Description
When we balance chemical equations, we sometimes end up with a coefficient that’s a decimal.
For example, in the combustion of ethane (C₂H₆), you might write:
C₂H₆ + 3.5O₂ → 2CO₂ + 3H₂O.
That 3.5 can look strange — how can you have half a molecule of oxygen?
But those coefficients aren’t literal counts of molecules; they show ratios.
Using a decimal is just one way to express the correct ratio between reactants and products.
If you prefer whole numbers, you can multiply everything by 2 and get:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O.
Both versions describe the same chemical relationship and both are correctly balanced.
The choice to use a decimal or a whole number just depends on what’s most convenient for the problem you’re solving OR what your teacher prefers!