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Question

Coal can be converted to clean-burning synthetic natural gas.

Automobile companies use hydrogen as an alternative to fossil fuels. Some properties of fuels are shown.

Formulate equation(s) for the conversion of coal and steam to methane.

[1]

Comment on the specific energies of hydrogen and methane.

[1]

Calculate the mass, in kg, of carbon dioxide produced by the complete combustion of 72.0 dm³ octane, C₈H₁₈.

Density of C₈H₁₈= 703 g dm⁻³

C₈H₁₈ (l) + 12.5O₂ (g) → 8CO₂ (g) + 9H₂O (g)

[2]

ALTERNATIVE 1:

2C (s) + 2H₂O (g) → CH₄ (g) + CO₂ (g) ✔

ALTERNATIVE 2:

C (s) + 2H₂O (g) → CO (g) + H2 (g) AND 3H₂ (g) + CO (g) → CH₄ (g) + H₂O (g) ✔

Accept “3C (s) + 2H₂O (g) → CH₄ (g) + 2CO (g)”.

« $\frac{{141.6}}{{55.5}}$ » hydrogen/H₂ produces 2.6 times/more than twice the energy of methane/CH₄ «per mass/g»

less mass of hydrogen/H₂ required «to produce same amount of energy»

hydrogen/H₂ more energy efficient ✔

Accept “hydrogen/H₂ produces «nearly» three times more energy than methane/CH₄ «per mass/g»”.

m_octane «= 72.0 dm³ × 703 g dm^–3» = 5.06 × 10⁴ «g»/50.6 «kg» ✔

m_{carbon dioxide} «= $\frac{{8 \times 44.01}}{{114.26}} \times 50.6$ » = 156 «kg» ✔

Award [2] for correct final answer.

[N/A]