Question

Nitya took two test tubes A and B. In test tube A she put 10 mL of dilute NaOH and in test tube B she put 10

mL of dilute HCl. Write the changes observed in both the test tubes on adding a pinch of sodium carbonate

and also write the chemical reaction involved.​

Answer 1

Given:

Nitya took two test tubes A and B. In test tube A she put 10 mL of dilute NaOH and in test tube B she put 10 mL of dilute HCl.

To find:

Changes observed in both the test tubes after adding a pinch of sodium carbonate.

Solution:

Test Tube A:

• Na2CO3 (Sodium Carbonate) is a salt of weak acid and strong base. Hence , in aqueous solutions , it behaves like a base due to presence of excess OH- ions.

• After addition of sodium carbonate to this test tube, no such changes are observed.

• This is because , one base doesn't react with another base.

Test Tube B:

• After addition of sodium carbonate to this test tube, rising bubbles are observed in the solution due to release of carbon dioxide.

• The reaction between hydrochloric acid and sodium carbonate goes as follows :

$\boxed{\sf{2HCl + Na_{2}CO_{3} \rightarrow 2NaCl + H_{2}O + CO_{2}(\uparrow)}}$

Refer to attached photo for Tube B.