Question

Carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water.
${\text{Ca(OH}}{{\text{)}}_{\text{2}}}{\text{ + C}}{{\text{O}}_{\text{2}}} \to {\text{CaC}}{{\text{O}}_{\text{3}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$
From the above reaction, what can we conclude about ${\text{C}}{{\text{O}}_{\text{2}}}$ ?
(A) Acidic
(B) Basic
(C) Amphoteric
(D) Neutral

Answer 1

In the above question, it is asked about the nature of ${\text{C}}{{\text{O}}_{\text{2}}}$ when it reacts with calcium hydroxide to form calcium carbonate. Since, we know that calcium carbonate is a salt and a salt is obtained by reaction of acid and base. So, our task is to decide whether carbon dioxide is acidic or basic in nature.

Complete answer:
We know that salt formation is taken only when an acid reacts with a base. We are given an equation:
${\text{Ca(OH}}{{\text{)}}_{\text{2}}}{\text{ + C}}{{\text{O}}_{\text{2}}} \to {\text{CaC}}{{\text{O}}_{\text{3}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$
Here we can see that carbon dioxide and calcium hydroxide react to form calcium carbonate.
We can clearly observe that calcium hydroxide is a base because it can furnish ${\text{O}}{{\text{H}}^{\text{ - }}}$ ion in an alkaline medium. This indicates the nature of carbon dioxide is acidic.
Hence, the correct option is option (A).

Note:
We have the notion that the taste of salt is salty. But this is not true. The taste depends upon the product from which it is made. It has basically five taste which includes salty (as in case of sodium chloride), sweet (as in the case of lead diacetate which is poisonous), sour (as in case of potassium bitartrate), bitter (as in case of magnesium sulphate) and savory (as in the case of monosodium glutamate).
Salts are normally insulators and have high melting points. Most of the salt is odourless with exception of having the smell of conjugate acid or conjugate base.