AIM :

Studying the properties of bases (NaOH) by their reaction with


(i) Litmus solution (Blue/Red)


(ii) Zinc metal (Zn)


(iii) Solid sodium carbonate (Na2CO3)

MATERIALS REQUIRED:


Apparatus: Test tubes, test tube holder, test tube stand and droppers.


Chemical compounds : Dil. NaOH, red and blue litmus solutions, zinc metal, sodium carbonate


THEORY:


1. NaOH is a base. Bases turn red litmus blue and do not affect blue litmus.


2. On reacting with zinc metal, NaOH forms sodium zincate, and hydrogen gas is liberated. The hydrogen gas burns with a pop sound.



3. NaOH does not react with solid or aqueous Ha2CO3.


PROCEDURE :


1. Litmus test: Take about 1 mL of NaOH in two test tubes and mark them as ‘A’ and ‘B.’ Put both the test tubes in a test tube stand. Now, add blue litmus in a test tube ‘A’ and red litmus in a test tube ‘B. and note the observation in observation table


2. Reaction with Zn metal: Take a test tube and zinc granules to it. Add NaOH solution to it and place a cork with a fine jet on the mouth of the test tube. Bring a lighted matchstick near the mouth of the fine jet and observe the mouth of the fine jet and observe. note the observation in observation table


3. Na2CO3 test :Take a small amount of sodium carbonate in a test tube and add sodium hydroxide solution. note the observation in observation table


OBSERVATION TABLE :


S.No



Test



Observation



Inference



1



Litmus test



Red litmus turns blue.


No change in the colour of blue litmus.



NaOH has basic character.



2



Reaction with Zn metal



Bubbles of hydrogen gas are formed, and gas evolves.


A pop sound is obtained.



Zn reacts with dil. NaOH and liberates hydrogen gas.



3



Na2CO3 test



No change is observed.



NaOH does not react with Na2CO3.



RESULT:


1. NaOH turns red litmus blue.


2. On reaction with Zn metal, it releases H2 gas.


3. It does not react with Na2CO3.


PRECAUTIONS :


1. Handle NaOH with care.


2. Use small quantities of the chemical.


3. A fine jet should be taken for burning hydrogen.


4. Zn granules should be clean.


5. Wash your hands properly after completing the experiment.


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