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titrating NH3 with HI. pH at end point is 5 and not 7. why? watch

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    A fellow student said acid is slightly in excess. Someone else said because HI is a strong acid.
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    (Original post by thebrahmabull)
    A fellow student said acid is slightly in excess. Someone else said because HI is a strong acid.
    It's a strong acid plus a weak base.

    At the equivalence point (when you have only salt present) the pH is acidic as the salt itself is acidic by hydrolysis.
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    For titrations: if the base is stronger than the acid, the equivalence point will be above 7, and if the acid is stronger than the base, the equivalence point will be below 7.
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    (Original post by charco)
    It's a strong acid plus a weak base.

    At the equivalence point (when you have only salt present) the pH is acidic as the salt itself is acidic by hydrolysis.
    Thanks!
    Just curious, would the dissociations be like this?

    HI + NH3 = NH4+ + I-
    NH4+ + H20 = H30+ + NH3

    (The equal signs are reversible signs)
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    (Original post by Es0phagus)
    For titrations: if the base is stronger than the acid, the equivalence point will be above 7, and if the acid is stronger than the base, the equivalence point will be below 7.
    Thank you.
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    (Original post by thebrahmabull)
    Thanks!
    Just curious, would the dissociations be like this?

    HI + NH3 = NH4+ + I-
    NH4+ + H20 = H30+ + NH3

    (The equal signs are reversible signs)
    yes
 
 
 
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