MEASUREMENTS AND CALCULATIONS IN CHEMISTRY - HYDRATES

Dr. Chin Chu

Chemistry

River Dell High School

DEFINITION:Hydrates in Inorganic Chemistry – are inorganic salts “containing water molecules combined in a definite ratio as an integral part of the salt crystal that are either bound to a metal center or that have crystallized with the metal complex.

NAMING OF HYDRATES

NAMING OF HYDRATES – EXERCISE

Formula Name

CoBr2·6H2O

ZnSO4·7H2O

Copper(II) nitrate monohydrate

Iron(III) nitrate nonahydrate

NAMING OF HYDRATES – EXERCISE ANSWERS

Formula Name

CoBr2·6H2O Cobalt(II) bromide hexahydrate

Cu(NO3)2·H2O

ZnSO4·7H2O

Fe(NO3)3·9H2O

Copper(II) nitrate monohydrate

Zinc sulfate heptahydrate

Iron(III) nitrate nonahydrate

HOW TO FIGURE OUT THE HYDRATE FORMULA?

THE PROCESS

HYDRATES EXAMPLEA calcium chloride hydrate has a mass of 4.72 g. After heating for several minutes the mass of the anhydrate is found to be 3.56 g. Use this information to determine the formula for the hydrate.

A hydrate of magnesium sulfate has a mass of 13.52 g. This sample is heated until no water remains. The MgSO4 anhydrate has a mass of 6.60 g. Find the formula and name of the hydrate.

When 8.00 g of Pb(C2H3O2)2· xH2O are heated, 1.14 g of H2O are driven off. Find the chemical formula and the name of the hydrate.

A hydrate is determined to be 45.43% water and 54.57% CoCl2. Find the chemical formula and name for this hydrate. (*Hint – assume that there is 100 g total of hydrate compound.)

HYDRATES – PRACTICE PROBLEMS

[MgSO4·7H2O, magnesium heptahydrate]

[Pb(C2H3O2)2· 3H2O, lead(II) acetate trihydrate]

[CoCl2· 6H2O, cobalt(II) chloride hexahydrate]

HYDRATES – PRACTICE PROBLEMS ANSWERS