Question

Identify the correct coefificients to balance it
-C3H8+O2 to -CO2 +-H2O

Answer 1

`{\rm 1\; C_3H_8} + {\rm 5\; O_2} \to {3\; \rm CO_2} + {4\; \rm H_2O}`.

Step-by-step explanation:

`{\rm ?\; C_3H_8} + {\rm ?\; O_2} \to {?\; \rm CO_2} + {?\; \rm H_2O}`.

Among the four species in this reaction,
`\rm C_3H_8` is species with the largest number of atoms per molecule. Assume that the coefficient of this compound is
`1`.

`{\rm 1\; C_3H_8} + {\rm ?\; O_2} \to {?\; \rm CO_2} + {?\; \rm H_2O}`.

Number of atoms on the left-hand side of the reaction:

• 
  `\rm C`:
  `1 * 3 = 3`.
• 
  `\rm H`:
  `1 * 8 = 8`.
• 
  `\rm O`: not found yet.

By the conservation of atoms, the number of atoms on the right-hand side of the reaction should match those on the left-hand side. In this reaction,
`\rm CO_2` is the only product with carbon atoms, whereas
`\rm H_2O` is the only product with hydrogen atoms. These
`3` carbon atoms and
`8` hydrogen atoms would correspond to:

• 
  `3 / 1 = 3`
  `\rm CO_2` molecules, and
• 
  `8 / 2 = 4`
  `\rm H_2O` molecules.

`{\rm 1\; C_3H_8} + {\rm ?\; O_2} \to {3\; \rm CO_2} + {4\; \rm H_2O}`.

Number of atoms on the right-hand side of the reaction:

• 
  `\rm C`:
  `3 * 1 = 3`.
• 
  `\rm H`:
  `4 * 2 = 8`.
• 
  `\rm O`:
  `3 * 2 + 4 * 1 = 10`.

The number of
`\rm O` atoms on the left-hand side should match those on the right-hand side. In this reaction,
`\rm O_2` is the only reactant with
`\rm O\!` atoms. These
`10`
`\rm \! O` atoms would correspond to:

• 
  `5`
  `\rm O_2` molecules.

`{\rm 1\; C_3H_8} + {\rm 5\; O_2} \to {3\; \rm CO_2} + {4\; \rm H_2O}`.