19. Which of the following chemical equations represents

propane combusts?

A. 2 CsHe (g) + 5O2 (g) → 3C02 (g) + 4H20 (1)

B. 2 CsHe (g) + 5O2 (g) → 3CO2 (g) + 3H20 (1

C. CsHe (g) + O2 (g) → CO2 (g) + H2O (1)

D. CsHa (g) + 5O2 (g) → 3CO2 (g) + 4H2O (1)

C₃H₈ (g) + 5O₂ (g) → 3CO₂ (g) + 4H₂O (l)

(option D. with the proviso that the subscripts of propane's chemical formula must be corrected)

Explanation:

Propane is the saturated hydrocarbon, alkane, with chemical formula C₃H₈ or CH₃CH₂CH₃.

The complete combustion of the hydrocarbons yield carbon dioxide (CO₂) and water (H₂O).

The chemical equation that represents this combustion is:

C₃H₈ (g) + O₂ (g) → CO₂ (g) + H₂O (l) (skeleton equation: unbalanced)

Once you balance it, you get:

C₃H₈ (g) + 5O₂ (g) → 3CO₂ (g) + 4H₂O (l)

Left side Right side

C 3 3

H 8 4*2 = 8

O 5*2 = 10 3*2 + 4 = 10

That equation corresponds to the option D. of the list, with the proviso that the subscripts of propane's chemical formula must be corrected