(C) Bonding and Structure
After completing this topic you should be able to : (C) Bonding and Structure Solubility of ionic compounds, polar molecules and non-polar molecules. Ionic compounds and polar molecular compounds tend to be soluble in polar solvents such as water and insoluble in nonpolar solvents. Non-polar molecular substances tend to be soluble in non-polar solvents and insoluble in polar solvents. Solubility and bonding
Predicting solubility from solute and solvent polarities Learning intention Learn how the polarity of both the solute and solvent molecules influences solubility.
Solvent Action
Water is a polar molecule so it is a polar solvent. A liquid that a substance dissolves in is called a SOLVENT. Solvents can be either polar or non-polar molecules. Immiscible liquids do not mix, e.g. oil and water, however, non-polar liquids are miscible with each other. Polar solvents will usually dissolve polar molecules. Non-polar solvents will usually dissolve non-polar molecules. Water has a polar covalent bonding between O and H. O H H -- ++ ++ ++ ++ --
Dissolving in Water Hydrated ions Ionic Compound dissolving in water: -- ++ ++ -- ++ + -- ++ ++ -- ++ ++ -- ++ ++ ++ -- ++ ++ + -- ++ -- ++ ++
Dissolving in Water
Hydrated ions Pure Hydrogen chloride is polar covalent. When water is added it breaks to produce ions Cl - -- ++ ++ -- ++ ++ -- ++ ++ ++ -- ++ ++ H+H+ -- ++ -- ++ ++ H Cl ++ -- -- ++ ++ -- ++ ++
Dissolving in Water Generally, covalent molecules are insoluble in water. However, small molecules like ethanol (C 2 H 5 OH), with a polar O-H functional group, will dissolve, -- ++ ++ H2OH2O Ethanol ++ O H HH H H CC H --
Oil and water