Bleaching powder is obtained by passing `Cl_(2)` into `Ca(OH)_(2)` . Though bleaching powder is often written as `Ca(O Cl)_(2)` , it is actually a mixture .
`3Ca (OH)_(2) + 2Cl_(2) to Caunderset("Bleaching powder")((O Cl)_(2) . Ca(OH)_(2)) . CaCl_(2). 2H_(2)O`