Solutions

• Homogenous mixtures can be divided into two types: colloid & solution
• a homogenous mixture is made up of atoms, molecules, or ions
• components of solutions: solute & solvent
• solute - dissolved medium
• solvent - dissolving medium
• aside from water, the substance with the higher quantity is the solvent
• solubility - the amount of solute that can be dissolved in a given amount of solvent at room temperature under given conditions
• 3 types of solutions according to phase: solid, liquid, gas
• 3 types of solutions according to their concentration: unsaturated, saturated, supersaturated
• An unsaturated solution contains less solute than the solution is capable of dissolving.
• A saturated solution contains the maximum amount of solute that is capable of dissolving.
• A supersaturated solution contains more solute than can be dissolved.
• A supersaturated solution is unstable and crystals may form
• types of reactions occurring in solutions: exothermic reactions & endothermic reactions
• exothermic reactions release energy from the system in the form of heat
• exothermic reactions are warm to touch
• endothermic reactions absorbs energy into the system from its surroundings in the form of heat
• endothermic reactions are cool to touch
• factors affecting solubility:

  1. nature of the solute and the solvent
  2. effect of temperature
  3. effect of pressure
  4. surface area
  5. stirring
• rule of thumb: "like dissolves like"
• ionic solute + polar solvent -> soluble/miscible
• miscible - fluids that can combine
• water + oil -> immiscible
• solubility of gas in liquid increases with a decrease in temperature, and decreases with an increase in temperature
• in general, the solubility of solids increases with an increase in temperature for endothermic reactions (A + B + heat -> AB)
• in general, the solubility of solids decreases with an increase in temperature for exothermic reactions (A + B -> AB + heat)
• when pressure is increased, the molecules or ions come closer to each other and there are more chances for interaction between the solute and the solvent
• solubility of gas in liquids increases with an increase in pressure
• in diving, when the pressure underwater is too high, the inhaled nitrogen in your body could get dissolved into your blood. if you emerge too quickly, your blood depressurizes inside your body, thus affecting circulation.
• the greater the surface area, the greater the interaction of the solute and solvent, thus increasing solubility
• a big cube that is 1m^3 has less surface area than 3 small cubes amounting to the same volume
• stirring disperses the solute particles into other sections of the solvent, which increases the dissolution process
• colligative properties - properties that depend solely on the number of particles of solute present but not on the kind and nature of the solute
• colligative properties of solutions:

  1. vapor pressure reduction
  2. boiling point elevation
  3. freezing point depression
  4. osmotic pressure
• volatile - molecules escape
• examples of volatile substances: mothballs, LPG
• vapor pressure reduction - the non-volatile solute molecules take up space at the surface, thus preventing the escape of the solvent molecules
• in vapor pressure reduction, the interaction between the solute and the solvent is greater than the solvent-solvent interaction
• the greater the concentration of solute particles, the greater the vapor pressure reduction
• greater vapor pressure reduction = less vapor pressure