Multiply the GMW, expressed in grams per mole, times 1/TPIV, expressed in

moles per equivalent, used as an appropriate factor.

56.1 g

mol

------ X ------ = 56.1 g/Eq

mol

1 Eq

b. **Example 2**. Find the GEW of CaCO3.2H2O.

Water, being a relatively neutral substance, is not considered when

determining the TPIV of a hydrate. However, its weight must be considered

when determining the GMW.

CaCO3.2H2O

Ca

40.1 X 1 = 40.1

C

12.0 X 1 = 12.0

O

16.0 X 3 = 48.0

H

1.0 X 4 =

4.0

O

16.0 X 2 = + 32.0

136.1 g/mol

Multiply the GMW, expressed in grams per mole, times the 1/TPIV, expressed

in moles per equivalent, used as an appropriate factor.

136.1 g

mol

-------- X -------- = 68.05 g/Eq

mol

2 Eq

c. **Example**. Calculate the GEW of Fe2(SO4)3.

The iron in ferric sulfate is ambivalent. The term ambivalent refers to the

iron's ability to have more than one valence. In order to determine the TPIV

of this and like compounds it is necessary to examine the charge of the anion

(negative ion). The TPIV will be equal to the absolute value (integer value,

excluding the sign) of the negative charge of the anion.

MD0837

4-3