Salts and ionic equations Flashcards
what is a salt?
a salt is a substance formed when a metallic ion or an ammonium ion replaces one or more hydrogen ions of an acid
ionic compound consisting of a cation other than H and an anion other than OH or O
what substances are soluble (memorise)
all group 1 and ammonium salts
all nitrates (NO3)
all sulfates except PbSO4 and BaSO4 (CaSO4 and AgSO4 are only sparingly soluble)
all chlorides, bromides and iodides except silver (II) and lead(II) chloride, bromide, or iodide
group 1 and ammonium carbonates (NH4)
group 1 oxides (O)
group 1 hydroxides (OH)
what substances are insoluble?
PbSO4, BaSO4
silver and lead (II) chloride, bromide, iodide
all carbonates are insoluble except group 1 and ammonium carbonates
all metal oxides are insoluble except group 1 oxides
all hydroxides are insoluble except group 1 hydroxides
what technique must we use to attain an insoluble salt?
precipitation
what is precipitation?
A reaction involving mixing 2 aqueous solutions to form an insoluble solid that separates out from the reaction mixture. The insoluble solid is the precipitate.
procedure of precipitation
- 2 solutions are selected. One of the reagents contributes the cation and another contributes the anion.
- Mix the 2 solutions. one of the reagants will be added in excess and would be left as an unreacted reagant
- The insoluble salt is formed as a precipitate and can then be separated from the aqueous solution by filtration.
- The salt is washed with distilled water and wiped dry with filter paper to remove contaminant chemicals that are on the surface of the crystals.
example of procedure of precipitation
reagent 1 : Silver nitrate
reagent 2: Sodium chloride
Chemical equation: AgNO3 + NaCl –> AgCl + NaNO3
procedure: 1. Mix silver nitrate solution and sodium chloride solution together.
2. Filter the mixture and collect the residue. The residue is silver chloride.
3. Wash the salt with water.
4. Dry the silver chloride residue between pieces of filter paper.
