Why is tin and HCl rxn so slow?

Quote: Originally posted by DraconicAcid

I wonder if copper would catalyze the reaction, as it does for zinc and aluminum.

Well I used tin solder which is 99% tin and 1% copper and it still took days; if the copper did indeed catalyze the reaction, I'd hate to see how slow it is without copper!

[Edited on 28-6-2020 by SplendidAcylation]

Quote: Originally posted by SplendidAcylation

I did this reaction recently It is indeed very slow, I reasoned that it is because of tin's position in the reactivity series of metals; of the metals more electropositive than hydrogen, tin is the second most electronegative, after lead. So when it comes to dissolving metals in HCl, lead will be the slowest, followed by tin.

Quote: Originally posted by DraconicAcid

Aluminum won't react with copper(II) ions in the absence of chloride ions; iron will, even though aluminum is much more reactive.

I would try hammering the tin into flat flakes ot a ribbon.

I once dropped a small ingot of tin into a flask of 36% HCl ... it only took a few weeks to dissolve
A black powder (tin oxide ?) kept loosely coating the surface,
a quick swirl and the powder dissolved very quickly,
so as well as maximising surface area,
some kind of constant agitation should significantly speed up the process - I guess.

Quote: Originally posted by DraconicAcid

Quote: Originally posted by SplendidAcylation   I did this reaction recently It is indeed very slow, I reasoned that it is because of tin's position in the reactivity series of metals; of the metals more electropositive than hydrogen, tin is the second most electronegative, after lead. So when it comes to dissolving metals in HCl, lead will be the slowest, followed by tin. The reactivity series is a thermodynamic listing- kinetics are independent of thermodynamics. There are many single replacement-type reactions which are spontaneous, but just don't go at any appreciable rate. Aluminum won't react with copper(II) ions in the absence of chloride ions; iron will, even though aluminum is much more reactive.

Quote: Originally posted by j_sum1

I forget which youtuber it was... But I have followed his example: Melt tin in a large container. Swirl it around while molten so that it solidifies into a thin foil-like shape. Then cut into pieces and dissolve in conc HCl while stirring. This reduces the time from days to a few hours. I believe it can go faster with heating, but I avoid warming concentrated hydrochloric acid. I think some H2O2 may help too. Worth an experiment. The issue I believe is the oxide coating. But there may be other factors. Maybe related to crystalline structure, grain size or grain boundaty effects.

Quote: Originally posted by SplendidAcylation

I did this reaction recently It is indeed very slow, I reasoned that it is because of tin's position in the reactivity series of metals; of the metals more electropositive than hydrogen, tin is the second most electronegative, after lead. So when it comes to dissolving metals in HCl, lead will be the slowest, followed by tin. I agree with j_sum1, increasing the surface area and/or heating the acid will both help. To increase the surface area, I found the following method more effective; Melt the tin, and drop it from a height onto an appropriate surface. I dropped a spoonful of molten tin about 2 metres onto tiles, and I got a big splatter of tin, very thin, and without the thick bits that tend to form when doing the swirling method Then cut it into small pieces. Even when I did this, it still took days, until I eventually lost patience and boiled it in acid... This made a huge difference, and what remained dissolved within minutes Be careful with boiling HCl, if you get it on your skin you'll be okay provided you rinse it off with cold water, but don't get it in your eyes Also proper ventilation is necessary, as the vapours from hot (and cold, to a lesser extent) HCl will rapidly corrode practically any metal Quote: Originally posted by DraconicAcid   I wonder if copper would catalyze the reaction, as it does for zinc and aluminum. Well I used tin solder which is 99% tin and 1% copper and it still took days; if the copper did indeed catalyze the reaction, I'd hate to see how slow it is without copper! [Edited on 28-6-2020 by SplendidAcylation]

Quote: Originally posted by Sulaiman

I would try hammering the tin into flat flakes ot a ribbon. I once dropped a small ingot of tin into a flask of 36% HCl ... it only took a few weeks to dissolve A black powder (tin oxide ?) kept loosely coating the surface, a quick swirl and the powder dissolved very quickly, so as well as maximising surface area, some kind of constant agitation should significantly speed up the process - I guess.

Weeks!
Okay thanks Ill try to get some way to agitate the mixture.

Quote: Originally posted by Metacelsus

From personal experience, Sn/HCl reductions of nitro groups go very quickly, producing tin chloride and an amine hydrochloride. When I did this, I melted the tin and poured it into water to make tin granules, which I then used. Maybe adding an oxidizer would help speed things up. Or perhaps you could use the tin as an anode in an electrolytic cell.

I'll test this out if all else fails. Thanks tho!

Quote: Originally posted by DraconicAcid

Quote: Originally posted by SplendidAcylation   I did this reaction recently It is indeed very slow, I reasoned that it is because of tin's position in the reactivity series of metals; of the metals more electropositive than hydrogen, tin is the second most electronegative, after lead. So when it comes to dissolving metals in HCl, lead will be the slowest, followed by tin. The reactivity series is a thermodynamic listing- kinetics are independent of thermodynamics. There are many single replacement-type reactions which are spontaneous, but just don't go at any appreciable rate. Aluminum won't react with copper(II) ions in the absence of chloride ions; iron will, even though aluminum is much more reactive.

That's interesting, I stand corrected

I have tried the aluminium + copper (II) reaction, and I was indeed surprised to find it didn't work, I just assumed it was due to the passivation layer

OK, I've tried that, eventually.

I must admit that the usage of aqua regia vs 36% HCl has no speed benefit.

I did the experiment by dissolving pieces of tin metal I created by dropping the melted metal through a small glass funnel into glicerol and water (they are quite similar, have a shiny surface; the usage of glycerol is more convenient because it doesn't create kind of steam explosions but do it under ventilation).

I used both big and small pieces.

The aqua regia was prepared by mixing 6 ml of 36% HCl and 2 ml of azeotropic HNO3 (the fraction distilled on 121C).

Both tubes show good reaction but aqua regia seams produce 2-3 times more bubbles, so the speed is higher. But I noticed it is just because this reaction is exotermic (it oxidise tin to valence IV) and when I heated the second (pure HCl) tube to the same temperature on a water bath the speed of bubbles was almos the same:



Also I tried to dissolve KNO3 in 36 HCl, but it didn't. So, I've prepared solution of KNO3 in boiling water and have poured it into 36% HCl. It immediately produced precipitation of KCl and created some mixture with the same color as the genuine aqua regia, but this need to be decanted from KCl crystalls because they prevent to use it for dissolving of metals.

Generally, with or without usage of water bath, 36% HCl attacks tin pretty well, I can compare with its action on chrome metal, well a bit slower but still doable.

If you have different experience that is probably due to usage of some alloy, not a pure ("crying") tin.



[Edited on 31-10-2020 by teodor]

Quote: Originally posted by SplendidAcylation

I have tried the aluminium + copper (II) reaction, and I was indeed surprised to find it didn't work, I just assumed it was due to the passivation layer