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Appendix 08: Recommended Primary Standards

All compounds should be of the highest available purity. Metals should be cleaned with dilute acid to remove any surface impurities and rinsed with distilled water. Unless otherwise indicated, compounds should be dried to a constant weight at 110 oC. Most of these compounds are soluble in dilute acid (1:1 HCl or 1:1 HNO3), with gentle heating if necessary; some of the compounds are water soluble.

Element

Compound

FW (g/mol)

Comments

aluminum

Al metal

26.982

 

antimony

Sb metal

121.760

 

 

KSbOC4H4O6

324.92

prepared by drying KSbC4H4O6•1/2H2O at 110oC and storing in a desiccator

arsenic

As metal

74.922

 

 

As2O3

197.84

toxic

barium

BaCO3

197.84

dry at 200 oC for 4 h

bismuth

Bi metal

208.98

 

boron

H3BO3

61.83

do not dry

bromine

KBr

119.01

 

cadmium

Cd metal

112.411

 

 

CdO

128.40

 

calcium

CaCO3

100.09

 

cerium

Ce metal

140.116

 

 

(NH4)2Ce(NO3)4

548.23

 

cesium

Cs2CO3

325.82

 

 

Cs2SO4

361.87

 

chlorine

NaCl

58.44

 

chromium

Cr metal

51.996

 

 

K2Cr2O7

294.19

 

cobalt

Co metal

58.933

 

copper

Cu metal

63.546

 

 

CuO

79.54

 

fluorine

NaF

41.99

do not store solutions in glass containers

iodine

KI

166.00

 

 

KIO3

214.00

 

iron

Fe metal

55.845

 

lead

Pb metal

207.2

 

lithium

Li2CO3

73.89

 

magnesium

Mg metal

24.305

 

mercury

Hg metal

200.59  

molybdenum

Mo metal

95.94  

nickel

Ni metal

58.693  

phosphorous

KH2PO4

136.09  

 

P2O5

141.94  

potassium

KCl

74.56  
 

K2CO3

138.21

 
 

K2Cr2O7

294.19

 
 

KHC8H4O2

204.23

 
silicon

Si metal

28.085

 
  SiO2

60.08

 
silver Ag metal

107.868

 
  AgNO3

169.87

 
sodium NaCl

58.44

 
  Na2CO3

106.00

 
  Na2C2O4

134.00

 
strontium SrCO3

147.63

 
sulfur elemental S

32.066

 
  K2SO4 174.27

 

  Na2SO4 142.04

 

tin Sn metal 118.710

 

titanium

Ti metal

47.867

 
tungsten W metal

183.84

 
uranium U metal

238.029

 
  U3O8

842.09

 
vanadium

V metal

50.942  
zinc

Zn metal

81.37  

Sources: (a) Smith, B. W.; Parsons, M. L. J. Chem. Educ. 1973, 50, 679–681; (b) Moody, J. R.; Greenburg, P. R.; Pratt, K. W.; Rains, T. C. Anal. Chem. 1988, 60, 1203A–1218A.