Question

HEYE BRAINLIAN,





$\huge \fbox \red{❥ Question}$


A student dropped few pieces of marble in dilute hydrochloric acid, contained in a test-tube. The evolved gas was then passed through lime water. What change would be observed in lime water? What will happen if excess of gas is passed through lime water? With the help of balanced chemical equations for all the changes explain the observations.​

Answer 1

Answer:

Lime water turns milky due to the formation of white ppt of CaCO3 on passing excess CO2, milkiness disappears because Ca(HCO3)2 is formed which is soluble in water.

(i) Lime water will turn milky due to formation of calcium carbonate.

(ii) Ca(OH)2 (aq) + CO2 (g)→ Ca CO3 (s) + HaO(l)

Answer 2

$\sf \large \underbrace{ \underline{Answer+Explanation}}$

$\sf \large As \: we \: know \: that \: marble \: is \: made \: up \: of \: CaCO_3$

It means that the following reaction will take place when marble is dropped into Hydrochloric acid:-

$\sf CaCO_3+2HCl \longrightarrow \: CaCl_2+CO_2+H_2O$

Now it is obvious that Carbon dioxide gas will evolve when you add marble in Hydrochloric acid.

Formula of Lime water (Calcium hydrogen) is Ca(OH)2.

When it reacts with Carbon dioxide following reaction will take place:-

$\sf CO_2+Ca(OH)_2 \longrightarrow CaCO_3+H_2O$

$\sf Here \: CaCO_3 \: is \: a \: white \: precipitate.$

This carbon dioxide gas is responsible for the turning of lime water milky.

Now when excess carbon dioxide gas is passed through this solution the precipitate will dissolve and form a colourless solution.See the following reaction:-

$\sf CaCO_3+H_2O+CO_2 \longrightarrow Ca(HCO)_3$

Here in the product side calcium hydrogen carbonate is formed which is a transparent solution.