Class 10th Science Lab Manual CBSE Solution
Lab Experiment 8Viva Questions- Mention the changes when acetic acid is added to distilled water and sodium hydrogen…
- Why does lime water turn milky when reacted with CO2?
- Mention two uses of acetic acid.
- Which test signifies the acidic nature of acetic acid?
- Why is acetic acid categorised as a weak acid?
- How will you test if the gas liberated is CO2 or not?
- Do you find use of acetic acid in day-to-day life? If yes, where?…
- Mention two physical properties of acetic acid.
- What happens when a few drops of acetic acid are added to a test tube containing…
- What is vinegar?
- What is the name of pure acetic acid?
- Is acetic acid miscible in water?
- Can acetic acid be produced naturally? How?
- State the medical uses of acetic acid.
- Describe the corrosive and flammable nature of acetic acid.
- Mention the changes when acetic acid is added to distilled water and sodium hydrogen…
- Why does lime water turn milky when reacted with CO2?
- Mention two uses of acetic acid.
- Which test signifies the acidic nature of acetic acid?
- Why is acetic acid categorised as a weak acid?
- How will you test if the gas liberated is CO2 or not?
- Do you find use of acetic acid in day-to-day life? If yes, where?…
- Mention two physical properties of acetic acid.
- What happens when a few drops of acetic acid are added to a test tube containing…
- What is vinegar?
- What is the name of pure acetic acid?
- Is acetic acid miscible in water?
- Can acetic acid be produced naturally? How?
- State the medical uses of acetic acid.
- Describe the corrosive and flammable nature of acetic acid.
Lab Experiment 8
Question 1.AIM
To study or the following properties or acetic acid (ethanoic acid):
(i) Odour
(ii) Solubility in water
(iii) Effect on litmus
(iv) Reaction with sodium hydrogen carbonate
Answer:MATERIALS REQUIRED
Glass rod, acetic acid, litmus paper, sodium bicarbonate, test tubes, water, test tube stand, lime water.
THEORY
(i) Acetic acid is an organic acid, its 5-8% concentrated solution is called vinegar.
(ii) It is a weak acid. It ionises partially in presence of water as shown below:
CH3COOH + H2O ⇋ CH3COO-(aq) + H2O+(aq)
(iii) Acetic acid has pH <7, hence It turns blue litmus red.
(iv) It is completely soluble in water.
(v) It reacts with sodium bicarbonate to liberate CO2, which turns lime water milky and the milkiness disappears if an excess of CO2 is passed through the solution.
PROCEDURE
1. Odour
Take a small amount of acetic acid in a test tube.
2.Solubility in water
Take 2 mL of water in a test tube and add a few drops of acetic acid. Shake the test tube carefully.
3.Effect on litmus
Take a strip of blue litmus paper and add one drop of acetic solution on the blue litmus paper.
Take a red litmus paper and add one drop of acetic acids solution on red litmus paper.
4.Reaction with sodium bicarbonate
Take 5 mL of acetic acid in a test tube and add sodium bicarbonate.
Pass the evolving gas through lime water.
OBSERVATIONS
RESULT
1. Acetic acid has a pungent odour.
2. Acetic acid is completely soluble in water i.e. acetic acid and water form a true solution.
3. Acetic acid having a pH <7 turns blue litmus paper red.
4. Acetic acid does not change the colour of blue litmus paper.
5. CO2 gas is liberated when it reacts with sodium bicarbonate.
PRECAUTIONS
1. Do not inhale vapours of acetic acid directly.
2. Ethanoic acid should be handled with care.
3. Freshly prepared lime water solution should be used.
AIM
To study or the following properties or acetic acid (ethanoic acid):
(i) Odour
(ii) Solubility in water
(iii) Effect on litmus
(iv) Reaction with sodium hydrogen carbonate
Answer:
MATERIALS REQUIRED
Glass rod, acetic acid, litmus paper, sodium bicarbonate, test tubes, water, test tube stand, lime water.
THEORY
(i) Acetic acid is an organic acid, its 5-8% concentrated solution is called vinegar.
(ii) It is a weak acid. It ionises partially in presence of water as shown below:
CH3COOH + H2O ⇋ CH3COO-(aq) + H2O+(aq)
(iii) Acetic acid has pH <7, hence It turns blue litmus red.
(iv) It is completely soluble in water.
(v) It reacts with sodium bicarbonate to liberate CO2, which turns lime water milky and the milkiness disappears if an excess of CO2 is passed through the solution.
PROCEDURE
1. Odour
Take a small amount of acetic acid in a test tube.
2.Solubility in water
Take 2 mL of water in a test tube and add a few drops of acetic acid. Shake the test tube carefully.
3.Effect on litmus
Take a strip of blue litmus paper and add one drop of acetic solution on the blue litmus paper.
Take a red litmus paper and add one drop of acetic acids solution on red litmus paper.
4.Reaction with sodium bicarbonate
Take 5 mL of acetic acid in a test tube and add sodium bicarbonate.
Pass the evolving gas through lime water.
OBSERVATIONS
RESULT
1. Acetic acid has a pungent odour.
2. Acetic acid is completely soluble in water i.e. acetic acid and water form a true solution.
3. Acetic acid having a pH <7 turns blue litmus paper red.
4. Acetic acid does not change the colour of blue litmus paper.
5. CO2 gas is liberated when it reacts with sodium bicarbonate.
PRECAUTIONS
1. Do not inhale vapours of acetic acid directly.
2. Ethanoic acid should be handled with care.
3. Freshly prepared lime water solution should be used.
Viva Questions
Question 1.Mention the changes when acetic acid is added to distilled water and sodium hydrogen carbonate powder.
Answer:(a) When acetic acid is reacted with distilled water, it gets dissolved in distilled water forming a homogeneous transparent solution.
(b) When acetic acid is reacted with sodium hydrogen carbonate powder, brisk effervescence due to CO2 gas is observed.
Question 2.Why does lime water turn milky when reacted with CO2?
Answer:On reacting lime water with CO2, it turns milky due to formation of insoluble white precipitate of calcium carbonate.
Question 3.Mention two uses of acetic acid.
Answer:Acetic acid is used:
(a) In manufacture of rayon fibre.
(b) as coagulant in the manufacture of rubber.
Note: coagulant- a substance/ agent which is added to thicken a mixture.
Question 4.Which test signifies the acidic nature of acetic acid?
Answer:Litmus test helps in proving the acidic nature of acetic acid as it turns blue litmus red and does not affect red litmus paper.
Question 5.Why is acetic acid categorised as a weak acid?
Answer:Acetic acid doesn’t dissociate much in solution. It partially ionizes in water which means not all of its molecules break up into positive and negative ions when dissolved in water.
Question 6.How will you test if the gas liberated is CO2 or not?
Answer:It can be tested by lime water test. The gas is allowed to pass through lime water and if it turns milky, then the liberated gas is CO2.
Question 7.Do you find use of acetic acid in day-to-day life? If yes, where?
Answer:Yes, acetic acid is used as a preservative. It preserves food products for longer use.
Question 8.Mention two physical properties of acetic acid.
Answer:Two physical properties of acetic acid are:
(a) It has a vinegar like smell.
(b) It is soluble in water.
Question 9.What happens when a few drops of acetic acid are added to a test tube containing phenolphthalein?
Answer:When a few drops of acetic acid are added to a test tube containing phenolphthalein, the phenolphthalein remains colourless due to the acidic medium.
Note: Phenolphthalein is an indicator which turns colourless in acidic media and pinkish red in basic media.
Question 10.What is vinegar?
Answer:Vinegar is 5-8 % aqueous solution of acetic acid. It is used to add flavour to food and also used as a preservative.
Question 11.What is the name of pure acetic acid?
Answer:Pure acetic acid is known as glacial acetic acid. It is undiluted acetic acid.
Question 12.Is acetic acid miscible in water?
Answer:Yes, acetic acid is miscible in water in all proportions. Its miscibility makes it a useful industrial chemical.
Question 13.Can acetic acid be produced naturally? How?
Answer:Acetic acid is prepared naturally by bacterial fermentation. These bacteria are found in foodstuffs, soil, etc.
Question 14.State the medical uses of acetic acid.
Answer:Some of the medical uses of acetic acid are as follows:
(a) It is used as an antiseptic.
(b) It is used in screening of some cancers.
(c) It can also be used to treat cancers.
Question 15.Describe the corrosive and flammable nature of acetic acid.
Answer:Acetic acid is corrosive to some metals to metals like iron, zinc, magnesium, etc. It can become flammable at temperatures exceeding 39o C.
Mention the changes when acetic acid is added to distilled water and sodium hydrogen carbonate powder.
Answer:
(a) When acetic acid is reacted with distilled water, it gets dissolved in distilled water forming a homogeneous transparent solution.
(b) When acetic acid is reacted with sodium hydrogen carbonate powder, brisk effervescence due to CO2 gas is observed.
Question 2.
Why does lime water turn milky when reacted with CO2?
Answer:
On reacting lime water with CO2, it turns milky due to formation of insoluble white precipitate of calcium carbonate.
Question 3.
Mention two uses of acetic acid.
Answer:
Acetic acid is used:
(a) In manufacture of rayon fibre.
(b) as coagulant in the manufacture of rubber.
Note: coagulant- a substance/ agent which is added to thicken a mixture.
Question 4.
Which test signifies the acidic nature of acetic acid?
Answer:
Litmus test helps in proving the acidic nature of acetic acid as it turns blue litmus red and does not affect red litmus paper.
Question 5.
Why is acetic acid categorised as a weak acid?
Answer:
Acetic acid doesn’t dissociate much in solution. It partially ionizes in water which means not all of its molecules break up into positive and negative ions when dissolved in water.
Question 6.
How will you test if the gas liberated is CO2 or not?
Answer:
It can be tested by lime water test. The gas is allowed to pass through lime water and if it turns milky, then the liberated gas is CO2.
Question 7.
Do you find use of acetic acid in day-to-day life? If yes, where?
Answer:
Yes, acetic acid is used as a preservative. It preserves food products for longer use.
Question 8.
Mention two physical properties of acetic acid.
Answer:
Two physical properties of acetic acid are:
(a) It has a vinegar like smell.
(b) It is soluble in water.
Question 9.
What happens when a few drops of acetic acid are added to a test tube containing phenolphthalein?
Answer:
When a few drops of acetic acid are added to a test tube containing phenolphthalein, the phenolphthalein remains colourless due to the acidic medium.
Note: Phenolphthalein is an indicator which turns colourless in acidic media and pinkish red in basic media.
Question 10.
What is vinegar?
Answer:
Vinegar is 5-8 % aqueous solution of acetic acid. It is used to add flavour to food and also used as a preservative.
Question 11.
What is the name of pure acetic acid?
Answer:
Pure acetic acid is known as glacial acetic acid. It is undiluted acetic acid.
Question 12.
Is acetic acid miscible in water?
Answer:
Yes, acetic acid is miscible in water in all proportions. Its miscibility makes it a useful industrial chemical.
Question 13.
Can acetic acid be produced naturally? How?
Answer:
Acetic acid is prepared naturally by bacterial fermentation. These bacteria are found in foodstuffs, soil, etc.
Question 14.
State the medical uses of acetic acid.
Answer:
Some of the medical uses of acetic acid are as follows:
(a) It is used as an antiseptic.
(b) It is used in screening of some cancers.
(c) It can also be used to treat cancers.
Question 15.
Describe the corrosive and flammable nature of acetic acid.
Answer:
Acetic acid is corrosive to some metals to metals like iron, zinc, magnesium, etc. It can become flammable at temperatures exceeding 39o C.
