Question

What happens when:
a. Whater is added to `CaC_(2)` and the resulting gas is passed through dil `H_(2)SO_(4)` containing `HgSO_(4)`. B. Hydrated `MgCl_(2)` is heated in presence of `NH_(4)Cl`. C. `FeCl_(3)` solution is treated with `Mg`. D. `NH_(4)Cl` is heated with `Mg`. e. `CO_(2)` is passed through limewater. f. `SO_(2)` is passed through limewater.

Answer 1

`CaC_(2)+H_(2)OrarrCa(OH)_(2)+underset("Acetylene gas")(C_(2)H_(2)uarr)`

`CaC_(2)` reacts with `H_(2)O` to produce `Ca(OH)_(2)` and acetylene, `C_(2)H_(2)` gas, when `C_(2)H_(2)` gas is further passed through `H_(2)SO_(4)` containing `HgSO_(4)`, acetaldehyde `(CH_(3)CHO)` is produced.
(b). `MgCl_(2).6H_(2)O+NH_(4)ClrarrMgCl_(2).underset("Double salt")(NH_(4)Cl.6H_(2)O`
`MgCl_(2).NH_(4)Cl.6H_(2)Ooverset(Delta)(rarr)MgCl_(2).NH_(4)Cl+6H_(2)O`
`MgCl_(2).NH_(4)Cloverset(Delta)(rarr)MgCl_(2)+NH_(4)Cl`
Hence, anhydrous `MgCl_(2)` is produced.
(c). `FeCl_(3)+3H_(2)OrarrFe(OH)_(3)+3HCl`
`Mg+2HClrarrMgCl_(2)+H_(2)`
(d). `Mg+2NH_(4)ClrarrMgCl_(2)+2NH_(3)+H_(2)`
(e). When `CO_(2)` is passed through limewater initially the solution becomes milky due to formation of `CaCO_(3)`. When excess of `CO_(2)` is passed, the solution becomes clear again due to the formation of `Ca(HCO_(3))_(2)`
`underset("Limewater")(Ca(OH)_(2))+CO_(2)rarrunderset(("Milkiness"))(CaCO_(3))+H_(2)O`
`CaCO_(3)+underset(("excess"))(CO_(2))+H_(2)Orarrunderset(("Soluble, hence the milkiness disappears and the solution becomes clear"))(Ca(HCO_(3))_(2))`
(f). `Ca(OH)_(2)+SO_(2)rarrCaSO_(3)+H_(2)O`
Solution becomes milky due to formation of `CaSO_(3)`