General Chemical Relationships
363
Table A.1.1. Formula weights, equivalent weights, and conversion factors for some
common ions found in inland waters.
To convert ppm to
Formula
Equivalent
epm, or mg/l to
Ion
weight
weight"
meq,ll, multiply by:
Cations
AI3+
26.98
8.99
0.111
Fe 3+
55.85
18.6
0.0537
Fe2+
55.85
27.9
0.0358
Pb2+
207.20
104.0
0.00965
Sr2+
87.62
43.8
0.0228
Zn2+
65.37
32.7
0.0306
Cu2+
63.55
31.8
0.0315
Mn 2 +
54.94
27.5
0.0364
Ca2+
40.08
20.0
0.0499
Mg2+
24.31
12.2
0.0823
K+
39.10
39.1
0.0256
Na+
22.99
23.0
0.0435
NH4+
18.04
18.0
0.0554
H+
1.008
1.01
0.992
Anions
P0 4 3 -
94.97
31.7
0.0316
SO/96.06
48.0
0.0208
CO/60.01
30.0
0.0333
HC0 3 -
61.02
61.0
0.0164
N0 3 -
62.01
62.0
0.0161
Cl35.45
35.5
0.0282
OH17.01
17.0
0.0588
a Rounded to three significant figures.