Silver In Aqueous Solution Research Articles

An examination of the atomic absorption spectroscopy of silver

Silver in aqueous solution in the range 1–10 ppm is determined by direct atomic absorption spectroscopy in an air/propane flame at 3281 Å. Many potential interferences are examined; only thorium, iodate, tungstate and permanganate cause interference when present in 1000-fold mole-ratio excess. Silver can also be determined without interference from any known ion in the range 0.1 down to 0.01 ppm in aqueous solution following an extraction of the silver as its di-n-butylammonium salicylate into methyl isobutyl ketone. The extract is submitted directly to absorptiometry in the flame. The solvent enhancement effect is shown to be caused principally by an increase of atomisation relative to aqueous solution.

Determination of the Value of the Faraday With a Silver-Perchloric Acid Coulometer.

An accurate value of the faraday has been determined by the electrolytic dissolution of metallic silver in aqueous solutions of perchloric acid. Standards of electric current, mass, and time as maintained by the National Bureau of Standards were utilized in the determinations. The electric current was measured in terms of the standards of electromotive force and electrical resistance. Silver of high purity, freed from oxygen, was used.The value of the faraday was found to be faraday=96516.5±2.4coulombsgram-equivalent−1(physicalscale),faraday=96490.0±2.4coulombsgram-equivalent−1(chemicalscale).These values were obtained using 107.9028±0.0013 and 107.8731±0.0013, for the atomic weight of silver on the physical and chemical scales, respectively.The electrochemical equivalent of silver was found to be electrochemical equivalent of silver=1.117972±0.000019milligram coulomb−1.This value may be used in an alternate method of defining the ampere in absolute value, namely, that steady current which will dissolve 1.117972 milligrams of silver per second and depends only on the standards of mass and time. The indicated uncertainties are overall limits of error based on 95 percent confidence limits for the mean and allowances for the effects of known sources of possible systematic error.

Stability of Silver and Pyrex in Perchloric Acid-Silver Perchlorate Solutions and in Conductivity Water.

The stability of mint silver, purified mint silver, and Pyrex fritted crucibles in aqueous solutions of perchloric acid, in aqueous solutions of perchloric acid containing silver perchlorate, and in conductivity water at room temperature was determined. The stability of the silver in various states of subdivision was studied. The corrosion current-density for mint silver in sheet form is 1.1 × 10−8 amp cm−2 for 20 percent aqueous solutions of perchloric acid, 1.3×10−9 amp cm−2 for 20 percent aqueous solutions of perchloric acid containing 0.5 percent silver perchlorate, and within the limits of detection is zero for conductivity water. Pyrex has high stability at 25° C in 20 percent aqueous solutions of perchloric acid and in 20 percent aqueous solutions of perchloric acid containing 0.5 percent silver perchlorate. Finely-divided silver contained in Pyrex crucibles was found to be highly stable when the crucibles were filled repeatedly with aqueous solutions of perchloric acid containing silver perchlorate, rinsed with conductivity water, and dried at 105° C. These observations are important in the determination of the faraday by the anodic dissolution of silver in aqueous solutions of perchloric acid which is now underway at the National Bureau of Standards.