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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: remeday86 on February 01, 2009, 01:55:46 AM

Title: ionization in water for HClO4
Post by: remeday86 on February 01, 2009, 01:55:46 AM

Pure HClO4 is molecular. In water it is a strong acid. Write an equation for its ionization in water. Use minimal integer numbers to balance the reaction. Include physical states in your answer, e.g., start with HClO4(l).

-->My answer
HClO4(l) + H2O(l) ::equil:: H3O+(l) + ClO4-(l)

I got this wrong. So, i tried this:

HClO4(l) + H2O(l) ::equil:: H3O+(aq) + ClO4-(aq)

and I still got it wrong.

Title: Re: ionization in water for HClO4
Post by: Arkcon on February 01, 2009, 06:32:35 AM

I like the second one better, the ions should be aqueous, not liquid.  If this is an online test, maybe there are other answering conventions you have to follow.  What else can you try, randomly, along the same lines as your second answer?

Title: Re: ionization in water for HClO4
Post by: remeday86 on February 02, 2009, 04:54:44 PM

Quote from: Arkcon on February 01, 2009, 06:32:35 AM

I like the second one better, the ions should be aqueous, not liquid.  If this is an online test, maybe there are other answering conventions you have to follow.  What else can you try, randomly, along the same lines as your second answer?

I tried:
HClO4(l) + H2O(aq) ::equil::  H3O+(aq) + ClO4-(aq)

but too, didn't work :-\

Title: Re: ionization in water for HClO4
Post by: Astrokel on February 02, 2009, 06:04:40 PM

Hmm, perhaps it has to do with the ability to form hydrogen bonding since it mentioned something about molecular. What about HClO₄.2H₂O?

Title: Re: ionization in water for HClO4
Post by: Fleaker on February 02, 2009, 06:20:04 PM

Remeday,

Perchloric is one of the strongest common acids (stronger than sulfuric, nitric, even HI), why would there be an equilibrium reaction? I suppose in reality it is in equilibrium, but it is so insignificant it shouldn't be written--the equilibrium lies completely to the right.

I think Akron's answer is correct. I don't know about the computer program you're using, but I'll wager that there's some convention that's not being followed. Your second answer seems like a winner to me.

Title: Re: ionization in water for HClO4
Post by: Arkcon on February 02, 2009, 07:00:12 PM

Perhaps the automated quiz wants:

HClO4(aq)   :rarrow:  H+(aq) + ClO4-(aq)

It was the guess I was looking for.  Not really a chemistry answer, just trying to work with the program.  Also, if states of matter are important, H₂O(aq) is a little bit, illogical -- water, in aqueous solution?  And other tricks along those lines.