Solids and Liquids - High School Chemistry

Freezing point depression refers to the phenomenon that occurs when the freezing point of a solution is decreased due to the presence of ions or molecules. The freezing point depression is given by the formula:

refers to the van't Hoff factor, which is the number of ions created by dissolving a single molecule of the solute. In this case, the van't Hoff factor is two because HCl will create two ions per molecule in solution.

referes to the molality, which is the moles of solute per kilogram of solvent. We can rewrite our equation in these terms:

We know all of these terms, allowing us to solve:

This tells us that the freezing point of the solution is 11.16 degrees less than the freezing point of pure water.

Adding salt to water raises its boiling point. This allows the water to get hotter before evaporating. Boiling point elevation is a colligative property. Thus the increase in boiling point is proportional to the number of dissolved particles in solution, not the type of dissolved particles.

By definition, viscosity is the measure of a liquid's resistance to flow. If a liquid has a high resistance to flow, it has a high viscosity. It may not necessarily have a high boiling point or melting point, nor be easily soluble in other liquids.

Vapor pressure relates to the molecules' ability to escape from their liquid form into a gaseous state. The weaker the intermolecular forces, the greater the vapor pressure (VP). Liquids with hydrogen bonding general have high VP. Bigger and longer molecules have larger VP then smaller ones. Methane does not hydrogen bond, and it is a relatively small molecule, thus many molecules will have enough energy to break the weak intermolecular forces and enter the gaseous phase. Both water and methanol can hydrogen bond. Propane has weak bonds like methane, but it is a larger molecule and will thus have a lower vapor pressure.

A solid is defined as having a definite shape and definite volume. A liquid is defined as having a definite volume, but not a definite shape. A gas is defined as neither having a definite shape nor a definite volume.

Solids are defined as having definite shapes and volumes. The atoms in a solid touch one another and are fixed in rigid positions. Unlike liquids or gases, molecules inside a solid are not able to freely move past one another. Solids will retain their shape even when put in open atmospheres.

Aluminum is not a high-density metal. You may figure this out by comparing aluminum's density (2.7 g/mL) to the density of other metals. Aluminum is very lightweight compared to other metals, making it ideal for the construction of things like airplanes.

Aluminum is a good conductor of heat and electricity. It is ductile, meaning it can be turned into wire, and it is malleable, meaning it can be made into sheets.

Solids have well defined shapes because their atoms are held tightly together, only allowing localized movement. Because a solid's atoms are so close together, solids are incompressible. There so little space between atoms that they can't get any closer together. The reason a solid's atoms are so close together is they experience strong intermolecular forces, resulting in high stability. Solids can either be crystalline or amorphous in structure. Crystalline structure is regimented and grid-like, while amorphous has no regular, repeating pattern of atoms.

A crystalline solid is made up of a repeating pattern of atoms called a crystal lattice. Atoms moving about randomly, and taking the shape of their container are descriptions of fluids (liquids and gasses).

Dissolving a solute in a solvent increases the number of dissolved particles per mass of solvent. Freezing point depression is a colligative property of solutions, and will decrease as the molality of the solution increases. Boiling point and osmotic pressure increase as the molality of the solution increases. Temperature is unaffected by the dissolution of solutes in a solvent.

The salt decreases the freezing point of the water. Upon addition of salt to icy roads and sidewalks, the ice melts, making it safer to drive and walk. Freezing point depression is a colligative property and depends on the number of dissolved particles, not the type of particles. Thus, sugar would also decrease the freezing point of ice. The amount the freezing point decreases is proportional to the number of dissolved solutes in the solution.

Crystals, or crystalline solids consist of repeated, regular pattern of atoms known as a crystal lattice. Amorphous solids do not have a lattice, and consist of a mass of atoms without a repeated pattern.