A white amorphous powder A on heating yields a colorless, noncombustible gas B and a solid C. The latter compound assumes a yellow color on heating and changes to white on cooling. C dissolves in dilute hydrochloric acid and the resulting solution gives a white precipitate with K4Fe(CN)6 solution. Dissolves in dilute HCl with the evolution of gas, which is identical in all respect with B. The gas B turns lime water milky, but the milkiness disappears with the continuous passage of gas. The solution of A as obtained above gives a white precipitate D on the addition of an excess of NH4OH and passing H2S. Another portion of the solution gives initially a white precipitate E on the addition of NaOH solution, which dissolves on further addition of the base.
Identify the compound B.
A white amorphous powder A on heating yields a colorless, noncombustible gas B and a solid C. The latter compound assumes a yellow color on heating and changes to white on cooling. C dissolves in dilute hydrochloric acid and the resulting solution gives a white precipitate with K4Fe(CN)6 solution. Dissolves in dilute HCl with the evolution of gas, which is identical in all respect with B. The gas B turns lime water milky, but the milkiness disappears with the continuous passage of gas. The solution of A as obtained above gives a white precipitate D on the addition of an excess of NH4OH and passing H2S. Another portion of the solution gives initially a white precipitate E on the addition of NaOH solution, which dissolves on further addition of the base.
The correct option is D CO2
The solid that is yellow when hot and white when cold is zinc oxide. The gas is carbon dioxide,from its behaviour towards lime water. In alkaline medium, zinc sulphide is precipitated by hydrogen sulphide gas. The precipitate of zinc hydroxide is soluble in excess of sodium hydroxide due to the formation of sodium zincate.
AΔ−→ZnO+B
ZnCO3Δ−→ZnO+CO2
ZnO+2HCl⟶ZnCl2+H2O
2ZnCl2+K4[Fe(CN)6]⟶4KCl+Zn2[Fe(CN)6]↓
CO2+Ca(OH)2⟶H2O+CaCO3↓Milkiness
CaCO3+CO2+H2O⟶Ca(HCO3)2Soluble
ZnCO3+HCl⟶CO2↑+ZnCl2
ZnCl2+H2SNH4OH−−−−−→2HCl+ZnS↓
ZnCl2+NaOH⟶Zn(OH)2↓+2NaCl
Zn(OH)2NaOH−−−−→NaZnO2(soluble)
The solid that is yellow when hot and white when cold is zinc oxide. The gas is carbon dioxide,from its behaviour towards lime water. In alkaline medium, zinc sulphide is precipitated by hydrogen sulphide gas. The precipitate of zinc hydroxide is soluble in excess of sodium hydroxide due to the formation of sodium zincate.
AΔ−→ZnO+B
ZnCO3Δ−→ZnO+CO2
ZnO+2HCl⟶ZnCl2+H2O
2ZnCl2+K4[Fe(CN)6]⟶4KCl+Zn2[Fe(CN)6]↓
CO2+Ca(OH)2⟶H2O+CaCO3↓Milkiness
CaCO3+CO2+H2O⟶Ca(HCO3)2Soluble
ZnCO3+HCl⟶CO2↑+ZnCl2
ZnCl2+H2SNH4OH−−−−−→2HCl+ZnS↓
ZnCl2+NaOH⟶Zn(OH)2↓+2NaCl
Zn(OH)2NaOH−−−−→NaZnO2(soluble)
