Octane (C8H18) is a liquid that 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.

Answer 1

How about
2 C8H18 + 25 O2 ---> 18 H2O + 16 CO2

C 16 left 16 right
H 36 left 36 right
O 50 left 18 + 32 = 50 right

Conservation of mass means there must be the same atoms of each element left and right. In a chemical (not nuclear) reaction one element does not change into another.