Reducing agents, such as sulphurous acid and sulphuretted hydrogen, convert the chromates into chromic salts.
Normal chromates on the addition of silver nitrate give a red precipitate of silver chromate, easily soluble in ammonia, and with barium chloride a yellow precipitate of barium chromate, insoluble in acetic acid.
The yellow colour of normal chromates changes to red on the addition of an acid, but goes back again to yellow on making the solution alkaline.
The chromates are stable towards heat; they are poisonous, and may be recognized by the yellow precipitates they give with soluble barium and lead salts.
The alkaline chromates are soluble in water, those of most other metals being insoluble.
The alkaline chromates are usually obtained by fusion of a chromium compound with an alkaline carbonate and an oxidizing agent, such for example as potassium nitrate or chlorate.
The majority of the chromates are yellow in colour, and many of them are isomorphous with the corresponding sulphates.
Like all the chromates of lead, it is characterized by power and brilliancy; but also by a rankness of tone, a want of permanence, and a tendency to injure organic pigments.
It is, however, much more readily oxidized than sulphate of lead; and hence the thallium chromates would doubtless soon regain their former hue on exposure to a strong light.
The chromates of lead and barium separate as yellow precipitates.
The relation between the chromates and dichromates is the same as that between the phosphates and the pyrophosphates.
Most of the chromatesare insoluble and can therefore be prepared by precipitation.
When added to a solution of lead or barium salt the correspondingchromates (not dichromates) are precipitated.
Their salts, thechromates and dichromates, are important compounds.
The chromates are characterised by their yellow or red colour, the latter predominating when the acid is in excess; and except those with the alkaline bases, they are, for the most part, insoluble in water.
The soluble chromates may all be made by direct solution of the base in the acid, or by double decomposition.
The chromates of commerce are prepared from either chrome ore or chromate of potassium.
With acetate of lead the chromates give a yellow precipitate; with nitrate of silver, a reddish-brown; with nitrate of mercury, a red one.
Detection of the Chromates and Separation of the Salts of Chromium from the Contents of the Stomach, &c.
If the chromates of strychnine and curarine be mixed, and the mixed chromates be treated with ammonia, strychnine will be precipitated, and curarine pass into solution, thus forming a ready method of separating them.
Common salt or hydrate of calcium may be substituted for chloride of potassium, when the chromates of sodium or calcium are respectively produced.
It consists in heating in a current of steam the manganates, permanganates, chromates and ferrates of the alkalies and alkaline earths, and regenerating the residue by passing air over it at a red heat.
Other chromium compounds of an entirely different type are also used in fur dyeing, these beingchromates and bichromates, the latter finding greater application than the former.
Chromates and chromic salts are generally soluble in water or dilute acids.
The chromates in solution are more stable than other similar oxidising agents, and consequently are generally used in the laboratory as one of the standard oxidising agents for volumetric analysis.
Some of the insoluble chromates are used as pigments; chromate of lead or chrome-yellow is the most important.
Chromates are reduced to chromic salts by the action of most reducing agents in the presence of an acid; and this property is used in assaying for the volumetric determination of ferrous iron, &c.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "chromates" in a variety of sentences. We hope that you will now be able to make sentences using this word.
