Calcium, Ca2+
Most common oxidation state: +2
M.P. 845o
B.P. 1420o
Density 1.55 g/cm3
Characteristics: Rather soft, very active metal. Very similar to barium in its chemical properties.
Characteristic reactions of Ca2+:
Sulfate Ion:
Soluble sulfates, such as sulfuric acid, do not precipitate Ca2+ as calcium sulfate, unless the calcium ion is present in very high concentrations.
Sodium Hydroxide:
Calcium hydroxide can be precipitated by addition of sodium hydroxide if Ca2+ is present in moderate concentration (>~0.02 M).
Ammonium Carbonate:
This forms a precipitate similar to that formed with Ba2+.
Sodium Oxalate:
The behavior is similar to that of Ba2+, but the precipitate is much less soluble in water and is insoluble in acetic acid. CaC2O4.H2O is soluble in mineral acids.
Flame Test:
Solutions of calcium salts give a yellow-red color to a Bunsen burner flame, sometimes with a sparkly appearance.
No Reaction:
Cl-, NH3(aq)