The Foundations of Chemistry

Sulfuric acid is a diprotic acid. One molecule of H 2 SO 4 can furnish 2H
ions.

H 2 O

H 2 SO 4 8888n 2H
(aq) 
SO 42 (aq)

1 mol 2 mol 1 mol

98.08 g 2(1.008 g) 96.06 g

6.022 1023 2(6.022 1023 ) 6.022 1023

formula units formula units formula units

This equation shows that one mole of H 2 SO 4 can produce 2(6.022 1023 ) H
; there-

fore, one mole of H 2 SO 4 is twoequivalent weights in all reactions in which bothacidic

hydrogen atoms react.

One equivalent weight of a baseis defined as the mass of the base (expressed in

grams) that will furnish 6.022 1023 hydroxide ions or the mass of the base that will react

with 6.022 1023 hydrogen ions.

The equivalent weight of an acidis obtained by dividing its formula weight in grams

either by the number of acidic hydrogens that could be furnished by one formula unit of

the acid orby the number of hydroxide ions with which one formula unit of the acid reacts.

The equivalent weight of a baseis obtained by dividing its formula weight in grams either

by the number of hydroxide ions furnished by one formula unit orby the number of

hydrogen ions with which one formula unit of the base reacts. Equivalent weights of some

common acids and bases are given in Table 11-1.

EXAMPLE 11-10 Concentration of a Solution

Calculate the normality of a solution of 4.202 grams of HNO 3 in 600. mL of solution.

Plan

We convert grams of HNO 3 to moles of HNO 3 and then to equivalents of HNO 3 , which lets

us calculate the normality.

88n88n  NHNO 3

eq HNO 3



L

mol HNO 3



L

g HNO 3



L

One mole of H 2 SO 4 is two
equivalent weights of H 2 SO 4.

TABLE 11-1 Equivalent Weights* of Some Acids and Bases

Acids Bases

Symbolic Symbolic

representation One eq representation One eq

63.02 g HNO 3 40.00 g NaOH

60.03 g CH 3 COOH 17.04 g NH 3

204.2 g KHP 37.05 g Ca(OH) 2

49.04 g H 2 SO 4 85.68 g Ba(OH) 2

*Complete neutralization is assumed.

171.36 g



2

Ba(OH) 2



2

98.08 g



2

H 2 SO 4



2

74.10 g



2

Ca(OH) 2



2

204.2 g



1

KHP



1

17.04 g



1

NH 3



1

60.03 g



1

CH 3 COOH



1

40.00 g



1

NaOH



1

63.02 g



1

HNO 3



1