Solution Chemistry Unit 10 Chapter 16

Vocabulary Solution: a homogenous mixture (substances are uniformly distributed and cannot be distinguished from one another) Solvent: the component of the solution present in the greatest quantity (usually H2O) Solute: the component present in quantity less than the solvent Solubility: ability of one substance to dissolve in another substance (H2O) e.g.: solubility of NaCl is 35 g/L

Types of Solutions TYPE EXAMPLE liquid / liquid water / alcohol liquid / solid NaCl / water liquid / gas CO2 / water gas / gas N2 / O2 / CO2 (air)

Solubility & Polarity Water is a good solvent because it is a polar substance H O H it is polar because electrons are held more closely by the oxygen (it is more electronegative than hydrogen) H O ( + ) ( + ) ( - ) H O H ( + ) ( + ) ( - ) and because the H2O is actually “V” shaped, one side of the molecule is slightly negative and the other side is slightly positive: it is polar

The most polar substances are ionic compounds e.g.: NaCl - the sodium is (+) - the chlorine is (-) Polar substances dissolve in other polar substances. Ionic example: NaCl dissolving H O H O ( + ) ( + ) ( - ) Cl- Na+ + H O H O H O Na+ Cl- H O H O H O Ionic compounds dissociate into “hydrated” ions

Polar covalent example: CH3OH dissolving ( + ) ( + ) ( - ) ( - ) ( + ) + H C O H O “polar interactions” or “hydrogen bonding”

Non-polar covalent example: CH4 does not dissolve in water. H C - this molecule is non-polar, therefore, water will not interact with it. This is why fats and oils don’t mix with water. Fats and oils are non-polar.