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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Kuahji on May 02, 2008, 12:58:52 AM

Title: Reactions that don't occur at room temp
Post by: Kuahji on May 02, 2008, 12:58:52 AM
Which reaction does not readily occur at room temperature?

2 HCl + Zn(OH)2 -> ZnCl2 + 2 H2O

Cu2+ (aq) + 4 NH3 -> Cu(NH3)4 2+ (aq)

NH3 + HCl -> NH4Cl

2 HCl -> H2 + Cl2

Given only the given information, how can I tell which one doesn't occur at room temperature?  The only thing I could really think of, is perhaps entropy.  NH3 + HCl -> NH4Cl does appear to go from 2 molecules to one but so does Cu2+ (aq) + 4 NH3 -> Cu(NH3)4 2+ (aq), here though it is just (aq).  Am I at least headed in the right direction?  Do I even need to know the different states or more information?
Title: Re: Reactions that don't occur at room temp
Post by: DrCMS on May 02, 2008, 05:27:07 AM
What do 3 of the reactions have in common?
Under what conditions do that type of reaction occur?
Title: Re: Reactions that don't occur at room temp
Post by: AWK on May 02, 2008, 06:43:28 AM
Which reaction can be called a thermal decomposition?
Title: Re: Reactions that don't occur at room temp
Post by: Kuahji on May 02, 2008, 06:14:06 PM
Quote from: AWK on May 02, 2008, 06:43:28 AM
Which reaction can be called a thermal decomposition?

Didn't think about it like that, we've been talking so much about entropy of late, totally forgot about thermal decomposition.   :)

But that does make sense & would really only leave one reaction left, 2 HCl -> H2 + Cl2, so that is what I'm going with. 

Thank you both for responding.