Name: Reactions of Metal Carbonates with Acids
Uploaded: 2019-07-19
Duration: 4 min 6 s
Description: When substances like metals and liquids like acid react, it produces salt, water, and carbon dioxide. Here, in this video, it has been explained in detail wi...

Question

A metal carbonate $X$ on reacting with an acid gives a gas which when passed through a solution $Y$ gives the carbonate back. On the other hand, a gas $G$ that is obtained at anode during electrolysis of brine is passed on dry $Y$ , it gives a compound $Z$ , used for disinfecting drinking water. Identify $X, Y, G,$ and $Z .$

Accepted Answer

$X$ is calcium carbonate and the gas evolved is carbon dioxide, along with the production of calcium chloride.

${CaCO}_{3} + dil . 2 HCI \to {CaCI}_{2} + H_{2} O + {CO}_{2} ↑$

Solution $Y$ is lime water $Ca (OH)_{2}$ , because when ${CO}_{2}$ is passed through it, it gives the carbonate back as shown by the given equation.

$\begin{matrix} Ca (OH)_{2} + {CO}_{2} \\ Y \end{matrix} \begin{matrix} \to {CaCO}_{3} ↓ + H_{2} O \\ X \end{matrix}$

The gas evolved at anode during electrolysis of brine is chlorine $(G)$ . The process is used in industry and the name of the process is chlor-alkali process.

$\begin{matrix} \underset{Brine solution}{2 NaCI + 2 H_{2} O} \begin{matrix} \overset{Electrolysis}{\to} \end{matrix} \end{matrix} \begin{matrix} 2 NaOH + \underset{Chlorine gas}{{CI}_{2}} (g) + H_{2} (g) \end{matrix}$

When chlorine gas is passed through dry $Ca (OH)_{2} (Y),$ it produces bleaching powder $(Z)$ .

$Ca {(OH)}_{2} + \underset{\begin{matrix} Bleaching \\ powder (Z) \end{matrix}}{{CI}_{2} \to {CaOCl}_{2}} + H_{2} O$

Hence, $Z$ is calcium oxychloride $({CaOCl}_{2})$ or bleaching powder which is used for disinfecting drinking water.

Important Questions on Acids, Bases and Salts

Learn and Prepare for any exam you want !