6.8 Types of solids
Ionic Solids properties
ionic solids have high mpt and bpt,
do not conduct electricity when solid, conduct electricity when molten or aqueous.
Ionic solids form clear crystals making a lattice
Write dissociation reactions of ionic compounds in water. The equations must be balanced for atoms and for charge
Precipitate: is solid formed when mixing two aqueous solutions.
Precipitation reaction: is a reaction where a precipitate (solid) is formed.
Demonstration: Different precipitation reactions:
e.g i) silver nitrate and sodium chloride
ii) silver nitrate and sodium bromide
iii) silver nitrate and sodium iodide
iv) lead(II) nitrate and sodium sulphate
v) calcium chloride and sodium carbonate
Determine [ions] present given number of moles of salt and volume of solution.
Write a complete formula equation, a complete ionic equation, a net-ionic equation to represent a precipitation reaction
Predominant ions: is that take part in the reaction
Spectator ions: ions that do not take part in a reaction
Determine the concentration of each ion present in a solution prepared by mixing two other solutions without precipitate formation
Determine the concentration of each ion present in a solution prepared by mixing two other solutions resulting in the formation of a precipitate
Molecular Solids properties
Molecular solids are made up of molecules. Examples of molecular solids are wax, sugar, hydrogen chloride, ammonia ...
low mpt and bpt
In general they remain molecular when dissolved in water and are non-electrolyte
In general they are non-electrolytes: sugar (s)→ sugar (aq)
Some molecular compounds like acids e.g hydrogen chloride are electrolytes:
HCl(g)→H+(aq) + Cl- (aq)
Other types of solids: metallic solids and network solids
Metallic solids: e.g Cu, Ag, Na
Network solids / giant molecular/ giant covalent solids are atomic solids made up of atoms joined together by strong covalent bonds. Network solids are characterized by their high melting point and boiling point. e.g Sand (SiO2) , graphite (C) and diamond(C)