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Barium chromate

  1. Sep 21, 2009 #1
    Hi guys today in the lab i did reaction of barium chromate with hydrochloric acid and when i add HCL to barium chromate i got a reddish orange solution but when i add sulphuric acid i got a colorless solution with yellow ppt. Why is this so? Shouldn't both give me the same result since they are both acid?
     
  2. jcsd
  3. Sep 21, 2009 #2

    Borek

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    Consult solubility table.

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  4. Sep 21, 2009 #3
    Alright i googled it and found out that sulfur oxide is insoluble in barium so that is the reason why yellow ppt is formed and not a red solution?Well in that case why is it that when i add nitric acid to barium chromate there is no change in color? the solubility table says NO is soluble in anything.
     
  5. Sep 21, 2009 #4

    Borek

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    You don't deal with sulfur oxide nor nictric oxide, you are so wrong I have even no idea where to start the help... Are you sure NO didn't stand for no, as opposed to YES?

    Do you know what a salt is? Have you heard about insoluble salts? Do you know why salts of weak acids dissolve in strong acids? Have you heard about LeChatelier's principle? Dissociation?

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  6. Sep 21, 2009 #5
    actually i was trying to say (SO4)2- haha. Erm the NO is the NO in HNO. Yeap salt is the product formed when acid and base react ya? insoluble salt is a salt that does not dissolve in the solvent? Nope no idea why it dissolve.Yeah LeChatelier's principle. Acid dissocaiation?
     
  7. Sep 21, 2009 #6

    Borek

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    Put all indices and charges on the ions you are writing about, and call them properly. We need a common language. As of now we are wasting time because you speak alkhymystry instead of chemistry. No such thing as NO of HNO.

    What ions are present in the solution?

    Weak acid dissociation combined with LeChatelier's principle - what happens when weak acid is put into low pH solution?

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  8. Sep 21, 2009 #7
    Weak acid in low pH? No dissociation? Aint HNO a strong acid?
     
  9. Sep 21, 2009 #8

    Borek

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    No such thing as HNO and we are talking about the problem you have posted at the very beginning, so don't get distracted.

    I assume you mean that weak acids are not dissociated in low pH. That's correct enough for the problem. What ions are present in the solution?

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  10. Sep 21, 2009 #9
    Ops sorry i was referring to the test with nitric acid.

    Hmm ions... Ba2+, (SO4)2- and CrO4?
     
  11. Sep 21, 2009 #10

    Borek

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    Stop ignoring charges. CrO4 is not an ion.

    We are getting closer. Consult solubility table.

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  12. Sep 21, 2009 #11
    Dude i am not ignoring charges i just dont know what the charge is haha my chem is not that good man. (SO4)2- is not soluble in Ba2+ so that is the reason for the ppt?
     
  13. Sep 21, 2009 #12

    Borek

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    CrO42-, anion of a relatively weak acid H2CrO4. Do you know why chromates are soluble in strong acids? Hint: we have already discussed it partially, what you wrote in #7 is the most important reason behind.

    Geez, alkhymystry again.

    Barium sulfate is not soluble in water - that means, when you have both Ba2+ and SO42- in water, sulfate will preicipitate.

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  14. Sep 21, 2009 #13
    Well i tried but i just cant make them look like chemistry..... alright i see the reason now but one more question. Why nothing happen when i add nitric acid to barium chromate?
     
  15. Sep 21, 2009 #14

    Borek

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    I am not referring to (SO4)2- - while this is not a standard way of writing formulas, it is clear what you mean. You may try SO4-2 or SO4-- in future, these are used quite often. However, when you write about dissolving SO42- in Ba2+ it doesn't make sense.

    Nitric acid should dissolve chromate, perhaps not as good as hydrochloric (it is substantially weaker).

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  16. Sep 21, 2009 #15
    Alright thanks man i will take note of that
     
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