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NO Acid not formed from oxide; but
aqueous solution of acid boiled
gives the oxide. HNO.AZ
1,02 Oxide dissolves in water to form a
solution of the acid. HNO3
NOG Oxide reacts with water to form the
acid; oxide also obtained from the acid by withdrawing water,
but not by action of heat. H.H,PO,Aq
No oxide known corresponding to
acid. HZ.HPO,Aq P,03! Oxides interact with water to form HPO3, H.PO., HP,0, PCOS the acids; oxides not obtained
by heating the acids. HVO3, H.V,0, (also salts V,05 Acids not obtained directly from of form M,V04)
oxide; oxide obtained by heating
the acids. Salts of form MAso, and As,0g Solution of oxide in water interacts M,AsOy
with alkalis &c. to form salts. HAsO3, H.AsO4, H.As,O, As,O, Acids not obtained from the oxide
by action of water; oxide is
obtained by heating the acids. No definite acid of Nb, only hydrates
Nb, 0.61,0; Nb,05 Oxide obtained by heating the hy. most salts are complex,
drates; hydrates not obtained may be represented as
directly from the oxide. «Nb,05.yRO where
RO=KO, CaO, &c. H2SbO2 (also salts of form Sb,02 Acid not obtained directly from MSb02)
oxide; oxide formed by beating
the acid. HSb03, H2Sb04, H,Sb,O, Sb,0, Acids not obtained directly from
oxide; oxide formed by heating
the acids. H,Ta,0, (also salts of Ta,0, Acid not obtained directly from form MTad, and various
oxide; oxide produced by heating complex salts
the acid. xTa 05.YRO)
No acids, or salts derived from acids, of didymium, erbium, or bismuth, have been isolated.
The symbol Aq here signifies that the acid to the formula of which it is added exists only in aqueous solution, and has not been isolated as a solid.
Hyponitrous acid (HNO) and nitrous acid (HNO.) act as reducing agents; they readily combine with oxygen to produce nitric acid. Nitric acid on the other hand is very frequently used as an oxidiser ; when heated it is decomposed to water, oxygen, and nitrogen dioxide (2HNO, = H,0 + 2NO, +O). All the nitrogen acids are monobasic.
When aqueous solutions of hypophosphorous acid (H. PO,) and phosphorous acid (H.PO.) are boiled, phosphine (P8) is evolved, and phosphoric acid (H,PO.) remains in solution. The three phosphoric acids, ortho- H PO, meta- HPO,, and pyro- H P,0,, may be formed by adding water to phosphoric anhydride PO, (s. Chap. XI., par. 215). Hypophosphorous acid is monobasic, and phosphorous acid is dibasic. Of the three phosphoric acids, orthophosphoric H PO, forms the largest number of definite salts: sodium pyrophosphate, Na P,0,, is obtained by heating ordinary sodium phosphate (2Na HPO, = H,0 + Na P,0z); sodium metaphosphate, NaPO, may be obtained by heating sodium-ammonium phosphate (Na(NH2HPO = H2O + NH + NaPO). When orthophosphoric acid is heated to 230° or so pyrophosphoric acid is obtained (2H PO = H,0+ H P,0,), at a red heat metaphosphoric acid is produced (H PO =X0+ HPO,). When metaor pyro-phosphoric acid is boiled with water orthophosphoric acid is produced.
Metavanadic acid HVO, and pyrovanadic acid H.V.0,, are prepared, indirectly, from salts of these acids. Besides the salts of these acids, numerous polyvanadates (or condensed vanadates) exist; the following are given as examples, Na V O,,, SrVO
No arsenious acid has been isolated. An aqueous solution of arsenious oxide (As 03) may contain arsenious acid; when this solution is neutralised with soda the salt NaAso, is obtained; by adding silver nitrate to an aqueous solution of As Oy, Ag, Aso, is precipitated. The arsenites are unstable salts, their composition seems to change with small variations in the conditions of their formation. Arsenic acid, H, AsO is formed by oxidising Aso, in presence of water, either by nitric acid or by chlorine, and crystallising. This acid loses water at 150° or so with formation of pyro-arsenic acid (2H_AsO,= H,0+ H As,O), and at about 210° water is again evolved and meta-arsenic acid remains
(H,As,0,= H,0 + 2HAsOz).
Both meta- and pyro-arsenic acids are at once changed to the ortho-acid by solution in water.
Antimonious oxide dissolves in hot caustic soda solution; from this solution the salt NaSb0, is obtained on cooling. Ortho-antimonic acid H,SbO, is produced, indirectly, from tartar emetic, KSbC,H,O,. The antimonites are easily oxidised; they are unstable and easily undergo change.
Antimonic acid, H Sb0, is obtained by adding a little water to SbCl, and drying the solid thus obtained over sulphuric acid; at 100° water is evolved and pyro-antimonic acid, H,Sb,On, remains, and at 200° this acid again loses water with production of meta-antimonic acid, HSbO. These acids seem all to exist in aqueous solution ; salts derived from HSbOg and H Sb, 0,, but not from H Sbo, are known.
Salts are obtained by replacing the hydrogen of various acids by the elements vanadium, didymium, erbium, or bismuth. The salts of didymium and erbium have not been much studied; they seem to belong to the form M 3X, where X=SO, 2NO,, &c. Vanadium pentoxide, vos interacts with alkalis to produce salts of the form M VO ; but it also interacts with sulphuric acid, and with a few other acids, to produce basic salts, e.g. (VO),(SO )3.
Vanadium tetroxide, VO, also interacts with sulphuric acid to form the salt
Bismuthous oxide, Bi, 0, forms a series of salts by interacting with acids; these salts belong to the form Bi 3X (X=80, 2NO, PO,, &c.), e.g. Bi 350, Bi6NO,, BIBO BiAso,. Most of these salts are decomposed by water with formation of basic salts; the composition of some of these basic salts is represented by the general formula BiOX where X=NO, SO.
4, &c.; but many others are more complex, and their composition can be expressed only by such a formula «Bi,O, YR. H,0 where R ==an acidic oxide, e.g. NO, SO, &c.
The elements of Group V. shew a gradual change of properties from the decidedly negative nitrogen to the metallic bismuth. Various small sub-classes appear in the group; thus arsenic and antimony are very closely related; so are niobium and tantalum ; nitrogen and phosphorus also are very similar in many chemical properties. Vanadium appears to be more distinctly metallic in its chemical properties than the
elements which succeed it in the even-series, but it is to be
Au=197 Even-series elements, and second mem- LITHIUM
POTASSIUM. RUBIDIUM. CAESIUM. ber of odd.
series Atomic weights
their molecular weights are unknown. Sp. grs. (approx.)
269-27° (approx.) Atom. weights
166 not determined. not determined. Appearance and Silver-white; Silver-white; White; soft; Silver-white; Silver-white; general physical very soft; fairly soft; very duc- brittle at 0°; soft as wax at soft. properties. ductile; not tile at 0°; can be malleable at -10°
very tenacious; distilled at red- abt. 5o; pasty at
15°; can be dis-
tilled at 700° —
800°. Occurrence and Silicate and Chloride, sili- Nitrate, sul- Compounds Silicate occurs preparation. phosphate cate, fluoride, phate, silicate, occur very as a rare mine
occur with same nitrate, &c., &c. occur in widely distri- ral.
ties of some family. widely distri- buted.
quantities, in compounds Compounds are buted.
Prepared by de- most minerals occur in many widely distri- Prepared by oxidising K2CO3 containing salts rocks and buted, but in deoxidising by hot carbon. of K and Na. waters. small quantiNa2CO3 by hot
Prepared by de- Prepared by ties, in rocks, carbon.
oxidising electrolysing water, plants,
Rb2C0g by hot fused caesiumand some ani
NH4Cl. General chemical Combines di- Oxidises rapidly Oxidises very Oxidises so ra- Exceedingly properties. rectly with oxy- in air.
rapidly in air. pidly in air that rapidly and gen, but not so Decomposes Decomposes
usually takes completely oxirapidly as other cold water ra- cold water very fire.
dised in air. elements of the pidly with evo- rapidly with Very rapidly de- Properties not family.
lution of H and production of composes cold yet much invesDecomposes production of KOHAq and water, giving tigated. cold water NaOHAq. H; H usually RbOHĂq giving LiOHAT
and H. and H.