Chapter 7, Problem 4QAP

Interpretation Introduction

Interpretation:

To determine when writing the chemical equation for a reaction, how do you indicate that a given reactant is dissolve in water and formed a precipitate.

Concept Introduction:

A balanced chemical equation is an equation that contains same number of atoms as well as of each element of reactants and products of reaction.

For example, the reaction between lead sulphide and oxygen is as follows:

$\begin{array}{l}2{\text{ PbS+3 O}}_2\to 2\text{PbO+}2{\text{SO}}_{\text{2}}\\ \text{ Reactants Products}\end{array}$

In the given reaction, the number of all atoms, on the both side are equal hence this is a balance reaction.

The most common driving forces which create product in chemical reactions are as follows:

1. Formation of a solid.
2. Formation of water.
3. Transfer of electrons.
4. Formation of gas.

If a substance is not soluble in water than it forms precipitate. The phase of the precipitate is solid. The precipitates are formed depending on the solubility of salt in water.