Question

Choose one of the following terms to match the definition or description given. a. alloy b. specific heat c. crystalline solid d. dipole-dipole attraction e. equilibrium vapor pressure f. intermolecular g. intramolecular h. ionic solids i. London dispersion forces j. molar heat of fusion k. molar heat of vaporization I. molecular solids m. normal boiling point n. semiconductor maximum pressure of vapor that builds up in a closed container

Short answer

The correct term that matches the definition "maximum pressure of vapor that builds up in a closed container" is e. Equilibrium vapor pressure.

Step-by-step solution

1. Understanding the terms

First, let's briefly understand each term from the list. a. Alloy: A mixture of two or more metals. b. Specific heat: The amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius. c. Crystalline solid: A solid material whose atoms are arranged in a highly ordered, repeating pattern extending in all three spatial dimensions. d. Dipole-dipole attraction: Attractive forces between two polar molecules. e. Equilibrium vapor pressure: The pressure exerted by a vapor when it is in equilibrium with its liquid or solid phase. f. Intermolecular: Forces between different molecules. g. Intramolecular: Forces within a single molecule. h. Ionic solids: Solids composed of oppositely charged ions. i. London dispersion forces: Weak attraction forces between nonpolar molecules. j. Molar heat of fusion: The energy required to melt one mole of a substance at its melting point. k. Molar heat of vaporization: The energy required to vaporize one mole of a substance at its boiling point. l. Molecular solids: Solids composed of individual molecules held together by intermolecular forces. m. Normal boiling point: The temperature at which a substance's vapor pressure equals the external pressure. n. Semiconductor: A material that has a conductivity between that of a conductor and an insulator.

2. Identifying the term that matches the definition

Out of the given terms, the one that matches the definition "maximum pressure of vapor that builds up in a closed container" is: e. Equilibrium vapor pressure: The pressure exerted by a vapor when it is in equilibrium with its liquid or solid phase. So, the correct answer is e. Equilibrium vapor pressure.

Key concepts

Intermolecular Forces

Intermolecular forces are the forces of attraction that act between molecules, differentiating them from intramolecular forces, which exist within a molecule. These forces significantly influence the physical properties of substances, such as boiling and melting points. They help explain why different substances hold together in solid and liquid forms.
You can think of intermolecular forces like the invisible glue holding separate molecules together. Without these forces, substances might struggle to maintain their solid or liquid state. There are several types of intermolecular forces:

• Dipole-dipole attractions: These occur between molecules with permanent dipoles, such as polar molecules. The positive end of one molecule is attracted to the negative end of another.
• Hydrogen bonds: A particularly strong type of dipole-dipole interaction, occurring when hydrogen is bonded to an electronegative atom like oxygen, nitrogen, or fluorine.
• London dispersion forces: These are weaker forces that arise from temporary, instantaneous dipoles in molecules, especially significant in nonpolar substances.

In understanding phase changes and vapor pressures, grasping these intermolecular forces is essential, as they determine how easily a substance can change from one phase to another.

Phase Changes

Phase changes are the transformations between different states of matter: solid, liquid, and gas. These changes happen due to variations in energy levels within a substance, affecting how molecules are organized.
During phase changes, the intermolecular forces play a crucial role in determining the amount of energy required. For example:

• Melting: Transition from solid to liquid. Requires energy to overcome the forces holding solid structures together (molar heat of fusion).
• Freezing: Transition from liquid to solid. Molecules lose energy and settle into a structured pattern.
• Boiling: When a liquid changes to a gas. Energy is needed to overcome the intermolecular forces, accounting for the molar heat of vaporization.
• Condensation: Transition from gas to liquid. Molecules cool down and come closer, forming intermolecular attractions again.

Each phase change involves a balance between energy input/output and intermolecular forces. Understanding this balance is key to mastering the concept of equilibrium vapor pressure in a closed system.

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid (or solid) form in a closed system. At this equilibrium, the rate of evaporation equals the rate of condensation. It's a crucial concept for understanding how liquids and gases behave in closed environments.
The equilibrium vapor pressure is influenced by temperature and the nature of the liquid. Higher temperatures increase vapor pressure since more molecules have enough energy to escape the liquid phase. Similarly, substances with weaker intermolecular forces tend to have higher vapor pressures, as less energy is required for molecules to vaporize.

• Normal boiling point: Occurs when the liquid's vapor pressure equals atmospheric pressure, causing a phase change from liquid to gas.
• Saturation: When the vapor pressure reaches a point where no more liquid can evaporate without an increase in temperature or decrease in volume.

Understanding vapor pressure helps explain phenomena like evaporation, condensation, and boiling. It's a key concept in predicting how substances will behave under various conditions.