A student determines the formula of a hydrate of CuSO4 (M=159.6 g/mol). Mass of empty crucible = 25.124 g. Crucible + hydrate = 27.624 g. The crucible is heated strongly until the blue color turns white, then cooled in a desiccator and reweighed: 26.724 g. Heating is repeated until constant mass is reached.
What is the formula of the hydrate?
- A
CuSO4 . 2 H2O
- B
CuSO4 . 7 H2O
- Ccheck_circle
CuSO4 . 5 H2O
- D
CuSO4 . H2O
Explanation
mass anhydrous CuSO4 = 1.600 g; mol = 0.01003. mass H2O lost = 0.900 g; mol = 0.04994. ratio = 4.98 ~ 5 -> CuSO4 . 5 H2O.