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Salts and acids/ bases conceptual question

  1. Jul 30, 2011 #1
    My book says the following:

    NH4NO3 is weakly acidic as a salt because it is composed of the conjugates of the base NH3 and the strong acid HNO3.

    Why does that make it weakly acidic exactly??

    Is it because the HNO3 is a strong acid, therefore it won't steal the protons that are released from the NH4 in solution?
  2. jcsd
  3. Jul 30, 2011 #2
    You pretty much got it.

    Nitric acid HNO3 is a strong acid, so it's conjugate base, NO3- is a very weak base. It will not affect the pH of the solution.

    Ammonia NH3, on the other hand, is a moderately weak base, so it's conjugate acid NH4+ is a moderately strong acid. It will release protons in solution.

    So, as you say, the NH4+ releases protons, the NO3- does not pick up protons, so the net effect is an acidic solution.
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