Question

Gasoline is composed primarily of hydrocarbons, including manywith eight carbon atoms, called octanes. One of the cleanestburning octanes is a compound called 2,3,4-trimethylpentane, whichhas the following structural formula.

CH₃ CH₃ CH₃
H₃C CH CH CH CH₃
The complete combustion of 1 mol of this compound to CO₂(g) and H₂O(g) leads to ΔHdegree =-5064.9 kJ//mol.
(a) Write a balanced equation for the combustion of 1 mol of C₈H₁₈ (l). (Use the lowest possiblecoefficients. Use fractional coefficients where needed. Include states-of-matter under the given conditions in youranswer.)

Answer 1

The balanced equation for the combustion of 2,3,4-trimethylpentane (C8H18) is C8H18(l) + 25/2 O2(g) → 8 CO2(g) + 9 H2O(g).

Step-by-step explanation:

The combustion of hydrocarbons involves reacting the hydrocarbon with oxygen to produce carbon dioxide and water. In the case of the hydrocarbon 2,3,4-trimethylpentane (C8H18), an octane, the balanced chemical equation for its complete combustion is:

C8H18(l) + 25/2 O2(g) → 8 CO2(g) + 9 H2O(g)

To balance the equation, we need to ensure that the number of atoms of each element is the same on both sides. For carbon, there are 8 carbon atoms in 2,3,4-trimethylpentane, so we need 8 molecules of CO2. For hydrogen, there are 18 hydrogen atoms, which results in 9 molecules of H2O. For oxygen, we have 8 × 2 = 16 atoms from CO2 and 9 × 1 = 9 atoms from H2O, giving a total of 25 oxygen atoms required from O2, which is 25/2 molecules of O2.