2.2
Solutions And
Solubility
Pg:45 -52
Solutions
A solution is made when a
solute is dissolved in a solvent.
More particles of the solute are
dissolved in a concentrated
solution than in a dilute
solution.
Solubility
Solubility
A solid that dissolves in a solvent such as water is said to be
soluble. Sodium chloride (common salt) and sugar are soluble.
A solid that will not dissolve in water is insoluble. Iron filings
are insoluble in water. If you keep adding a soluble solid to a
beaker of water, there comes a point where no more of the
solid will dissolve. You have made a saturated solution.
Some soluble substances are more soluble than others. If you
have 100 cm3 of water, you would be able to dissolve a lot of
sodium chloride in it, but only a tiny amount of lead chloride.
Sodium chloride has greater solubility than lead chloride.
Temperature and solubility
Most solutes will dissolve more quickly and easily in hot water
than in cold water. Think about what happens to the particles
when they have more energy. The more energy the particles
have, the more they vibrate and move.You can dissolve a greater
mass of the solute in hot water than in the same volume of cold
water. In other words, as the temperature increases, the
solubility of most solutes also increases.
– For example, if you have 100 g of water at 20°C you can
dissolve 204g of sugar in it. If you heat the water to 80 °C, you
can dissolve 362 g of sugar in it.
Other solvents
Water is not the only solvent. Some substances that are
insoluble in water will dissolve in other solvents.
For example, some types of oil paint are not soluble in water.
So if you need to clean your brushes after you’ve used oil
paint, you will need to use a solvent that the paint will
dissolve in, such as methanol ( methylated spirits).
Nail polish does not dissolve in water but dissolves in nail
polish remover.Most nail polish remover contains the solvent
propanone (acetone).