Solubility of solids in liquids

What does it mean if something dissolves?

•The dissolving process involves the sugar molecules being pulled away from each other.

•When the sugar molecules are pulled apart (dissolved) they remain as sugar molecules and do not break down into the elements that make up sugar

(C, H, O)

Solubility and Rate of Dissolution

•Solid drug must pass into solution to be absorbed

•

•Rate of dissolution may influence therapeutic response and blood levels

•Decreasing particle size and increasing surface area will increase rate of dissolution at a given temperature

Factors Affecting Solubility

1. Nature of Solute / Solvent. - Like dissolves like

2. Temperature

  i) Solids/Liquids - Solubility increases with Temperature

  Increase in Tem.  increases motion and collision between solute / solvent.

  ii) gas - Solubility decreases with Temperature

  Increase in Tem.  result in gas escaping to atmosphere.

3. Pressure Factor

  i) Solids/Liquids - Very little effect

  Solids and Liquids are already close together, extra pressure will not   increase solubility.

  ii) gas - Solubility increases with Pressure.

  Increase pressure squeezes gas solute into solvent.

•Solids, liquids dissolving in a solvent:

–Solubility often increases

  with temperature,

  but not always

–Hard to predict