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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: ticmmae on September 20, 2011, 03:12:43 AM

Title: Net ionic equation Help
Post by: ticmmae on September 20, 2011, 03:12:43 AM

Hi!
Please help me!

It is asking for net ionic equation of dilute nitric acid + solid mercury (I) carbonate reaction.

I have guessed that full equation is Hg2CO3 + 4HNO3 = CO2+h2+H2o+2Hg(NO3)2 and ionic equation is Hg2CO3(s) + 4H+ -> CO2 + H2 + H2O + 2Hg+.

Is this right?

Also, can someone help me find net ionic equation for oxidation of acidic aq solution of propanal to propanoic acid with a solution of potassium dichromate?

Thanks!

Title: Re: Net ionic equation Help
Post by: Dan on September 20, 2011, 03:48:20 AM

Your chemical equation is incorrect, mercury(I) nitrate is formed under these conditions. To make make mercury(II) nitrate you'd need hot, concentrated HNO₃.

Given this info, you should be able to do the question - it is simpler that what you have attempted.

Title: Re: Net ionic equation Help
Post by: AWK on September 20, 2011, 05:11:20 AM

There are different errors in both posts.
In the first one - H₂ cannot exist in the presence of strong oxidizer - then you should expect not H₂ but product of reduction of HNO₃ - NO or NO₂ depending on concentration of HNO₃.
Moreover, this concerns both posts, Hg₂(NO₃)₂ itself spontaneously decomposes to Hg and Hg(NO₃)_2, and Hg can react with diluted HNO₃ to form Hg₂(NO₃)₂. Since the decomposition is not extremely fast, in the case of diluted acid you can expect both nitrates (of course then the reaction is difficult to balancing).
Concentrated acid is needed for conversion of Hg₂Cl₂ or other Hg(I) fluorides to soluble  Hg(II) nitrates.

All mercury salts with acids that contain oxygen are predominantly ionic than you can balance redox by a half reaction method using Hg₂²⁺ and NO₃^-