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    The student adds methanoic acid, HCOOH (ka=n 1.82 x 10-4 mol dm-3) to butanoic acid. A reaction takes place to form an equilibrium mixture containing two acid base pairs. Complete the equilibrium below and label the conjugate acid base pairs.

    HCOOH + CH3(CH2)2COOH (equilibrium sign) ................ + ................

    Is this right?

    HCOOH + CH3(CH2)2COOH (equilibrium sign) HCOOH2 + CH3(CH2)2COO-
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    What are the Ka values for the acids?
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    (Original post by AtomicMan)
    What are the Ka values for the acids?
    It's 1.82 x 10-4, sorry I forgot to add it in the OP. I'll add it now.
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    (Original post by tazmaniac97)
    It's 1.82 x 10-4, sorry I forgot to add it in the OP. I'll add it now.
    Whats the Ka for butanoic acid? This all depends on their relative Ka values. What do you know about the acid-dissociation constant?
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    (Original post by AtomicMan)
    Whats the Ka for butanoic acid? This all depends on their relative Ka values. What do you know about the acid-dissociation constant?
    1.51 x 10-5 mol dm-3
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    (Original post by AtomicMan)
    Whats the Ka for butanoic acid? This all depends on their relative Ka values. What do you know about the acid-dissociation constant?
    Oh I think I get it now, the strongest acid would be the one that dissociates, so the correct answer is:

    HCOOH + CH3(CH2)2COOH (equilibrium sign) HCOO- + CH3(CH2)2COOH2

    Am I right?
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    (Original post by tazmaniac97)
    1.51 x 10-5 mol dm-3
    Right ok, acids with higher Ka's will basically dissociate more often to release H+ ions. So butanoic acid would dissociate more than methanoic acid, so butanoic acids acts as the acid and protonates methanoic acid.

    Your answer is correct

    (Original post by tazmaniac97)
    Oh I think I get it now, the strongest acid would be the one that dissociates, so the correct answer is:

    HCOOH + CH3(CH2)2COOH (equilibrium sign) HCOO- + CH3(CH2)2COOH2

    Am I right?
    No, you were right at first A stronger acid will have a higher Ka value.
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    (Original post by AtomicMan)
    Right ok, acids with higher Ka's will basically dissociate more often to release H+ ions. So butanoic acid would dissociate more than methanoic acid, so butanoic acids acts as the acid and protonates methanoic acid.

    Your answer is correct



    No, you were right at first A stronger acid will have a higher Ka value.
    methanoic acid is the stronger and so disociates providing a proton for the butanoic acid.
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    (Original post by tazmaniac97)
    Oh I think I get it now, the strongest acid would be the one that dissociates, so the correct answer is:

    HCOOH + CH3(CH2)2COOH (equilibrium sign) HCOO- + CH3(CH2)2COOH2

    Am I right?
    This is correct ...
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    (Original post by charco)
    methanoic acid is the stronger and so disociates providing a proton for the butanoic acid.
    Woops, read the -5 as a -3 :lol: Yes, methanoic acid is stronger.
 
 
 
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