Aqua Regia, HCL, NH4NO3?

[budullewraagh]

yes. hydroiodic is more soluble in water than hydrobromic, hydrobromic is more soluble than hydrochloric and hydrochloric is more soluble than hydrofluoric. this is because the bond between hydrogen and higher halides is stronger than that of hydrogen and lower halides

[YT2095]

and try not to get HI on your hands, I have a bottle of it here and got some on me, it took about a week for the stain to go!

[pulkit]

and try not to get HI on your hands, I have a bottle of it here and got some on me, it took about a week for the stain to go!

 

 

Like the yellowing that nitric acid causes, did this too impart some colour to your skin ? )

 

And out of curiosity, is HI colourles in aqueous solution ?

[budullewraagh]

yes, HI is colorless in aqueous solution. colored solutions tend to have transition metals.

[max.yevs]

im not sure, but i think HCl is a stronger acid HNO3 (given that HNO3 is more corrosive as an oxidizer than an acid), meaning that you can just mix HCl with NH4NO3 to get NH4Cl and HNO3...

 

if not, H2SO4 will definately do the job: NH4NO3 + H2SO4 > (NH4)2 SO4 + 2HNO3...

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yes im pretty sure HCl will react with NH4NO3 to form nitric acid (and ammonium chloride)

 

I ran the equation through a thermochemical calculator-

 

NH4NO3(s) + HCl(g) = NH4Cl(s) + HNO3(l) + 30.84kJ

 

showing that this reaction should occur spontaneously

 

but ill be able to tell for sure if it works very soon...

[jdurg]

No need to dig up dead posts, plus, when you do a thermodynamic calculation the fact that the enthalpy is positive means that it is most likely NOT going to occur. For reactions to be spontaneous, the Gibbs Free Energy MUST be negative. Only in cases where there's a significant entropic difference will a reaction that is positive in enthalpy be spontaneous. So no. Your proposed reaction will not work. If it did, people would use HCl and NH4NO3 for making aqua regia since NH4NO3 is much easier to store than HNO3.

[max.yevs]

ok yeah you're right it would not have to be spontaneous, but in this case, i think it would be since ammonium nitrate and hcl ionize in solution anyways...

 

and yeah sorry when i was posting this i didnt realize id be writing way back on the second page

[UC]

No need to dig up dead posts, plus, when you do a thermodynamic calculation the fact that the enthalpy is positive means that it is most likely NOT going to occur. For reactions to be spontaneous, the Gibbs Free Energy MUST be negative. Only in cases where there's a significant entropic difference will a reaction that is positive in enthalpy be spontaneous. So no. Your proposed reaction will not work. If it did, people would use HCl and NH4NO3 for making aqua regia since NH4NO3 is much easier to store than HNO3.

 

This is actually well known, although NaNO3 is usually used for other reasons. In solution, you have ions. The salts are not very important. As long as there are NO3-, H3O+, and Cl- ions around, the mixture will work. It is known as "poor man's aqua regia." Using NH4NO3 is a bad move since chlorine might be formed in the mix and this would make chloramines or NCl3 and also because the ammonium cation precipitates things like Hexachloroplatinate ion, preventing dissolution.

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yes, HI is colorless in aqueous solution. colored solutions tend to have transition metals.

 

This isn't the issue so much as iodine stains. HI is very easily oxidized by air to I2 and solutions often have a brown tinge from this.

Edited March 18, 2009 by UC
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