Question

Indicate the physical state (solid, liquid, or gas) for gallium given its melting point \(\left(30^{\circ} \mathrm{C}\right)\) and boiling point \(\left(2403^{\circ} \mathrm{C}\right)\) under the following conditions: (a) Ga in ice water (b) Ga in boiling water

Short answer

(a) Solid at 0°C; (b) Liquid at 100°C.

Step-by-step solution

Understanding the Melting and Boiling Points

Gallium has a melting point of \(30^{\circ} \text{C}\) and a boiling point of \(2403^{\circ} \text{C}\). This means at temperatures below \(30^{\circ} \text{C}\), gallium is solid, between \(30^{\circ} \text{C}\) and \(2403^{\circ} \text{C}\), it's a liquid, and above \(2403^{\circ} \text{C}\), it is a gas.

Evaluating Gallium in Ice Water

Ice water is typically at \(0^{\circ} \text{C}\). Since \(0^{\circ} \text{C}\) is below gallium's melting point of \(30^{\circ} \text{C}\), gallium in ice water will be in the solid state.

Evaluating Gallium in Boiling Water

Boiling water is at \(100^{\circ} \text{C}\). Since \(100^{\circ} \text{C}\) is between gallium's melting point of \(30^{\circ} \text{C}\) and its boiling point of \(2403^{\circ} \text{C}\), gallium in boiling water will be in the liquid state.

Key concepts

Melting Point

The melting point of a substance is a crucial phase transition temperature where a solid turns into a liquid. For gallium, this happens at \(30^{\circ} \text{C}\). This means that below this temperature, gallium remains in its solid form.
At the melting point, the kinetic energy of the molecules is just enough to break free from their rigid positions in the solid structure. As a solid heats up and reaches its melting point, it absorbs energy known as heat of fusion. This heat increases the vibrations of its particles until they move past each other, converting the substance into a liquid.

• Ice Water Example: In an environment like ice water, which is at \(0^{\circ} \text{C}\), gallium remains a solid because the temperature is below its melting point.
• Everyday Life: Understanding melting points is important in everyday applications, like predicting the behavior of materials in different climates and conditions.

Boiling Point

The boiling point is another critical phase transition, where a liquid becomes a gas. Gallium boils at a staggering \(2403^{\circ} \text{C}\), which is much higher than everyday temperatures. This high boiling point indicates that gallium will remain a liquid over a wide range of temperatures under normal conditions.
When a liquid reaches its boiling point, the particles have enough energy to overcome atmospheric pressure and transition into a gas. This process requires significant energy known as the heat of vaporization. Essentially, this energy disrupts the intermolecular forces binding the liquid particles together.

• Boiling Water Example: In boiling water at \(100^{\circ} \text{C}\), gallium is far below its boiling point, so it stays in liquid form.
• Applications: Knowing boiling points helps in industrial processes like distillation and informs culinary heat applications.

States of Matter

Matter primarily exists in three states: solid, liquid, and gas. The state of matter of a substance depends on its temperature relative to its melting and boiling points.

• Solid State: In the solid state, molecules are tightly packed in a fixed structure, allowing limited movement. This is the case with gallium below \(30^{\circ} \text{C}\), such as when cooled in ice water.
• Liquid State: When molecules have more energy and fluid movement, the substance is a liquid, as with gallium between \(30^{\circ} \text{C}\) and \(2403^{\circ} \text{C}\), such as in boiling water.
• Gas State: With maximum energy, molecules spread far apart, making the gas state. Gallium reaches this state above \(2403^{\circ} \text{C}\), which is rare in normal environments.

Understanding these states and their transitions is vital in fields ranging from chemistry to materials science, as they define how substances behave under different thermal conditions. This knowledge aids in predicting and manipulating the properties for practical uses.