Which is obtained, when H2 S is passed through the solution of sodium zincate?
When H2S gas is passed into an aqueous solution of ZnCl2, Zn2+ ions are completely precipitated forming white precipitate of zinc sulphide. ZnCl2+HCl→ZnS↓(white ppt)+2HCl Zinc sulphide is insoluble in solutions of caustic soda giving white precipitate of zinc hydroxide but on heating with excess of caustic soda sodium zincate is formed. ZnCl2+2NaOH→Zn(OH)2)↓(white ppt)+2NaCl Zn(OH)2+2NaOH→Na2ZnO2+2H2O Zinc sulphide dissolves in dilute hydrochloric acid forming zinc chloride. ZnS+2HCl→ZnCl2+H2S
