solid

Examples of solid in the following topics:

• Amorphous Solids

  • Solids can be divided into two classes: crystalline and amorphous.
  • These solids are stabilized by the regular pattern of their atoms.
  • Most amorphous solids have some short-range order.
  • However, amorphous solids are common to all subsets of solids.
  • Most classes of solid can be found in an amorphous form.

• Solid to Gas Phase Transition

  • In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state.
  • The reverse process of sublimation is deposition (i.e., gas to solid).
  • For example, solid iodine, I2, is easily sublimed at temperatures around 100°C.
  • There are other solids whose vapor pressure overtakes that of the liquid before melting can occur.
  • Solid carbon dioxide (known as "dry ice") sublimes into the air.

• Molecular Crystals

  • Molecules held together by van der Waals forces form molecular solids.
  • This latter property often gives such solids a distinctive odor.
  • Whereas the characteristic melting point of metals and ionic solids is ~1000 °C, most molecular solids melt well below ~300 °C.
  • Molecular solids also have relatively low density and hardness.
  • Conductivity of molecular solids can be induced by "doping" fullerenes (e.g., C60).

• Alloys

  • An alloy is a mixture or metallic solid solution composed of two or more elements.
  • An alloy is a mixture or metallic-solid solution composed of two or more elements.
  • Complete solid solution alloys give single solid phase microstructure.
  • Complete solid solution alloys give single solid phase microstructure.
  • Unlike pure metals, most alloys do not have a single melting point; rather, they have a melting range in which the substance is a mixture of solid and liquid.

• Liquid to Solid Phase Transition

  • Most liquids freeze by crystallization, the formation of a crystalline solid from the uniform liquid.
  • In the presence of irregularities on the surface of the containing vessel, solid or gaseous impurities, pre-formed solid crystals, or other nucleators, heterogeneous nucleation may occur.
  • Matter exists as solids, liquids and gases, and can change state between these.
  • On the right side of the barrier is a solid material (large atoms).
  • How quickly do the more energetic atoms melt the solid?

• Three States of Matter

  • A solid's particles are packed closely together.
  • As a result, a solid has a stable, definite shape and a definite volume.
  • Solids can only change shape under force, as when broken or cut.
  • A solid can transform into a liquid through melting, and a liquid can transform into a solid through freezing.
  • It can also exist in equilibrium with a liquid (or solid), in which case the gas pressure equals the vapor pressure of the liquid (or solid).

• Major Features of a Phase Diagram

  • Along the dotted green phase boundary, we see the anomalous behavior of water: it exists as a solid at low-enough temperatures and high-enough pressures.
  • At the triple point, water in the solid, liquid, and gaseous states coexist.
  • In this phase diagram, which is typical of most substances, the solid lines represent the phase boundaries.
  • The green line marks the freezing point (or transition from liquid to solid), the blue line marks the boiling point (or transition from liquid to gas), and the red line shows the conditions under which a solid can be converted directly to a gas (and vice-versa).
  • The dotted green line is meant to replace the solid green line in the corresponding phase diagram of water.

• Heterogeneous and Multiple Equilibria

  • For example, equilibrium could exist between solid and gaseous species, between liquid and aqueous species, etc.
  • C(s) is omitted from the expression because it exists in the solid phase.
  • The reason for this is because the concentration of a pure solid or a pure liquid is always the same; its "concentration" is really its density, which is uniform regardless of sample size.
  • As a result, the activity, or ideal concentration, of a liquid or a solid is defined as 1.
  • Since their activity is unity, and anything multiplied by 1 remains itself, solids and liquids have no effect whatsoever on the equilibrium expression.

• Interpreting Phase Diagrams

  • Phase diagrams are divided into three single phase regions that cover the pressure-temperature space over which the matter being evaluated exists: liquid, gaseous, and solid states.
  • When evaluating the phase diagram, it is worth noting that the solid-liquid phase boundary in the phase diagram of most substances has a positive slope.
  • This is due to the solid phase having a higher density than the liquid, so that increasing the pressure increases the melting temperature.
  • However, the solid-liquid phase boundary for water is anomalous, in that it has a negative slope.
  • The dotted green line refers to the solid-liquid phase boundary for water.

• Factors that Affect Reaction Rate

  • In a reaction between a solid and a liquid, the surface area of the solid will ultimately impact how fast the reaction occurs.
  • This is because the liquid and the solid can bump into each other only at the liquid-solid interface, which is on the surface of the solid.
  • The solid molecules trapped within the body of the solid cannot react.
  • Therefore, increasing the surface area of the solid will expose more solid molecules to the liquid, which allows for a faster reaction.
  • Keep in mind this logic only works for gases, which are highly compressible; changing the pressure for a reaction that involves only solids or liquids has no effect on the reaction rate.