Question #32ecf

1 Answer
May 11, 2015

Whitewash is made by mixing quicklime, which is another name for calcium oxide, #CaO#, with water.

Calcium oxide is obtained from the thermal decomposition reaction of limestone, which is another name used for calcium carbonate, #CaCO_3#. When you heat limestone, you convert it to calcium oxide and carbon dioxide.

#CaCO_(3(s)) -> CaO_((s)) + CO_(2(g))#

When calcium oxide is mixed, or slacked, with water, you get slacked lime, which is calcium hydroxide.

#CaO_((s)) + H_2O_((l)) -> Ca(OH)_(2(s))#

Calcium hydroxide is one of the main ingreadients in whitewash, along with chalk, or calcium carbonate, #CaCO_3#.

Calcium hydroxide is converted into calcium carbonate by a process called carbonation

#Ca(OH)_(2(s)) + CO_text(2(g]) -> CaCO_text(3(s]) + H_2O_((l))#

So, as a conclusion, whitewash is a solution that cxontains calcium hydroxide (slacked lime) and calcium carbonate (chalk).