solution rate inquiry lab: For class, we have to design our own lab given the info from class. My question is: Does the INTRO, HYPOTHESIS, PROCEDURE, & DATA CHART all make sense? I feel like I'm missing something or the hypothesis

    asked by Kacey on January 17, 2017
  10. Chem

    At 58.8 degrees C and at a total pressure of 1.00 atm the mole percent of acetone in the vapor state above a solution of acetone and water containing 70. mol % acetone is 87.5%. Assuming the solution to obey Raoult's Law,

    asked by Chris on March 27, 2007

More Similar Questions