Chapter 3, Problem 46A

List four indicators that a chemical change has probably occured.

Interpretation Introduction

Interpretation:

In a chemical change, the four indicators that occurred needs to be explained.

Concept introduction:

The nature of any substance is explained by their chemical properties and physical properties. A chemical property describes how a substance reacts with other substances.

Answer to Problem 46A

There are four indicators of chemical change which are mentioned below:

1. Production of gas
2. Releasing energy or gain of energy
3. Color change
4. Formation of precipitation

Explanation of Solution

The main four indicators for a chemical change with an example are mentioned below:

1. Production of gas: In a chemical change, a new gas will be produced. For example, Sodium ignites when reacting with water. Sodium is metal, when this metal reacts with water, a new substance hydroxide is formed and hydrogen gas released.
2. Releasing of energy or gain of energy: In a chemical change, a substance will release or gain energy. For example, burning of wood, where the heat losses by the production of ash and gases.
3. Color change: In a chemical change, a substance will be changing its color. For example, changing in the color of leaves fall, this is a biochemical change where the composition of leaves is changing and completely destroyed.
4. Irreversible change: In a chemical change, reaction will be irreversible. For example, Iron rusting, when the iron reacts with moisture iron oxide will be formed which cannot be converted into iron.

Conclusion

In a chemical reaction these four indicators are helpful for identification of different compounds.