Activity 2.1 class 10 science – Finding the nature of solutions using indicators

Activity 2.1 – Finding the nature of solutions using indicators

Activity 2.1 – Finding the nature of solutions using indicators

Objective:

To test the nature (acidic, basic or neutral) of various substances using different indicators.

Materials Required:

• Test tubes
• Dropper
• Solutions of:
  • Lemon juice
  • Vinegar
  • Baking soda solution
  • Soap solution
• Indicators:
  • Litmus paper (red and blue)
  • Phenolphthalein
  • Methyl orange

Procedure:

1. Take small amounts of each solution in separate test tubes.
2. Test each solution with:
   • Red and blue litmus paper
   • Phenolphthalein solution
   • Methyl orange solution

Activity 2.1 – Finding the nature of solutions using indicators

Observations:

Substance	Red Litmus	Blue Litmus	Phenolphthalein	Methyl Orange	Nature of Solution
Lemon juice	No change	Turns red	Colourless	Red	Acidic
Vinegar	No change	Turns red	Colourless	Red	Acidic
Baking soda solution	Turns blue	No change	Pink	Yellow	Basic
Soap solution	Turns blue	No change	Pink	Yellow	Basic

Conclusion:

• Acidic substances turn blue litmus red, and keep red litmus unchanged.
• Basic substances turn red litmus blue, and keep blue litmus unchanged.
• Phenolphthalein gives pink color in bases and remains colorless in acids.
• Methyl orange turns red in acids and yellow in bases.

Frequently ask Question answer

Q1. What is the aim of Activity 2.1?

Answer:
To test the nature of different solutions (acidic or basic) using various indicators like litmus, phenolphthalein, and methyl orange.

Q2. What are the different indicators used in this activity?

Answer:
The indicators used are:

1. Red and blue litmus paper
2. Phenolphthalein
3. Methyl orange

Q3. What happens when blue litmus paper is dipped in lemon juice?

Answer:
Blue litmus paper turns red, showing that lemon juice is acidic.

Q4. What change is observed when red litmus paper is dipped in soap solution?

Answer:
Red litmus paper turns blue, showing that soap solution is basic.

Q5. What color does phenolphthalein show in an acidic and basic solution?

Answer:

• In acidic solution → Colorless
• In basic solution → Pink

Q6. What color does methyl orange show in acids and bases?

Answer:

• In acidic solution → Red
• In basic solution → Yellow

Q7. Which substances tested in this activity are acidic in nature?

Answer:

• Lemon juice
• Vinegar

Q8. Which substances tested are basic in nature?

Answer:

• Baking soda solution
• Soap solution

Q9. Why are indicators used in this activity?

Answer:
Indicators are used to identify whether a substance is acidic or basic by showing a visible color change.

Q10. What conclusion do you draw from Activity 2.1?

Answer:
Acids and bases can be distinguished using indicators.

• Acids turn blue litmus red.
• Bases turn red litmus blue.
• Different indicators show characteristic color changes in acidic and basic media.

Activity 2.1 – Finding the nature of solutions using indicators

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