Reaction of Metallic Tin with NH4Cl and treatment with Sulfur

Metallic $\ce{Sn}$ is reacted with $\ce{NH\_4Cl}$ and the resulting solution is treated with Sulfur.


1. What is the gaseous product?
2. What is the color of final precipitate?
3. The above resulting solution is added to $\ce{AuCl3}$, resulting in a purple coloured solution. What is the composition of the solution?


I do realise the answer to (3) will be the purple of Cassius i.e colloidal gold in $\ce{Sn(OH)2}$ (as per Vogel's Qualitative Inorganic Analysis textbook fifth edition). But I can't figure out the answer to the first two questions (I tried Googling with no fruitful search).




*Note: this is an incomplete answer because question is unclear till now*



> 
> Metallic $\ce{Sn}$ is reacted with $\ce{NH4Cl}$..
> 
> 
> 


$$\ce{2NH4Cl + Sn → SnCl2 (white ppt.) + 2NH3 (both aq and g.) + H2 ^}$$


Ammonium chloride react with tin to produce tin(II) chloride, ammonia
and hydrogen. ([source](http://chemiday.com/en/reaction/3-1-0-13087))


Some tin(II) chloride will react with aqueous ammonia to form tin (II) hydroxide and amm. chloride.([source](http://chemiday.com/en/reaction/3-1-0-11940))


$$\ce{SnCl2 + 2(NH3•H2O) or NH3(aq) → Sn(OH)2 or SnO.H2O(white ppt.) + 2NH4Cl (white ppt.)}$$



> 
> ..and the resulting solution is treated with Sulfur.
> 
> 
> 


I am suspecting that is **hydrogen sulfide** and not sulfur.(*Are you sure?*)


$$\ce{SnCl2 + H2S → SnS(dark brown ppt.) + HCl}$$


Tin(II) chloride react with hydrogen sulfide to produce tin(II) sulfide and hydrogen chloride. Tin(II) chloride - concentrated solution. Hydrogen sulfide - saturated solution. ([source](http://chemiday.com/en/reaction/3-1-0-11942))


So, answer to your questions:


1. What is the gaseous product?



> 
> Hydrogen, Some ammonia gas.
> 
> 
> 


2. What is the color of **final** precipitate?



> 
> Stannous sulfide ($\ce{SnS}$)- dark brown ppt.
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3. The above resulting solution is added to $\ce{AuCl3}$, resulting in a purple coloured solution. What is the composition of the solution?



> 
> $$\ce{2[AuCl4]- + 4Sn^2+ + 2H2O -> [2Au + Sn(OH)2)](purple ppt.) +
> 3Sn^4+ + 2H+ + 8Cl-}$$
> 
> 
> (Vogel)
> 
> 
> Note: $\ce{AuCl3}$ exist as $\ce{AuCl4-}$ ions in solution.
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> 


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