Chemistry

• Entropy (Δ S) describes the dispersal of energy in a system.
• Enthalpy (Δ H) Describes the changes in energy.
• A spontaneous process occurs without any energy input.
• How do we know there are no energy changes?(Spontaneous)

  No bonds are made or broken.
• "Like dissolves like" truly means polar substances (or ionic) will dissolve in polar solvents. Non-polar substances will dissolve in non-polar solvents.
• When the solute and solvent have matching IMF they are more likely to mix.
• 
  

  $Δ H (solution)=$$ΔH(solute)+$$ΔH(solvent) +$$Δ(mixing)$
• In a hot pack (exothermic), bonds on the products are stronger.
• Exothermic dissolution process are driven by enthalpy because the bonds in the solution ΔH mixing are stronger than pure solute or solvent.
• In a icepack (Endothermic), bonds in the reactants are stronger.
• Endothermic dissolution process are driven by entropy because the bonnds in the ΔH mixing are weaker than the pure solute or solvent
• Endothermic is the energy of repulsions
• Exothermic is the energy of attractions
• A saturated solution is made when no additional solute will dissolve in the solution.
• When a saturated solution is in contact with undissolved solute, the dissolved and undissolved solutes are in dynamic equilibrium
• The solubility of a substance in a particular solvent is defined as the amount of substance required to make a saturated solution.
• $Solute +$$Solvent → Solution$


  This process is called dissolving.
• $Solution→Solute +$$Solvent$


  This process is called crystallizing.
• On a Solubility graph, the saturated line represents the maximum amount of solute that can be dissolved in a given amount of temperature.
• Anywhere below the saturated line, the solution is unsaturated.
• A solution is said to be supersaturated if more solute is dissolved than in a saturated solution.
• Supersaturated solutions are very unstable. A small disruption can force the solid to crash out of solution.
• Normally, heating a solution will increase the solubility.
• When a mixture is saturated, heating the solution will decrease the mass of the solid and increase the concentration of the solute in the surroundings.
• When a mixture is saturated, allowing some of the solution to evaporate will increase the size of the solid and not affect the concentration of the solute in the surroundings because there is no temperature change.
• When a mixture is saturated, removing some liquid from the top will not affect the mass of the solid and will not affect the concentration of solute in the surroundings.
• In a saturated solution, cooling the solution will increase the size of the solid and decrease the concentration of the solute in the solvent
• In a saturated solution, adding a small amount of regular water will decrease the size of the solid and not affect the concentration of the solute in the surroundings because there is no temperature change.
• In a saturated solution, adding a VERY large amount of water will decrease the size of the solid and decrease the concentration of the solute in the surroundings.
• In a saturated solution, changing the amount of water by a small amount will not change the concentration of solute in surroundings. Think of the solubility charts axis. It is amount of solute and temperature. If the solution is saturated then we need a lot of water to change the concetration.
• The two major factors affecting solubility in solutions are IMF and Temperature.
• Gases are less soluble in water at higher temperatures.
• Most Solids are more soluble at higher temperatures
• What part of Ethonol makes it soluble in water?

  The hydrogen bond.
• Pairs of liquids that mix in any proportion are said to be miscible.
• Pairs of liquids that do not mix significantly are said to immiscible.
• When two liquid's molecules share the similar IMF, strong attractions are produced when the substances mix making the two liquids miscible.
• At a higher temperature, there is higher Kinetic Energy in the gas particles.
• The reason why hot soda goes flat quicker than cold soda is because for the gas, as temperature increases, the solubility decreases and when gas can't dissolve anymore, it bubbles out.
• The solubility of liquids and solids in a solvent is doesn't change with pressure changes.