Question

Combustion reactions are exothermic. The heat of reaction for the combustion of 2-methylheptane, C8H18, is 1.306×103 kcal/mol. What is the heat of combustion for 2-methylheptane in kcal/gram? 11.45 kcal/gram How much heat will be given off if molar quantities of 2-methylheptane react according to the following equation? 2 C8H18 + 25 O216 CO2 + 18 H2O

Answer 1

Answer:

11.45kcal/g

2.612 × 10³ kcal

Explanation:

When a compound burns (combustion) it produces carbon dioxide and water. The combustion of 2-methylheptane can be represented by the following balanced equation:

2 C₈H₁₈ + 25 O₂ ⇄ 16 CO₂ + 18 H₂O

It releases  1.306 × 10³ kcal every 1 mol of C₈H₁₈ that is burned.

What is the heat of combustion for 2-methylheptane in kcal/gram?

We know that the molar mass of C₈H₁₈ is 114.0g/mol. Then, using proportions:

$\frac{1.306 \times 10^{3}Kcal}{1mol} .\frac{1mol}{114.0g} =11.45kcal/g$

How much heat will be given off if molar quantities of 2-methylheptane react according to the following equation? 2 C₈H₁₈ + 25 O₂ ⇄ 16 CO₂ + 18 H₂O

In this equation we have 2 moles of C₈H₁₈. So,

$2mol \times\frac{1.306 \times 10^{3}kcal }{1mol} =2.612\times 10^{3}kcal$