Fueling Life
See how respiration releases energy from food and oxygen.
What this lesson covers
Why it matters
Your body is a slow-burning engine, turning food into motion without a single spark. This invisible fire keeps you warm and alive.
The idea in plain words
Verify the balance: 6 carbons, 12 hydrogens, and 18 oxygens on both sides.
Predict first
When your cells 'burn' glucose with oxygen, what waste gases are released?
Respiration is slow combustion: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O. You exhale CO₂ and produce water.
- Oxygen and water vapor
- Carbon dioxide and water — correct
- Nitrogen and heat
- Only carbon dioxide
What you do
Balance the equation. Add glucose and oxygen to the left, then match the carbon, hydrogen, and oxygen atoms on the right.
Check yourself
Why is respiration called 'slow combustion'?
Chemically, respiration matches combustion: fuel + O₂ → CO₂ + H₂O + Energy. The difference is speed and control.
In the equation C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O, what does the '6' before O₂ mean?
Coefficients in chemical equations represent the ratio of molecules (or moles) reacting, not mass.
Which observation proves respiration is a chemical change?
A chemical change is defined by the formation of new substances with different properties, here CO₂ and H₂O.
- It produces fire and smoke
- It releases energy, CO₂, and water, just like burning — correct
- It happens only in lungs
- 6 grams of oxygen
- 6 molecules of oxygen are needed for every 1 glucose molecule — correct
- Oxygen is 6 times heavier than glucose
- The body gets tired
- New substances (CO₂ and H₂O) are formed — correct
- The food changes color