What does each abbreviation, often used in chemical equations, represent? (a) \((g)\) (b) \((l)\) (c) \((s)\) (d) \((a q)\)

When encountering the abbreviation \(g\) in a chemical equation, one should immediately understand that it signifies a compound or an element in its gaseous state. In this condition, the particles (atoms, molecules, or ions) are widely separated and move freely, often at high speeds. They are not held together in any fixed position but collide with each other and the walls of their container.

For example, oxygen gas is represented as \(O_2 (g)\), indicating that it exists as discrete \(O_2\) molecules dispersed in the air. It's important to note the significant properties of gases: they expand to fill their container, have low density compared to liquids or solids, and are easily compressible.

Moving on to the abbreviation \(l\), it focuses on substances that are in a liquid state within a chemical equation. Liquids are characterized by an intermediate state of matter where they have a fixed volume but no fixed shape. They will take the shape of the container they are placed in. Here, the particles are closer together than in a gas and move around each other freely, which allows liquids to flow.

An example would be water at room temperature represented as \(H_2O (l)\). Unlike gases, liquids are not compressible to a significant extent and have a much higher density.

Regarding \(s\), this abbreviation denotes the solid state of a substance in chemical expressions. Solids are distinguished by their fixed shape and volume, due to the tightly packed arrangement of particles that only vibrate in place. This arrangement can be in a regular, repeating pattern, known as a crystal lattice, or amorphous without long-range order.

A common representation is table salt, which is shown as \(NaCl (s)\) in chemical equations. Solids are typically dense and are not readily compressible because the particles are already close together.

Lastly, the \(aq\) abbreviation is utilized to depict an aqueous solution. This state arises when a substance, such as a salt, sugar, or acid, is dissolved in water. The word 'aqueous' itself is derived from 'aqua', meaning water. In this type of solution, the solute particles are completely surrounded by water molecules.

As an illustration, when table salt dissolves in water, it is represented as \(NaCl (aq)\). This indicates that the \(Na^+\) and \(Cl^-\) ions are dispersed throughout the water.