Opt Science Project Work

Investigating Colour Changes of Natural Indicators in Acids and Bases

1. Objectives

• To prepare natural indicators from commonly available plant materials.

• To observe colour changes in acidic and basic solutions.

• To compare the effectiveness of different natural indicators.

• To identify which natural indicators produce the most distinct colour changes.

2. Suggested Natural Indicators

Students should select at least five materials from the following list or can use other colorful flower or fruits.

1. Hibiscus

2. Turmeric (बेसार)

3. Red cabbage

4. Butterfly pea (अपराजिता)

5. Black grapes

6. Beetroot (चुकन्दर)

Students may also investigate other locally available coloured flowers, fruits, and leaves. Not all coloured extracts will be effective indicators.

3. Materials Required

• Five or more natural materials from the suggested list

• Lemon juice or vinegar (acid)

• Baking soda solution (base)

• Plain water

• Transparent glasses or test tubes

• Warm water, spoon and filter cloth

• Labels and notebook

4. Experimental Procedure

1. Collect at least five suggested natural materials.

2. Crush each material separately and extract its colour using a small amount of water. For turmeric, prepare a dilute yellow mixture.

3. Filter the extracts where necessary.

4. Label three test tubes or transparent glasses as Acid, Neutral and Base for each indicator.

5. Add equal quantities of lemon juice, plain water and baking soda solution to the respective glasses.

6. Add the same quantity of natural indicator to each glass.

7. Observe and record the colour changes.

8. Repeat the experiment for every natural indicator.

5. Observation Table

Students must complete this table based on their experiments. Do not fill in the expected colours before testing.

Natural indicator	Colour in acid	Colour in plain water	Colour in base
Hibiscus
Turmeric
Red cabbage
Butterfly pea
Black grapes
Beetroot

6. Questions for Analysis

1. Which natural indicator showed the most noticeable colour change?

2. Which indicators showed different colours in acidic and basic solutions?

3. Which natural indicator did not show a clear colour change?

4. How did turmeric behave differently from the other indicators?

5. Can all coloured plant extracts be used as acid–base indicators? Explain.

6. Which indicator would you recommend as an alternative to a laboratory indicator? Give reasons.

7. Conclusion

Write a short conclusion (100–150 words) explaining your experimental findings. Identify the most effective natural indicator and support your answer using the observed colour changes.

Report Format

INVESTIGATION OF COLOUR CHANGES OF NATURAL INDICATORS IN ACIDS AND BASES

A PROJECT WORK SUBMITTED FOR PARTIAL FULFILLMENT OF REQUIREMENT IN OPTIONAL SCIENCE CLASS 10

 

 

 

 

            

 

 

 

 

 

 

Submitted by:

[name of student]

Class:10

Section: …..

Roll no……

 

 

 

 

Submitted to :

[name of teacher]

            Department of Science

Mount View English Boarding school

      Ghorahi Dang

 

 

 

1. Introduction

Acids and bases are important chemical substances that we use in our daily lives. Lemon juice and vinegar are examples of acidic substances, whereas soap solution and baking soda solution are examples of basic substances.

An indicator is a substance that helps us distinguish between acids and bases by showing a change in colour.

Some natural materials obtained from plants can act as acid–base indicators. Their colours may change when they come into contact with acidic or basic solutions.

In this project, I investigated different natural materials to observe their colour changes in acids and bases and compare their effectiveness as indicators.

2. Objectives

The main objectives of this project were:

1. To prepare indicators from naturally available materials.
2. To observe their colours in acidic, neutral and basic solutions.
3. To compare the colour changes shown by different indicators.
4. To identify the most effective natural indicator among the tested materials.

3. Materials Required

The following materials were used for the experiment:

Natural materials:

• …………
• ………………..
• ……………….
• …………………
• ……………….
• ……………….

Other materials:

• Lemon juice
• Baking soda solution
• Dilute soap solution
• Plain water
• Transparent glasses
• Spoon
• Warm water
• Filter cloth

5. Experimental Procedure

Step 1: Preparation of natural indicators

Some natural materials: hibiscus, turmeric, ……………………………………… were collected.

Those plant materials were crushed separately and mixed them with a small quantity of warm water to extract their colours. The crushed material is filtered with the help of clean cloth and collected in different glass.

Step 2: Preparation of test solutions

Three types of solutions were prepared:

• Acidic solution: Lemon juice diluted with water
• Neutral comparison: Plain water
• Basic solution: Dilute soap solution / baking soda solution (write one which you have used)

Step 3: Testing the indicators

Three clean glasses were taken for each natural indicator and labelled them Acid, Neutral and Base.

Equal amounts of the respective solutions were poured into the glasses.

Then an equal quantity of natural indicator were added to each glass and carefully and colour changes was observed.

Observations was recorded in a table and results are compared.

 

6. Observations

Natural indicator	Acidic solution	Plain water	Basic solution
Hibiscus
Turmeric
………
………………
………………
……………

 

7. Analysis and Discussion

From the sample observations, it was found that different natural materials behaved differently in acidic and basic solutions.

Red cabbage showed a clear difference between acidic and basic conditions. Its extract appeared ………… in the acidic solution and ………… in the basic solution.

Hibiscus also showed noticeable colour changes. Its extract became ……… in the acidic solution and …………. in the basic solution.

………………….(write similar to all the indicators)

 

The experiment suggested that not all coloured natural materials are equally effective as acid–base indicators.

Some plant pigments change their molecular structure depending on the acidity or basicity of the solution. This can cause a visible colour change.

8. Results

Based on the illustrative observations, the following results were obtained:

1. , …… and ……….. showed clear differences between acidic and basic solutions.
2. ………………
3. ………………….
4. …………..
5. ……………………….. appeared to be the most effective indicator among the tested materials.

9. Precautions

The following precautions were taken during the experiment:

1. Clean and separate glasses were used for each indicator.
2. Approximately equal quantities of solutions and extracts were used to ensure consistency.
3. All containers were labelled correctly to avoid confusion.
4. Mixing of different indicators was avoided to prevent interference with the results.
5. Chemicals and plant extracts were not tasted during the experiment.
6. Only dilute household solutions were used, and the teacher's safety instructions were followed.
7. Colour changes were observed against a white background to make comparisons easier and more accurate.

10. Conclusion

In this project, six natural materials were investigated to study their behaviour in acidic and basic solutions.

The sample results showed that red cabbage, hibiscus and butterfly pea can act as useful natural acid–base indicators because they produce visible colour changes under different conditions.

Turmeric was also found to be useful, particularly for identifying sufficiently basic solutions. However, black grapes showed less distinct colour changes, while beetroot was not very effective under the tested conditions.

Among the materials investigated, red cabbage appeared to be the most effective natural indicator because it produced clearly distinguishable colours in acidic and basic solutions.

The investigation demonstrated that certain natural plant pigments can be used to distinguish between acids and bases. It also highlighted the importance of careful observation, systematic experimentation and evidence-based conclusions in scientific investigations.

 

11. Limitations of the Experiment

• The exact pH values of the solutions were not measured.
• The concentrations of natural extracts were not precisely controlled.
• Some colours were difficult to distinguish.
• The results might change when different basic solutions are used.
• The investigation did not determine how accurately each indicator could measure pH.

12. References

1. Class 10 Science and Technology textbook – Acids, Bases and Salts.
2. Observations recorded during the practical investigation.
3. …………………
4. …………….

(Students should list only the sources they actually used.)

---

13. Photographic Evidence

(Here insert the photograph taken during the experiment, it should show your face and the materials, glasses you have used)

If your report is hand written, print the photo and attach here.

Combination of resistors Practical

aSTUDY OF SERIES AND PARALLEL COMBINATION OF RESISTORS USING PHET SIMULATION Materials Required Phet Simulation – DC virtual LabApparatus/Components in the Simulation• Battery• Resistors• Wires• Switch• Ammeter• Voltmeter TheorySeries Combination of ResisitanceTwo or more resistances are said to be connected in series when they are connected end to end and the same current flows through each of them in turn. In this case, the equivalent or the total resistance equals the sum of the number of individual resistances present in the series combination. Mathematically, the equivalent resistance of any number of resistances (R1, R2, R3${\displaystyle R_1,R_2,R_3}$ Connected in series is given as:

Req = R1 + R2 + R 3 $$R_{eq}=R_1+R_2+R_3$$Parallel Combination of resistanceTwo or more resistances are said to be connected in parallel connected when they are connected between two points and each has a different current direction. The current is branched out and recombined as the branches intersect at a common point in such circuits. Mathematically, the equivalent resistance of any number of resistances ) connected in parallel is given as:

1

Req=1

R1+1

R2+1

R3$$\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}$$ProcedureFor series combination1. Open the PhET Circuit Construction Kit – DC Virtual Lab.2. Construct a circuit containing a battery, switch and two resistors connected in series.3. Use R₁ = 10 Ω, R₂ = 20 Ω and battery voltage V = 12 V.4. Close the switch. 5. Place the ammeter at different points in the circuit and record the current.6. Use the voltmeter to measure voltage across R₁, voltage across R₂, and total voltage across the combination.7. Calculate the theoretical equivalent resistance using Rs = R₁ + R₂.8. Calculate the theoretical current using I = V/Rs.9. Compare theoretical values with simulation values. For Parallel combination17. Construct a new circuit containing two resistors connected in parallel.18. Use R₁ = 10 Ω, R₂ = 20 Ω and battery voltage V = 12 V.19. Close the switch.20. Measure the total current supplied by the battery.21. Measure the current through R₁ and the current through R₂.22. Measure the voltage across each resistor.23. Calculate the theoretical equivalent resistance using 1/Rp = 1/R₁ + 1/R₂.24. Calculate the theoretical total current using I = V/Rp.25. Compare theoretical values with the simulation results.ObservationFor Series

Quantity	Observed Value
Resistance R₁	10 Ω
Resistance R₂	20 Ω
Battery voltage	12 V
Current before R₁	________ A
Current between R₁ and R₂	________ A
Current after R₂	________ A
Voltage across R₁	________ V
Voltage across R₂	________ V
Total voltag	_______ V
Equivalent resistance	________ Ω

For Parallel

Quantity	Observed Value
Resistance R₁	10 Ω
Resistance R₂	20 Ω
Battery voltage	12 V
Voltage across R₁	________ V
Voltage across R₂	________ V
Current through R₁	________ A
Current through R₂	________ A
Total current	________ A
Equivalent resistance R	________ Ω

CalculationSeries CombinationGiven: R₁ = 10 Ω, R₂ = 20 Ω, V = 12 Va. Equivalent resistance: Rs = R₁ + R₂ = __________b. Total current: I = V/Rs = __________c. Voltage across R₁: V₁ = IR₁ = __________d. Voltage across R₂: V₂ = IR₂ = __________ Parallel CombinationGiven: R₁ = 10 Ω, R₂ = 20 Ω, V = 12 Va. Equivalent resistance: 1/Rp = 1/10 + 1/20; Rp = __________b. Current through R₁: I₁ = V/R₁ = __________c. Current through R₂: I₂ = V/R₂ = __________d. Total current: I = I₁ + I₂ = __________ConclusionFor Series CombinationComplete the following statement based on your observations:When resistors are connected in series, the __________ remains the same through all the resistors, while the __________ is divided among the resistors. The equivalent resistance is equal to ______________________________.Therefore, the equivalent resistance of a series combination is ______ than the resistance of any individual resistor.For ParallelWhen resistors are connected in parallel, the ______ across each resistor remains the same, while the ______ divides among the different branches. The total current is equal to ______________________________.The equivalent resistance of a parallel combination is ______ than the resistance of the smallest individual resistor. Overall Conclusion Write your conclusion in your own words after completing the simulation.From the PhET simulation, I observed that in a series combination, ________________________________.The equivalent resistance of resistors in series is ________________________________.In a parallel combination, ________________________________.The equivalent resistance of resistors in parallel is ________________________________.Therefore, the simulation verifies that ________________________________.