This question is about combustion of fuels. Some central heating boilers use wood as a fuel. Suggest two reasons why wood is more sustainable than natural gas as a fuel for central heating boilers. 1 2 Natural gas is mainly methane. When methane burns it can produce both carbon monoxide and carbon dioxide. Explain the process by which carbon monoxide can be produced when methane is burned. Balance the equation for the combustion of methane to produce carbon monoxide. ___ CH₄(g) + ___ O₂(g) → ___ CO(g) + ___ H₂O(l) Propane burns to form carbon dioxide and water. The equation for the reaction is: C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l) 3.60 dm³ carbon dioxide is produced when a sample of propane is burned in 7.25 dm³ oxygen. Calculate the volume of unreacted oxygen. Give your answer in cm³

GCSE AQA Chemistry Measurement, Mass & Equations: This question is about combustio

This question is about combustion of fuels - AQA - GCSE Chemistry - Question 5 - 2019 - Paper 2

Question 5

This question is about combustion of fuels. Some central heating boilers use wood as a fuel. Suggest two reasons why wood is more sustainable than natural gas as a... show full transcript

Worked Solution & Example Answer:This question is about combustion of fuels - AQA - GCSE Chemistry - Question 5 - 2019 - Paper 2

Step 1

Suggest two reasons why wood is more sustainable than natural gas as a fuel for central heating boilers.

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Answer

Wood is renewable, meaning it can be replenished naturally over time, while natural gas is finite and will eventually run out.
When burned, wood is carbon-neutral because it releases the same amount of carbon dioxide that was absorbed during its growth, whereas burning natural gas adds to the overall carbon dioxide in the atmosphere.

Step 2

Explain the process by which carbon monoxide can be produced when methane is burned.

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Answer

Carbon monoxide is produced when there is not enough oxygen for complete combustion of methane. In a limited oxygen environment, the reaction can be represented as:

$CH₄ + O₂ ⇌ CO + H₂O$

This incomplete combustion process leads to the formation of carbon monoxide instead of carbon dioxide.

Step 3

Balance the equation for the combustion of methane to produce carbon monoxide.

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Answer

The balanced equation for the incomplete combustion of methane is:

$2CH₄(g) + 3O₂(g) → 2CO(g) + 4H₂O(l)$

Step 4

Calculate the volume of unreacted oxygen.

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Answer

First, we need to determine the amount of oxygen required for the complete combustion of the given propane equation:

From the reaction, 5 dm³ of O₂ is needed for every 1 dm³ of C₃H₈.

For 3.60 dm³ of CO₂ produced, the oxygen used is:

$ext{Oxygen needed} = rac{3 ext{ CO}_2}{1 ext{ C}_3H_8} imes 5 ext{ O}_2 = 6.0 ext{ dm}^3$

Given that 7.25 dm³ of oxygen was available:

$ext{Unreacted oxygen} = 7.25 ext{ dm}^3 - 6.0 ext{ dm}^3 = 1.25 ext{ dm}^3$

Converting this to cm³ gives:

$1.25 ext{ dm}^3 imes 1000 = 1250 ext{ cm}^3$

This question is about combustion of fuels - AQA - GCSE Chemistry - Question 5 - 2019 - Paper 2

Worked Solution & Example Answer:This question is about combustion of fuels - AQA - GCSE Chemistry - Question 5 - 2019 - Paper 2

Suggest two reasons why wood is more sustainable than natural gas as a fuel for central heating boilers.

Explain the process by which carbon monoxide can be produced when methane is burned.

Balance the equation for the combustion of methane to produce carbon monoxide.

Calculate the volume of unreacted oxygen.

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