Question

Identify the correct option:
\[N{a_2}C{O_3} \cdot 10{H_2}O \to N{a_2}C{O_3} \cdot {H_2}O\]
The given reaction is an example of:
A.Efflorescent substance
B.Deliquescent substance
C.Hygroscopic substance
D.None of the above

Answer 1

Hint: Sodium carbonate DE carbohydrate, is also known as natron, with chemical formula of $N{a_2}C{O_3} \cdot 10{H_2}O$ is one of the three hydrates of sodium carbonate are heptahydrate and monohydrate.

Complete step by step answer:
The given reaction is:
\[N{a_2}C{O_3} \cdot 10{H_2}O \to N{a_2}C{O_3} \cdot {H_2}O\]
From the above reaction, we can see that the product is made by removing the water of crystallization which is attached with \[N{a_2}C{O_3}\]from the reactant side. However, the \[N{a_2}C{O_3} \cdot 10{H_2}O\] actually looks dry but it does contain a fixed number of water molecules present in one formula unit of a salt. Now, when this hydrate is heated, it forms anhydrous sodium carbonate which is due to release of the molecules of water of crystallization, this anhydrous compound is also termed as calcined soda.
An efflorescent substance is a chemical substance which loses the water, which is associated with its molecules, through evaporation when exposed to air. As, we can see in the given reaction, that the chemical substance is losing water which was associated with its molecules, so it can be said as the efflorescent substance.
The deliquescent substance is a chemical substance that absorbs moisture from the atmosphere until it gets dissolved in the absorbed water to form a solution. It can be clearly seen in the given reaction, that no such absorption of moisture is taking place, so this is the correct option
Now, the hygroscopic substance is the one which instantly attracts water from its surroundings, either through absorption or adsorption. Also, this is not the case with the given reaction, thus this is also not true.
Hence, the answer is option (A).

Note:
Firstly, anhydrous sodium carbonate is manufactured by the Solvay process (ammonia – soda process) and then it is converted into sodium carbonate decahydrate which is efflorescent in air forming sodium carbonate monohydrate.