Coefficients Party, Part 8

Chemistry Level 2

When liquid octane ( C X 8 H X 18 ) (\ce{C_8H_{18}}) combusts, it forms carbon dioxide and water vapor. The reaction can be modeled by the following, where α , \alpha, β , \beta, γ , \gamma, and δ \delta are positive coprime integers, α C X 8 H X 18 ( l ) + β O X 2 ( g ) γ C O X 2 ( g ) + δ H X 2 O ( g ) \alpha\ \ce{ C_8{H}_{18}}(l)+\beta\ \ce{ O_2}(g)\rightarrow \gamma \ \ce{ CO_2}(g)+\delta\ \ce{ H_2O}(g) Find α + β + γ + δ . \alpha+\beta+\gamma+\delta.


Image Credit: Wikimedia Jynto .


The answer is 61.

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4 solutions

Petru Lupsac
May 5, 2014

The balanced formula is: 2 C 8 H 18 + 25 O 2 > 16 C O 2 + 18 H 2 O 2C_{8}H_{18} + 25O_{2} -> 16CO_{2} + 18H_{2}O Thus we have: 2 + 25 + 16 + 18 = 61 2 + 25 + 16 + 18 = \boxed{61}

Milo Štěpán
May 22, 2014

By given rules we get series of equations: 8 α = γ 18 α = 2 δ 2 β = 2 γ + δ 8\alpha =\gamma \\ 18\alpha =2\delta \\ 2\beta =2\gamma +\delta

Considering it has infinite number of solutions (3 equations, 4 variables), we are looking for smallest integer solution. Solving for α , γ , δ \alpha ,\gamma ,\delta results in: α = 2 25 β γ = 16 25 β δ = 18 25 β \alpha =\frac { 2 }{ 25 } \beta \\ \gamma =\frac { 16 }{ 25 } \beta \\ \delta =\frac { 18 }{ 25 } \beta Therefore β = 25 \beta =25

Sukrut Waghmare
Jun 7, 2015

This question itself is wrongly framed as it not mentioned whether we have to take the smallest integer coefficients.

Thanks. I have updated the problem accordingly.

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Calvin Lin Staff - 5 years, 10 months ago
Aditya Gaur
Jun 25, 2014

see basically this was an easy according to this formula. if take as aC8H18+bO2-------------> cCo2 + dH2o now equate the same elements from lhs to rhs for ex. 8a=c here in lhs carbon has 8 atom and on RHS carbon has 1 atom so u can equate

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