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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: jennielynn_1980 on July 07, 2006, 02:52:51 PM

Title: Cannot balance this to save my life
Post by: jennielynn_1980 on July 07, 2006, 02:52:51 PM

NH₄ + HIO₃ --> NH₄I + H₂O

ammonium + iodic acid --> ammonium iodide + water

I can balance equations no problem but this one is giving me grief.  Is there something about it that is making it difficult?  Can someone point me in the right direction?  I keep getting 10 hydrogen on the left  compared with 5 on the right but all else balances out.

Thanks :)

Title: Re: Cannot balance this to save my life
Post by: Alberto_Kravina on July 07, 2006, 02:55:58 PM

Quote

NH4 + HIO3 --> NH4I + H2O

ammonium + iodic acid --> ammonium iodide + water

That doesn't make sense: NH₄ doesn't exist, it's an ion (NH₄⁺), I think you mean ammonia (NH₃)

Title: Re: Cannot balance this to save my life
Post by: Dude on July 07, 2006, 03:04:52 PM

Yes.  What Alberto said about ammonia.  Furthermore, there is no reason to suspect anything other than an acid base reaction between iodic acid and ammonia as NH3.  You are missing an anion if there is a reduction occurring.

Title: Re: Cannot balance this to save my life
Post by: sdekivit on July 07, 2006, 03:07:30 PM

this reaction is in all ways: weird.

Title: Re: Cannot balance this to save my life
Post by: Donaldson Tan on July 07, 2006, 03:29:09 PM

I doubt the product is an iodide. It should be an iodate.

Title: Re: Cannot balance this to save my life
Post by: constant thinker on July 07, 2006, 09:30:52 PM

NH₄⁺ exists. It's ammonium (not ammonia), so jennielynn_1980 got its name right.

I don't really get this reaction though. A cation + an acid?? There must be something else that's part of the ammonium or...

NH₃ + HIO₃ makes more sense to me.

How about:

NH₃ + HIO₃ --> NH₄IO₃

The product is ammonium iodate. In this case both Alberto_Kravina and geodome are right.

Were you given this equation as you showed us, jennielynn_1980?

By the way, balancing the equation I gave you is wicked easy.

Title: Re: Cannot balance this to save my life
Post by: Donaldson Tan on July 08, 2006, 08:59:16 AM

When iodate oxidise a substance, the iodate is reduced to iodide. Unfortunately, iodate is not an oxidising agent powerful enough to oxidise ammonia. You may refer to the table of standard reduction potential for more information.

Title: Re: Cannot balance this to save my life
Post by: billnotgatez on July 08, 2006, 10:17:10 AM

Question
Should the original unbalanced formula left side be?

NH₄⁺¹ + OH^-1 + HIO₃

instead of  HIO₃  can you use  HOIO₂

Title: Re: Cannot balance this to save my life
Post by: jennielynn_1980 on July 08, 2006, 01:46:24 PM

I guess I have gotten some of the equation wrong.  The original question was to right equation for the neutralization reacting that resulted in the salt ammonium iodide.
I thought a neutralization would have to result from an acid and a base producing the salt ammonium iodide and water.  SO the right side of the equation should be correct if my assumption is correct meaning NH₄I + H₂O is right but the left side is screwy.

I think the base should be NH₄OH instead of the NH₄.  But what acid is it?  No matter what acid I think of, the equation doesn't balance.

Title: Re: Cannot balance this to save my life
Post by: Borek on July 08, 2006, 01:54:15 PM

Iodide or iodate? HI or HIO₃?

Title: Re: Cannot balance this to save my life
Post by: jennielynn_1980 on July 08, 2006, 02:11:43 PM

Iodide


Does this work then?

NH₄OH + HI --> NH₄I + H₂O

ammonium hydroxide + hydroiodic acid -->ammonium iodide + water

Title: Re: Cannot balance this to save my life
Post by: Donaldson Tan on July 08, 2006, 02:26:11 PM

I would rewrite NH₄OH as NH₃ + H₂O because you are actually referring to aqueous ammonia.

NH₃ + H₂O <-> NH₄⁺ + OH^-

Since ammonia is a weak base, the position of the equilibrium above would be left and therefore there is significant proportion of ammonia in the aqueous medium than there is  NH₄⁺. Hence, I will rewrite your neutralisation equation as:
NH₃ + H₂O + HI ->  NH₄I + H₂O

which simplifies to:
NH₃ + HI ->  NH₄I

Title: Re: Cannot balance this to save my life
Post by: jennielynn_1980 on July 08, 2006, 02:57:14 PM

Quote from: geodome on July 08, 2006, 02:26:11 PM

I would rewrite NH₄OH as NH₃ + H₂O because you are actually referring to aqueous ammonia.

NH₃ + H₂O <-> NH₄⁺ + OH^-

Since ammonia is a weak base, the position of the equilibrium above would be left and therefore there is significant proportion of ammonia in the aqueous medium than there is  NH₄⁺. Hence, I will rewrite your neutralisation equation as:
NH₃ + H₂O + HI ->  NH₄I + H₂O

which simplifies to:
NH₃ + HI ->  NH₄I

Thanks :)  I haven't studied equilibrium yet so I wouldn't have known that.

Thanks to everyone for your help and patience!