Chapter 2, Problem 69A

Interpretation Introduction

Interpretation: The classification of a substance as solid, liquid, or gas needs to be explained.

Concept Introduction: There are generally three states of matter that is solid, liquid and gas. Substances that are solid at room temperature have high melting and boiling points. Melting point is defined as the temperature at which a solid substance starts melting. The boiling point is defined as the temperature of a liquid when its vapor pressure is equal to the atmospheric pressure. This is the temperature when liquid starts boiling and converts into vapor.

Explanation of Solution

Any matter can be changed from its state to another state by physical methods. For example, ice is solid but on mild heating, it can be converted into liquid (water). Thus, a change in state from solid to liquid takes place. On further heating liquid (water) state can change to a gaseous state (vapor). In all three states, the composition of water remains the same that is ${\text{H}}_{\text{2}}\text{O}$ .

All substances must have a natural state. This is the state in which they are present naturally or at room temperature. Here, heating and cooling change the state of matter, but the natural state of any matter is considered its actual state. For example, the natural state of water is liquid because it is liquid at room temperature. The state of any matter depends on its melting and boiling point. Substances with a very low melting point, generally have liquid states. On the other hand, substances with a very low boiling point, generally have a gaseous state. The natural state of the substance is its state when the temperature is between its melting and boiling point.