Chapter 7, Problem 111AP

Interpretation Introduction

Interpretation: The balanced equations for the preparation of the given compounds are to be written and the physical state of the products and reactants in each equation is to be indicated.

Concept introduction:

In a balanced chemical equation, the number of atoms of each element on the reactant side is equal to the number ofatoms on the product side.

Elements that are present in the elementary state have zero oxidation state.

Answer to Problem 111AP

Solution:

a) $2{\text{KClO}}_{\text{3}}\left(s\right) \to 2\text{KCl}\left(s\right)+3{\text{O}}_{\text{2}}\left(g\right)$

b) ${\text{N}}_2\left(g\right)+3{\text{H}}_2\left(g\right) \to 2{\text{NH}}_3\left(g\right)$

c) ${\text{CaCO}}_{\text{3}}\left(s\right) \to \text{CaO}\left(s\right)+{\text{CO}}_{\text{2}}\left(g\right)$

d) $\text{Zn}\left(s\right)+{\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\left(aq\right) \to {\text{ZnSO}}_{\text{4}}\left(aq\right)+{\text{H}}_{\text{2}}\left(g\right)$

e) ${\text{CaCO}}_{\text{3}}\left(s\right) \to \text{CaO}\left(s\right)+{\text{CO}}_{\text{2}}\left(g\right)$

Explanation of Solution

a)Molecular oxygen

Molecular oxygen (${\text{O}}_2$) is atmospheric oxygen. The reaction is given as follows:

$\begin{array}{l}2{\text{KClO}}_{\text{3}}\left(s\right) \to 2\text{KCl}\left(s\right)+3{\text{O}}_{\text{2}}\left(g\right)\\ \text{Potassium Potassium Molecular }\\ \text{chlorate chloride oxygen}\end{array}$

b)Ammonia

The most common industrial method of preparing ammonia is through Haber’s process. The chemical equation for Haber’s process is given as follows:

$\begin{array}{l}{\text{ N}}_2\left(g\right)+3{\text{H}}_2\left(g\right) \to 2{\text{NH}}_3\left(g\right)\\ \text{Molecular Molecular Ammonia }\\ \text{nitrogen hydrogen }\end{array}$

On a commercial scale, it can also be prepared by using the saltammonium chloride. The reaction is as follows:

$\begin{array}{l}{\text{ NH}}_4\text{Cl}\left(g\right)+\text{ NaOH}\left(g\right) \to {\text{ NH}}_3\left(g\right)+\text{NaCl}(aq)+{\text{H}}_{\text{2}}\text{O}\\ \text{Ammonium Sodium Ammonia Sodium}\\ \text{chloride hydroxide chloride}\end{array}$

c) Carbon dioxide

Carbon dioxide is found abundantly in the atmosphere. For industrial purposes, it can be prepared by using calcium carbonate. The reaction is as follows:

${\text{CaCO}}_{\text{3}}\left(s\right) \to \text{CaO}\left(s\right)+{\text{CO}}_{\text{2}}\left(g\right)$

It can also be prepared by reacting calcium carbonate with hydrochloric acid as follows:

${\text{CaCO}}_{\text{3}}\left(s\right) +2\text{HCl}(aq)\to {\text{CaCl}}_2\left(aq\right)+{\text{CO}}_{\text{2}}\left(g\right)+{\text{H}}_{\text{2}}\text{O}\left(g\right)$

d)Molecular hydrogen

${\text{H}}_{\text{2}}$ gas is called the molecular hydrogen. It can be prepared by various methods but the most common method is the reaction of zinc metal with suphuric acid, which is as follows:

$\text{Zn}\left(s\right)+{\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\left(aq\right) \to {\text{ZnSO}}_{\text{4}}\left(aq\right)+{\text{H}}_{\text{2}}\left(g\right)$

e)Calcium oxide

Empirical formula of calcium oxide is $\text{CaO}$. It can be produced by the decomposition of ${\text{CaCO}}_{\text{3}}$ (same method as that of preparing ${\text{CO}}_{\text{2}}$).

The reaction is given as follows:

${\text{CaCO}}_{\text{3}}\left(s\right) \to \text{CaO}\left(s\right)+{\text{CO}}_{\text{2}}\left(g\right)$