On the occasion of Diwali, Rohan used solution of calcium hydroxide (slaked) for white washing walls. After two or three days of white washing a compound is formed. This formed compound gives a shiny appearance to the walls. Read the above passage and answer the following questions.
(i) What is the chemical name of compound formed after 2-3 days of white washing?
(ii) Write the chemical reaction occurring during calcium hydroxide to a shiny appearance to the walls.
(iii) Name the type of reaction.
Slaked lime is the common name used for calcium hydroxide Ca(OH)2 . It is formed by the reaction of quick lime CaO with water.
(i) The chemical name of compound formed is calcium carbonate.
Explanation: The calcium hydroxide used for white washing the walls reacts with the carbon dioxide (CO2) present in the air to form Calcium carbonate (CaCO3) which gives shiny appearance to the walls.
(ii) The chemical reaction occurring during the conversion of slaked lime (calcium hydroxide) to calcium carbonate which gives the shiny appearance to the walls is as follows:
(iii) The Type of reaction is exothermic.
Explanation: A reaction which involves the release of heat when the product formation takes place is known as an exothermic reaction. The reaction of calcium hydroxide (base) with CO2 (acidic non-metal oxide) is a neutralization reaction in which heat is evolved. Thus it is an exothermic reaction.