Question

A student did an activity in which he added sodium bicarbonate to hydrochloric acid. It forms the carbon dioxide gas. The gas released is passed through lime water. What change will be observed in lime water

1. Bubbles are formed
2. white precipitate is formed
3, the solution becomes colorless
4. the colour of solution becomes red.

Answer 1

A white precipitate is formed when carbon dioxide gas is passed through lime water.

Explanation:

• According to this reaction, sodium bicarbonate reacts with dilute hydrochloric acid and forms sodium chloride and carbon dioxide.

                    $Na_2CO_3\;(s)+2HCl\;(aq)\rightarrow2NaCl\;(aq)+CO_2\;(g)+H_2O\;(l)$

• Now, the $CO_{2}$ released is passed through lime water.

• The released $CO_{2}$ is in the form of brisk effervescence.

• Now, the released $CO_{2}$ is passed through lime water, it turns the lime water milky (i.e white precipitate is formed)

• The white precipitate formed is called calcium carbonate ($CaCO_{3}$)

                      $Ca(OH)_2\;+\;CO_2\;\rightarrow\;CaCO_3\;+\;H_2O$