Q. 1C4.5( 12 Votes )
Studying the properties of bases (NaOH) by their reaction with
(i) Litmus solution (Blue/Red)
(ii) Zinc metal (Zn)
(iii) Solid sodium carbonate (Na2CO3)
Apparatus: Test tubes, test tube holder, test tube stand and droppers.
Chemical compounds : Dil. NaOH, red and blue litmus solutions, zinc metal, sodium carbonate
Bases: Bases are the substance which furnishes hydroxide ions in a solution.
1. NaOH is a base. Base turn red litmus solution to blue and does not affect blue litmus solution.
2. On reacting with zinc metal, NaOH forms sodium zincate and hydrogen gas is liberated.
3. NaOH does not react with solid or aqueous Na2CO3.
1. Litmus test:
(i) Take about 5mL of NaOH in two test tubes and mark them as ‘A’ and ‘B.’ Put both the test tubes in a test tube stand.
(ii) Add blue litmus in a test tube ‘A’ and red litmus in a test tube ‘B.
(iii) Note the observation in the observation table.
2. Reaction with Zn metal:
(i) Take a test tube and zinc granules to it.
(ii) Add NaOH solution to it and place a cork with a fine jet on the mouth of the test tube.
(iii) Bring a lighted matchstick near the mouth of the fine jet and observe the mouth of the fine jet and observe.
(iv) Note the observation in the observation table.
3. Na2CO3 test:
(i) Take a small amount of sodium carbonate in a test tube and add sodium hydroxide solution.
(ii) Note the observation in the observation table.
OBSERVATION TABLE :
1. NaOH turns red litmus solution to blue and does not affect the blue litmus solution.
2. On reaction with Zn metal, Zn atom being more reactive undergo displacement reaction to form sodium zincate and H2 gas is liberated.
3. NaOH does not undergo a chemical reaction with Na2CO3.
1. NaOH is corrosive in nature, therefore use with care.
2. Use small quantities of the chemicals in the test tube.
3. A fine jet should be taken from the test tube for burning hydrogen.
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