[vverityv]

I'm having trouble writing equations for acids/bases when they dissociate in water.  Basically, I have to identify if a substance is an acid or a base when reacting with H2O and then write a balanced equation.

I'm trying to do what I learned previously and identify what's cation/anions make up the substance, pair them with corresponding cations/anions of water....figure out what's soluble, cancel out spectator ions, write the net ionic equation....but I seem to be getting the wrong equation  

Can anyone help me for the following problems and give me any tips on how to do it?  I would greatly appreciate it! I'm really struggling right now....


Write equations to describe the correct equilibrium when the following chemical
substances are dissolved in aqueous solution (water).  Identify acids/bases and conjugate pairs.
Ignore spectator (unimportant) ions that would not contribute to determining pH.

NH₂OH

CHCl₂COOH

 
(CH)₃NH₃NO₃

KClO

[fledarmus]

What equation are you getting?

[vverityv]

For example with NH₂OH + H₂O  I'm getting NH₂⁺ + OH^-  + H₂⁺ O^-2 --> NH₄O + H₃O

but the answer is NH₂OH + H₂O ---> NH₃⁺OH + OH^- and I'm just not seeing how...?


I guess one of my problems is how to tell if a substance is acting as either an acid or a base since water can be both

[Borek]

Hydroxylamine is similar to ammonia in its reaction with water.

[vverityv]

Right, but there has to be a way to know how to write the equation without just memorizing reactions.  That's what I'm having trouble with.  My professor refuses to tell us how he writes equations, claiming you just "know"

[sjb]

Right, but there has to be a way to know how to write the equation without just memorizing reactions.  That's what I'm having trouble with.  My professor refuses to tell us how he writes equations, claiming you just "know"

I suppose in some regards you have to actually run the experiment and compare to how others have interpreted similar experiments in the past, so this is a sort of memorisation. How do you know that CH₄ is called "methane", rather than say "box" or "stapler"?

[fledarmus]

look at some of the products that you are proposing. For example, you have NH₂⁺ - what would the electronic structure of that compound be? Is that a stable structure? And you are trying to divide water into two protons and a bare O^2- ion. Water separates to H⁺ and OH^-, and then you are trying to make the OH^-, already a strong base, act like an acid by giving up a second proton?

Also look at the electronic structure of the compounds you are starting with. What do you know about lone pairs of electrons in relation to acidity and basicity? What about the strength of N-O single bonds compared to OH or NH single bonds?