Chapter 9, Problem 9.8P

Interpretation Introduction

(a)

To determine:

The standard heat of formation of tetrachloroethane and standard heat of second reaction should be determined. The given equation is

$\begin{array}{l}{C}_2{H}_4(g)+2Cl\left(g\right)\to C_2{H}_{2}C{l}_4\left(l\right)+H_2\left(g\right):\\ C_2{H}_{2}C{l}_4\left(l\right)\to C_{2}HC{l}_3\left(l\right)+HCl\left(g\right)\end{array}$; $\Delta {\stackrel{}{H^{\circ }}}_r=-385.76kJ$ in words.

Concept introduction:

At room temperature and $1\text{atm}$ pressure, the heat required to absorb or evolve that leads to formation of one mole of compound from its constituent element is called as the heat of formation.

The term Enthalpy exchange is also used when formation of one mole of compound from its constituent elements occurs.

During any chemical reaction, when energy changes it is called as the state function according to Hess’s law. This state of function is defined as the energy changes in chemical reactions are same for any kind of reactions like one step reaction or several step reactions.

The total energy change can be calculated as summation of energy change occurring at every step.

Interpretation Introduction

(b)

To determine:

The standard heat of reaction for given reaction should be determined by use of Hess’s law. The given reaction is as follow:

$C_2{H}_4\left(g\right)+2C{l}_2\left(g\right)\to C_{2}HC{l}_3\left(l\right)+H_2\left(g\right)+HCl\left(g\right)$.

Concept introduction:

During any chemical reaction, when energy changes it is called as the state function according to Hess’s law. This state of function is defined as the energy changes in chemical reactions are same for any kind of reactions like one step reaction or several step reactions.

The total energy change can be calculated as summation of energy change occurring at every step.

Interpretation Introduction

(c)

To solve:

The heat is evolved or absorbed should be found for the given process.

Concept introduction:

At room temperature and

$1\text{atm}$ pressure, the heat required to absorb or evolve that leads to formation of one mole of compound from its constituent element is called as the heat of formation.

The term Enthalpy exchange is also used when formation of one mole of compound from its constituent elements occurs.

During any chemical reaction, when energy changes it is called as the state function according to Hess’s law. This state of function is defined as the energy changes in chemical reactions are same for any kind of reactions like one step reaction or several step reactions.

The total energy change can be calculated as summation of energy change occurring at every step.

Interpretation Introduction

(d)

To find:

The effect of temperature change from ${40}^{0}C$ to ${25}^{0}C$ should be determined for solution of part (c).

Concept introduction:

During any chemical reaction, when energy changes it is called as the state function according to Hess’s law. This state of function is defined as the energy changes in chemical reactions are same for any kind of reactions like one step reaction or several step reactions.

The total energy change can be calculated as summation of energy change occurring at every step.