Question

Explain the Action of heat on aluminum hydroxide.

Answer 1

Hint: We know that metal hydroxides are strong bases, and metal hydroxide contains hydroxide ions and ions of the specific metal. Metal hydroxides on heating yield metals oxides and the side product obtained will be water.

Complete step by step answer:
Let us know about decomposition reactions.
We can say decomposition reactions are the opposite of a combination reaction because decomposition reaction involves the breaking of a substance into simpler substances. Such a reaction is easy to recognize because there is one reactant and more than one product.
We can write the general chemical reaction for a decomposition reaction as,
$AB\xrightarrow{{}}A + B$
Let us discuss the decomposition reaction of sodium chlorate to sodium chloride and oxygen. The balanced reaction is,
$2NaCl{O_3}\left( s \right)\xrightarrow{{}}2NaCl\left( s \right) + 3{O_2}\left( g \right)$
We must know that the heating of metal hydroxide is also a decomposition reaction. Metal hydroxide when heated decomposes to form metal oxide along with side product water.
When we heat aluminum hydroxide, aluminum hydroxide decomposes to form aluminum oxide and water. We can give the decomposition reaction of aluminum hydroxide as,
$2Al{\left( {OH} \right)_3}\xrightarrow{{Heat}}A{l_2}O{ _3} + 3{H_2}O$
We know that the action of heat on metal hydroxides can also be called thermal decomposition of metal hydroxides.
We have to know that when some unstable acids are decomposed, the products formed will be nonmetal oxides and water.
Let us take the decomposition of carbonic acid.We know that carbonic acid is unstable. It easily undergoes decomposition at room temperature to form carbon dioxide and water.
${H_2}C{O_3}\left( {aq} \right)\xrightarrow{{}}C{O_2}\left( g \right) + {H_2}O\left( l \right)$


Note:
We know that the chemical decomposition that is caused by heat is known as thermal decomposition (or) thermolysis. The temperature at which the substance decomposes chemically is called decomposition temperature. We know that the decomposition reactions are endothermic reactions because they absorb heat energy to break the chemical bonds while undergoing decomposition. Metal carbonates also undergo decomposition reaction to form metal oxides and carbon dioxide gas. Let us give an example of the decomposition reaction of calcium carbonate. When calcium carbonate undergoes decomposition, the products are formed with calcium oxide with evolution of carbon dioxide.
We can write the chemical reaction as,
$CaC{O_3}\left( s \right)\xrightarrow{\Delta }CaO\left( s \right) + C{O_2}\left( g \right)$
Let us discuss another example of thermal decomposition is decomposition of copper carbonate.
Copper carbonate undergoes thermal decomposition to give copper oxide and carbon dioxide as their products. We can write the thermal decomposition of copper carbonate as,
$CuC{O_3}\left( s \right)\xrightarrow{\Delta }CuO\left( s \right) + C{O_2}\left( g \right)$.