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Alkanes

Complete and incomplete combustion of alkanes

  • 3 things to know
  • Unit AS 2

Overview

Appearance of the flame when an alkane burns completely and appearance of the flame when an alkane burns incompletely.

What you need to know

Answer each one before you reveal it.

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Key term

Which two products are always formed when an alkane burns completely?

Key term

What condition is needed for the complete combustion of an alkane?

Key term

Write the equation for the complete combustion of methane.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Which two products are always formed when an alkane burns completely?

    Model answer

    Complete combustion of an alkane always gives carbon dioxide and water.

  2. 2

    What condition is needed for the complete combustion of an alkane?

    Model answer

    A plentiful supply of oxygen, normally an excess of air, is needed so that every carbon atom can be fully oxidised.

  3. 3

    Write the equation for the complete combustion of methane.

    Model answer

    The equation is CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l).

  4. 4

    Write the equation for the complete combustion of ethane.

    Model answer

    The equation is 2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l).

  5. 5

    Write the equation for the complete combustion of propane.

    Model answer

    The equation is C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l).

  6. 6

    Write the equation for the complete combustion of butane.

    Model answer

    The equation is 2C₄H₁₀(g) + 13O₂(g) → 8CO₂(g) + 10H₂O(l).

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