Combustion starter|Organic chemistry fuels|KS4 Chemistry|Teachit - Free Printable

Let's solve each part of this Combustion Starter worksheet step by step.

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Task 1: Match up these half sentences

We need to match the left-hand side with the correct ending from the right-hand side.

| Left Side | Right Side |
|---------|----------|
| Combustion is the scientific | word for burning. |
| For combustion to occur | you need oxygen. |
| Incomplete combustion occurs | when there is not much oxygen. |
| Complete combustion produces | carbon dioxide and water. |
| Incomplete combustion produces | carbon monoxide and water. |

✔ Explanation:
- "Combustion" literally means burning, so it’s the scientific term.
- Oxygen is essential for combustion to happen.
- When oxygen is limited, incomplete combustion happens.
- Full (complete) combustion of hydrocarbons gives CO₂ and H₂O.
- With limited oxygen, CO (carbon monoxide) forms instead of CO₂.

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Task 2: Finish these word equations (Complete Combustion)

In complete combustion, a hydrocarbon reacts with oxygen to produce carbon dioxide and water.

#### a. methane + oxygen → carbon dioxide + water
✔️ Methane (CH₄) burns in oxygen to give CO₂ and H₂O.

#### b. ethane + oxygen → carbon dioxide + water
✔️ Ethane (C₂H₆) also undergoes complete combustion to form CO₂ and H₂O.

#### c. hexane + oxygen → carbon dioxide + water
✔️ Hexane (C₆H₁₄) is a hydrocarbon; complete combustion yields CO₂ and H₂O.

> 🔁 All hydrocarbons follow the general pattern:
> Hydrocarbon + Oxygen → Carbon Dioxide + Water

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Task 3: Fill in the gaps using the words provided

Words available:
incomplete, complete, oxygen, more, less, carbon, poisonous

#### a. Incomplete combustion produces more soot than complete combustion.
✔️ Because not all carbon burns completely, some remains as soot (unburned carbon).

#### b. Soot is unburned carbon.
✔️ Soot is solid carbon particles formed when fuel doesn’t burn fully.

#### c. Complete combustion releases more heat than incomplete combustion.
✔️ More energy is released when all the fuel is fully oxidized.

#### d. Carbon monoxide is a poisonous gas.
✔️ CO binds to hemoglobin in blood and prevents oxygen transport — very dangerous.

#### e. Complete combustion does not produce poisonous carbon monoxide.
✔️ Only incomplete combustion produces CO due to lack of oxygen.

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✔ Final Answers:

#### Task 1: Matching
- Combustion is the scientific → word for burning.
- For combustion to occur → you need oxygen.
- Incomplete combustion occurs → when there is not much oxygen.
- Complete combustion produces → carbon dioxide and water.
- Incomplete combustion produces → carbon monoxide and water.

#### Task 2: Word Equations
a. methane + oxygen → carbon dioxide + water
b. ethane + oxygen → carbon dioxide + water
c. hexane + oxygen → carbon dioxide + water

#### Task 3: Fill in the Gaps
a. more
b. carbon
c. more
d. poisonous
e. complete

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This worksheet helps reinforce understanding of combustion, especially the difference between complete and incomplete combustion and their environmental and safety implications.