Propane gas (C3H8) combusts with oxygen gas (O2) to form water (H2O) and carbon dioxide (CO2). Write a balanced chemical equation for this reaction and explain the scientific principle (statement) that requires the balancing of an equation to make it conform to reality.

C3H8 + 5O2 → 4H2O + 3CO2.

Explanation:

let the balanced equation be A C3H8 + B O2 → C H2O + D CO2.

eqauting carbon hydrogen and oxygen on both sides

we get 3A = D, 8A = 2C, 2B = C + 2D

solving these three equations we get C = 4A and B = 5A

let A = 1

we get B = 5, C = 4, D=3

therefore the equation becomes

C3H8 + 5O2 → 4H2O + 3CO2.

mass must be conserved on both side of the equation so as to make the reaction possible as energy can neither be created nor be destroyed.