Respiration Experiment (Class 9 Science & Class 10 Science)
Introduction & Concept
Respiration is the biochemical process by which cells convert glucose and oxygen into usable energy (ATP). During this process, carbon dioxide and water are released as by-products. Studying respiration helps us understand how living organisms obtain energy for growth, movement, and all vital functions.
Experiment Details
Objective: To demonstrate the higher concentration of carbon dioxide in exhaled air compared to ambient air using lime water.
Materials
- Two clean test tubes
- Freshly prepared lime water (saturated calcium hydroxide solution)
- A syringe or pichkari
- Stopwatch or timer
Procedure
- Setup A (Exhaled Air):
- Pour lime water into Test Tube A.
- Have a person blow steadily through a glass tube or straw into the lime water for a fixed duration.
- Start the timer as they begin to blow.
- Setup B (Ambient Air):
- Pour fresh lime water into Test Tube B.
- Using a syringe or pichkari, draw in ambient air and bubble it through the lime water at the same rate.
- Time how long it takes to observe any change.
Observations
- Test Tube A: Lime water turns milky in approximately 15 seconds, indicating the rapid formation of calcium carbonate due to high COâ‚‚ concentration.
- Test Tube B: Lime water turns milky more slowly (around 45–60 seconds), showing a lower CO₂ concentration in ambient air.
| Tube | Air Source | Time to Turn Milky | COâ‚‚ Level |
|---|---|---|---|
| A | Exhaled Air | 15 s | High |
| B | Ambient Air | 45–60 s | Low |
Chemical Reaction
Calcium hydroxide (lime water) reacts with carbon dioxide to form calcium carbonate (insoluble) and water:
Ca(OH)₂ + CO₂ → CaCO₃ ↓ + H₂O
Real-Life Applications
- Respiration tests in biology to confirm COâ‚‚ exhalation.
- Greenhouse gas studies, monitoring COâ‚‚ exchange in plants.
- Medical diagnostics, measuring exhaled COâ‚‚ to assess respiratory health.
Detailed Explanation
Respiration occurs in all living cells, from simple bacteria to complex multicellular organisms. It consists of two main stages:
- Glycolysis – Glucose breaks down into pyruvate in the cytoplasm, yielding ATP and NADH.
- Aerobic Respiration – In the mitochondria, pyruvate enters the Krebs cycle and electron transport chain, producing the bulk of ATP and releasing CO₂ and H₂O.
By comparing how quickly lime water turns milky in the two setups, students directly observe that exhaled air contains significantly more COâ‚‚ than ambient air, proving the role of respiration in gas exchange.
Dencity & Virtual Science Lab
With the Dencity virtual lab, performing this Respiration Experiment becomes cost-efficient, safe, and highly interactive:
- Real-Time Simulation: Virtually bubble air samples through digital lime water and watch the turbidity change instantly.
- Step-by-Step Guidance: On-screen prompts guide students through each stage, reinforcing theoretical concepts with interactive learning.
- Data Logging: Automatically record time and COâ‚‚ levels, exportable for reports.
- Repeatability: Run unlimited trials without consuming reagents or risking spills.
Dencity for Teachers
| Feature | Benefit |
|---|---|
| Interactive Teaching | Assign control of the virtual experiment to students in real time, fostering interactive teaching and engagement. |
| Homework & Tracking | Create assignments on science experiments and monitor submissions instantly. |
| Virtual Classroom | Host live demos, discussions, and group problem-solving remotely. |
| Customizable Parameters | Adjust COâ‚‚ concentration, bubble rate, and observation time on the fly. |
| Automated Assessment | Built-in quizzes and instant feedback save grading time. |
Dencity virtual lab is fully optimized for interactive touch panels in classrooms, enabling smooth gestures for adjusting flow rate, starting/stopping timers, and annotating observations.
For customized pricing or a live demo, educational institutions can contact us at info@dencityapp.in.
Frequently Asked Questions
- Why does lime water turn milky with COâ‚‚?
Because calcium carbonate precipitates out of solution when COâ‚‚ reacts with calcium hydroxide. - Can this experiment run without lime water?
No; lime water is specific for detecting COâ‚‚ via precipitation. - What factors affect the rate of milky formation?
Bubble rate, COâ‚‚ concentration, temperature, and lime water saturation. - Is this experiment safe for students?
Yes, especially in the virtual science lab, where there’s no contact with chemicals. - How does Dencity help with science lab management?
It eliminates reagent costs, reduces setup time, and prevents hazards. - Can I export data from the virtual experiment?
Yes—downloadable CSV reports include time stamps and CO₂ levels. - Does Dencity support offline use?
The dencity app works on Android, iOS, and Desktop; some features are available offline. - Which classes is this experiment suitable for?
It’s ideal for class 9 science and class 10 science curricula. - How realistic are the virtual simulations?
Dencity uses high-fidelity physics models to match real-world outcomes. - Can I integrate Dencity with my school’s LMS?
Yes—Dencity offers APIs for seamless integration with popular learning management systems.
