Barium activity number

Mercerized sample absorbs barium hydroxide (alkali) to a greater degree than sodium hydroxide and from practical point of view, barium hydroxide is more easy to estimate. The ratio of uptake for this reagent has been referred to barium activity number. 

2 g mercerized and unmercerized samples are placed separately in two conical flask containing 30 ml of N/4 barium hydroxide and left for 2 h or preferably overnight. 10 ml of clear solution is withdrawn and titrated against N/10 HCl using phenolphthalein as indicator. A blank titration is also carried out on the measured barium hydroxide solution using Methyl Red as indicator. 

For exact estimation, correction should be made for the moisture regain of the sample. Barium activity number of unmercerized cotton is considered as 100 and semi-mercerized cotton ranges between 115 to 130 and that for completely mercerized cotton is about 155. 

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In the mercerization process, cotton fabrics are usually treated with 20% NaOH solution under tension. Its purpose is to enhance the fabric s characteristics such as dye affinity, dimensional stability, tensile strength, and lustre [8,9]. The process must be controlled to ensure fabric quality. Dye shade variation is the most common quality problem related to mercerized fabrics. The conventional method for determining the degree of mercerization, barium activity number (BAN), is laborious and requires 6 h before a result is obtained, which makes the test unsuitable for process control. Determining the BAN has been the only accepted method for measuring the degree of mercerization. The BAN of mercerized fabric is determined by boiling the samples of mercerized and unmercerized fabrics in... 

According to the Lewis theory, alkaline earth metal hydroxides are weaker bases than their oxides, the order of the strength of the basic sites being Ba(OH)2> SrO(OH)2 > Ca(OH)2 > Mg(OH)2. The hydroxides have been used recently as solid catalysts for organic transformations, such as the conjugate addition of methanol to a, S-unsaturated carbonyl compounds (12), cyanoethylation of alcohols (163,164), and transesterification reactions (166,167,171,172) which are described above. The extensive work of Sinisterra et al. (282) on the number and nature of sites and on the catalytic activity of the most basic alkali metal hydroxide, Ba(OH)2, is emphasized. It was found that commercial barium hydroxide octahydrate can be converted into... 

MacNevin and Ogle (87) investigated the effects of impurities on the photochromism of barium and calcium titanates as shown in Table V. Pure samples of barium and calcium titanate were not photochromic and doping with Ag+1, Cu+2, Sb+3, Sn+4, Zn+4, and Co+2 produced no enhancement of photochromism. However, increases in the concentrations of impurities such as Fe+3, Zn+2, Sb+5, and V+6 promote photochromic activity. MacNevin and Ogle concluded that the photochromism in these systems depends on the insertion into the lattice of an impurity ion having, (a) an ionic radius near that of Ti+4, and (b) an oxidation number other than 4 to make electron transfer possible. 

Barium is a member of the alkaline earth metals. The alkaline earth metals make up Group 2 (IIA) of the periodic table. The other elements in this group are beryllium, magnesium, calcium, strontium, and radium. These elements tend to be relatively active chemically and form a number of important and useful compounds. They also tend to occur abundantly in Earth s crust in a number of familiar minerals such as aragonite, calcite, chalk, limestone, marble, travertine, magnesite, and dolomite. Alkaline earth compounds are widely used as building materials. 

The method of treatment consisted in effecting a concentration of some of the constituents of the residues and observing the radioactivity of the various portions into which the material was divided. It was observed that if barium was concentrated the radioactivity of that portion increased rapidly. From a ton of residues there may be prepared 10-20 kilograms of crude sulfate whose activity is about 60 times that of uranium. The Curies then converted the sulfates to chlorides and subjected the material to the process of fractional crystallization. After a number of crystallizations there was obtained in the most insoluble portion a fraction, of a gram of radium chloride which was a million times as active as uranium, One ton of pitchblende is said to contain 0.37 gram of radium, 0.00004 gram of polonium,1 and a small amount of aetinium. 

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