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preface to fifteenth edition

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11.94 SECTION 11<br />

TABLE 11.30<br />

Standard Solutions for Precipitation Titrations<br />

The list given below includes the substances that are most used and most useful for the standardization of<br />

solutions for precipitation titrations. Primary standard solutions are denoted by the letter (P) in Column 1.<br />

Standard<br />

Formula<br />

weight<br />

Preparation<br />

AgNO 3 (P) 169.89 Weigh the desired amount of ACS reagent grade* AgNO 3 , dried at<br />

105C for 2 hr, and dissolve in double distilled water. S<strong>to</strong>re in amber<br />

container and away from light. Check against NaCl.<br />

BaCl 2 ·2H 2 O 244.28 Dissolve clear crystals of the salt in distilled water. Standardize against<br />

K 2 SO 4 or Na 2 SO 4 .<br />

Hg(NO 3 ) 2 ·H 2 O 342.62 Dissolve the reagent grade salt in distilled water and dilute <strong>to</strong> desired<br />

volume. Standardize against NaCl.<br />

KBr 119.01 The commercial reagent (ACS) may contain 0.2% chloride. Prepare an<br />

aqueous solution of approximately the desired concentration and standardize<br />

it against AgNO 3 .<br />

K 4 [Fe(CN)] 6 ·3H 2 O 422.41Dissolve the high-purity commercial salt in distilled water containing<br />

0.2 g/L of Na 2 CO 3 . Kept in an amber container and away from direct<br />

sunlight, solutions are stable for a month or more. Standardize against<br />

zinc metal.<br />

KSCN 97.18 Prepare aqueous solutions having the concentration desired. Standardize<br />

against AgNO 3 solution. Protect from direct sunlight.<br />

K 2 SO 4 (P) 174.26 Dissolve about 17.43 g, previously dried at 150C and accurately<br />

weighed, in distilled water and dilute exactly <strong>to</strong> 1L.<br />

NaCl (P) 58.44 Dry at 130–150C and weigh accurately, from a closed container, 5.844<br />

g, dissolve in water, and dilute exactly <strong>to</strong> 1L.<br />

NaF (P) 41.99 Dry at 110C and weigh the appropriate amount of ACS reagent. Dissolve<br />

in water and dilute exactly <strong>to</strong> 1L.<br />

Na 2 SO 4 (P) 142.04 Weigh accurately 14.204 g, dried at 150C, and dissolve in distilled<br />

water. Dilute <strong>to</strong> exactly 1L.<br />

Th(NO 3 ) 4 ·4H 2 O 552.12 Weigh the appropriate amount of crystals and dissolve in water. Standardize<br />

against NaF.<br />

* Meets standards of purity (and impurity) set by the American Chemical Society.

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