Solubility

The grams of solute that makes a saturated solution with 100 grams of a solvent is called its solubility. eg if 15 grams of sugar can dissolve in 100 grams of water at most then 15 grams is the solubility of sugar.

  Determination of Solubility
Take some amount (more than 100 grams)of a solvent. Start dissolving the test solute till no more of it dissolves. This means that we have reached a saturated solution. Now filter the solution to remove the undissolved solute. Weigh the filterate. Say it is 125 grams. Now boil out the solvent. Weigh again the solid solute left. Say it is 30 grams. From this we can calculate the weight of the solvent,
 125-30=95 grams. Now we can calculate the solubility of the test solute.

  95g of solvent dissolved 30g  of solute
  100g of solvent'll dissolve Xg of solute

    X=100×30÷95=31.6g

So the solubility of the given solute is 31.6 grams.

 Note: If the solute particles can be solvated by the solvent particles, the solute is said to be soluble in the given solvent. Solubility is achieved by ion-dipole or dipole -dipole interaction between solute and solvent or through the dielectric constant of the solvent. For example alcohols are soluble in water through H bonding a dipole dipole phenomenon and NaCl is soluble in water through ion dipole method.

 If the No. of solute particles exceeds than the solvent particles, then the solution is said to be saturated.

 Oils are insoluble in water because their particles can't be separated/solvated by water. We can force them temporarily but after awhile they mutually coagulate. There is no way for water molecules to trap them ie through its polarity or dielectric constant.
 Glucose, a monosaccaride is soluble in water by HB method where by water takes apart/solvate individual glucose molecules, C6H12O6 , and surrounds it through its molecules, H2O . Same is the case with oligosaccarides like sugar C12H22O11.
 But polysaccharides are unsoluble in water because there we don't have individual particles to be solvated and thus broken apart by water although the also have OH groups like the previous saccarides for HBonding with water. It is because they are actually strands of molecules called polymers. Although water does make HB but can't solvate/isolate individual particles, molecules. They are polymers like (C6H12O6)n.