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How can you tell what will happen in a reaction?

  1. Jul 4, 2014 #1

    RJLiberator

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    Okay, I need some guidance.

    I've tried googling some answers to this question and nothing has really helped me. It's kind of a common sense question, perhaps?

    However, my common sense of chemistry reactions is quite low. I am wondering if there is a trick to questions like these:

    "Identify the solid formed from the reaction between Mg(NO3)2 and Na2SO4 in aqueous solution. Write ""no reaction"" if no precipitate is formed."

    "Identify the solid formed from the reaction between BaS and PbNO3 in aqueous solution. Write ""no reaction"" if no precipitate is formed."

    "Identify the solid formed from the reaction between MgCl2 and NH4OH in aqueous solution. Write ""no reaction"" if no precipitate is formed."

    How do I go about answering these? My first step would be to write down the products and reactants in an equation, correct? But how do I KNOW if one is aq, l, g, s ?

    Thanks for any tips.
     
  2. jcsd
  3. Jul 4, 2014 #2

    HallsofIvy

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    Well, you know whether given compounds are liquid, solid, or gas at room temperature don't you?

    (I take it "aq" means "aqueous". I am surprised to see it in that list. "aqueous" here simply means that the reaction occurs in water. It is NOT a state of a product.)
     
  4. Jul 4, 2014 #3

    AlephZero

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    You find a chart like http://en.wikipedia.org/wiki/Solubility_chart and learn it.

    Look for the common factors - like "all nitrates are soluble", and so are nearly all halides, except for silver and lead.
     
  5. Jul 4, 2014 #4

    RJLiberator

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    Hey guys,

    Thanks for the tips in the right direction. I am going to begin my studies on this solubility chart. This is what we went over in our previous class. I will learn this and should have a better understanding of things. I will post back if I am lost on something.

    Thank you, kindly.
     
  6. Jul 5, 2014 #5

    RJLiberator

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    In using this chart, I have failed.

    "Identify the solid formed from the reaction between NaCl and AgNO3 in aqueous solution. Write ""no reaction"" if no precipitate is formed."

    My answer: NaNO3

    I figure, the equation is as follows:

    NaCl + AgNO3 ---> NaNO3 + AgCl

    According to the chart NaNO3 is soluble. So that means it will dissolve in water.
    Whereas AgCl is insoluble meaning it will be the solid.

    Is this the correct answer now? --> AgCl
     
  7. Jul 5, 2014 #6
    Yes.
     
  8. Jul 5, 2014 #7

    RJLiberator

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    Excellent. It looks like I am on the right track then. Thanks for the confirmation.
     
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