Question

When a gas ‘A’ is passed through a solution of calcium hydroxide, a white ppt is formed. The student continue to pass ‘A’ and observed that white ppt formed is disappeared by forming another substance ‘C’. Identify ‘A’ and ‘C’.
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Answer 1

Answer:

: Milkiness disappear when carbon dioxide is passed through lime water in excess because calcium bicarbonate is soluble in water, thus it dissolves

Answer 2

Given:

When a gas ‘A’ is passed through a solution of calcium hydroxide, a white ppt is formed. The student continue to pass ‘A’ and observed that white ppt formed is disappeared by forming another substance ‘C’.

To find:

Substance A and C.

Solution:

Gas A is carbon dioxide (CO2).

• This is because when carbon dioxide is passed through a solution of calcium hydroxide white precipitate of calcium carbonate is formed which settles at the bottom of the test tube.

$\boxed{CO_{2}+Ca(OH)_{2}\rightarrow CaCO_{3}+H_{2}O}$

Substance C is Calcium-Bicarbonate.

• Now , when the student kept on passing carbon dioxide through the solution the white precipitate disappear due to formation of of calcium bicarbonate which is soluble.

$\boxed{CaCO_{3}+CO_{2}+H_{2}O\rightarrow Ca(HCO_{3})_{2}}$

So, A is CO2 and B is Ca(HCO3)2.