An inorganic chemist synthesizes an unknown cobalt chloride hydrate
CHEMISTRY · Multi-part · CBSE · Chemistry · Acids, Bases and Salts · Acids, Bases and Salts
Problem
An inorganic chemist synthesizes an unknown cobalt chloride hydrate. The bright-purple crystals are analyzed as follows:
• Mass of empty crucible: 21.432 g
• Mass of crucible + hydrated crystals: 23.876 g
• After gentle heating to constant mass, mass of crucible + anhydrous residue: 23.012 g
Assume that all mass loss is due to removal of water and that no decomposition of the anhydrous salt occurs.
(a) Determine the empirical formula of the hydrate.
(b) A student claims that the compound could also be CoCl₂·8H₂O within the experimental uncertainty of ±0.003 g for each mass measurement. Show quantitatively whether this claim is justified.
(c) Using your result from part (a), calculate the percent by mass of cobalt in the hydrated crystals.