Chapter 9, Problem 9.6P

Interpretation Introduction

(a)

Interpretation:

The standard heat of the formaldehyde formation from methanol and oxygen reaction given by the equation should be calculated.

$2{\text{CH}}_{\text{3}}\text{OH}\left(l\right)+{\text{O}}_{\text{2}}\to 2\text{HCHO}\left(g\right)+{\text{2H}}_{\text{2}}\text{O}\left(l\right):\Delta H_r^{°}=-326.\text{2 kJ}$

And standard heat of combustion of hydrogen is given by the equation:

${\text{H}}_{\text{2}}\left(g\right)+\frac{1}{2}{\text{O}}_{\text{2}}\to {\text{H}}_{\text{2}}\text{O}\left(l\right):\Delta {\hat{H}}_e^{°}=-285.\text{8 kJ}$

Concept introduction:

The standard heat of combustion is the number of calories or the total energy generated as heat when a certain compound goes through combustion in presence of oxygen under the standard conditions. Generally, a hydrocarbon reacts with oxygen in this type of reaction. This is also an exothermic reaction as it generates heat energy.

In Hess’s law, enthalpy change which involved in the chemical reactions are same, it doesn’t matter the steps involved in the reactions.

Interpretation Introduction

(b)

Interpretation:

The need of following the Hess’s Law to find the standards of reaction the given equation in sub part (a) should be explained.

Concept introduction:

The standard heat of combustion is the number of calories or the total energy generated as heat when a certain compound goes through combustion in presence of oxygen under the standard conditions. Generally, a hydrocarbon reacts with oxygen in this type of reaction. This is also an exothermic reaction as it generates heat energy.

In Hess’s law, enthalpy change which involved in the chemical reactions are same, it doesn’t matter the steps involved in the reactions. This reaction seems to be an endothermic reaction.