Question

What is the sum of the coefficients in the balanced equation for the complete combustion of

2-methylbutane?

• A. $12$
• B. $20$
• C. $16$
• D. $18$

Answer 1

Answer: (B)

$20$

There is a general reaction for the complete combustion of alkanes.

$C_n{H}_{2n+2}+\frac{3n+1}{2}{O}_2\to nC{O}_2+(n+1)H_{2}O$

Reaction for complete combustion of 2-methylbutane.

$C_5{H}_{12}+\frac{3\times 5+1}{2}{O}_2\to 5C{O}_2+6H_{2}O$

$C_5{H}_{12}+8O_2\to 5C{O}_2+6H_{2}O$

Therefore the sum of coefficients of the balanced equation is 1+8+5+6=20.