Question

Balance ${{C}_{8}}{{H}_{18}}+{{O}_{2}}\to C{{O}_{2}}+{{H}_{2}}O?$

Answer 1

Octane is a hydrocarbon and an alkane with the chemical formula ${{C}_{8}}{{H}_{18}}$ and the structural formula $C{{H}_{3}}{{(C{{H}_{2}})}_{6}}C{{H}_{3}}$ in its condensed form. The quantity and position of branching in the carbon chain varies across structural isomers of octane. 2,2,4-trimethylpentane (also known as iso-octane) is one of these isomers and is used as one of the standard values in the octane rating scale. Octane is a gasoline component (petrol). Octane, like all low-molecular-weight hydrocarbons, is highly flammable and volatile.

Complete answer:
A combustible substance is one that can burn (combust) in the presence of air. Combustible materials that ignite quickly at room temperature are known as flammable materials. In other words, a combustible substance takes some effort to ignite, but a flammable material ignites instantly when exposed to flame. The degree of flammability or combustibility in air is primarily determined by the material's volatility, which is linked to its composition-specific vapour pressure, which varies with temperature.
Octane on combustion gives carbon dioxide and water.
${{C}_{8}}{{H}_{18}}+{{O}_{2}}\to C{{O}_{2}}+{{H}_{2}}O$
Now let us balance the atoms
Any hydrocarbon that is completely burned produces carbon dioxide and water. To begin, add up all of the atoms. Based on the subscripts, you have
Left side: C = 8
H = 18
O = 2
Right side
C = 1
H = 2
O = 2 + 1 on the right side (do not add this up yet)
Second, choose the atom that is the simplest to balance. The C atom in this situation. Always keep in mind that while balancing, you are NOT SUPPOSED TO CHANGE THE SUBSCRIPTS; instead, you are only supposed to place coefficients before the substance (as changing the subscripts means that you are changing the molecular structure instead).
left side: C = 8 H = 18 O = 2 right side: C = (1 x 8) = 8 H = 2 O = (2 x 8) + 1
Because $C{{O}_{2}}$ is a substance, the coefficient must be applied to both the C and the two O atoms, as they are all linked together.
Third, find the atom that is the simplest to balance.
${{C}_{8}}{{H}_{18}}+{{O}_{2}}\to 8C{{O}_{2}}+9{{H}_{2}}O$
C = 8 H = 18 O = 2 on the left; C = 8 H = 18 O = 2 on the right.
C = (1 x 8) = 8
H = (2 x 9) = 18
O = (2 x 8) + (1 x 9) = 25
All that's left to do now is balance the O atoms. We can use our fractions knowledge to balance the left side of the equation since the total of O atoms on the right side is an odd number.
Thus
${{C}_{8}}{{H}_{18}}+\dfrac{25}{2}{{O}_{2}}\to 8C{{O}_{2}}+9{{H}_{2}}O$ is the balanced equation.

Note:
On the reactant and product sides of a balanced chemical equation, there are equal quantities of atoms for each element involved in the reaction. This is a condition that the equation must meet in order to be compatible with the conservation of matter rule. It may be verified by adding the numbers of atoms on both sides of the arrow and comparing them to check that they are equal. Note that the number of atoms in any formula involving that element is computed by multiplying the coefficient by the element's subscript in the expression.