Aqueous solutions state

Hydrogen cyanide is highly endothermic and of low MW (AH°f (g) +130.5 kJ/mol, 4.83 kJ/g). A comprehensive guide to all aspects of industrial handling of anhydrous hydrogen cyanide and its aqueous solutions states that the anhydrous liquid is stable at or below room temperature if it is inhibited with acid (e.g. 0.1% sulphuric acid) [ ] Presence of alkali favours explosive polymerisation [2], In absence of inhibitor, exothermic polymerisation occurs, and if the temperature attains 184°C, explosively rapid polymerisation occurs [3], A 100 g sample of 95-96% material stored in a glass bottle shielded from sunlight exploded after 8 weeks [4], The explosive polymerisation of a 33 kg cylinder was attributed to lack of sufficient phosphoric acid... 

The Gd-H distance, /-GdH, which enters at the inverse sixth power into the expression of inner-sphere relaxivity, is a difficult parameter to obtain experimentally. It is generally estimated on the basis of Gd-coordinated water oxygen distances, determined by solid-state X-ray analysis. Solid-state distances are good estimates of the aqueous solution state, as was experimentally proven by an X-ray absorption fine-structure study on [Gd(D0TA)(H20)] and [Gd(DTPA)(H20)]2, which gave identical values for the Gd-0 distances for both complexes in solid and solution states.20... 

The silk production process must have some built-in temporal, mechanical, and chemical flexibility. This is evident in the ability of the animal to switch from long-duration storage of the proteins (in an aqueous solution state) to high-speed extrusion spinning (into an insoluble fiber with... 

See 6] aqueous solution state partly by photo- ring closure, not ... 

Pikal MJ, Dellerman KN. Stability testing of pharmaceuticals by high sensitivity isothermal calorimetry at 25°C cephalosporins in the solid and aqueous solution states. Int J Pharm 1989 50 233-252. 

Extraction followed by distillation is thought to be more economical than distillation alone in the case of separation of acetic acid from a dilute aqueous solution. State whether this statement is true or false. 

Sample Preparation. Pitch-based ACF is used as adsorbent. CACF was prepared by impregnating a KOH. KOH was impregnated in an aqueous solution state in the ACF via incipient wet impregnation. 

Often the physical state of substances appearing in equations is indicated by the letters (g), (1), (s), and (aq), which refer to gaseous, liquid, solid, and aqueous solution states, respectively. 

The physical state of a substance is indicated by the following symbols (s) for solid state (/) for liquid state (g) for gaseous state and (aq) for substances in aqueous solution. States are not always given in chemical equations. 

Pham TN, Watson SA et al (2010) Analysis of amorphous solid dispersions using 2D solid-state NMR and IH T 1 relaxation measurements, vol 7. ACS Publications, New York, pp 1667-1691 Pikal MJ, DeUerman KM (1989) Stability testing of pharmaceuticals by high-sensitivity isothermal calorimetry at 25 C cephalosporins in the solid and aqueous solution states. Int J Pharm 50 233-252... 

Plumbaies IV), e.g. ICjPbOj, are formed by solid state reactions and plunibates containing [Pb(OH)6] " ions are formed from aqueous solution. 

Stillinger F 1973 Structure in aqueous solutions from the standpoint of scaled particle theory J. Solution Chem. 2 141 Widom B 1967 Intermolecular forces and the nature of the liquid state Sc/e/ ce 375 157 Longuet-Higgins H C and Widom B 1964 A rigid sphere model for the melting of argon Mol. Phys. 8 549... 

Silicon, germanium, tin and lead can make use of unfilled d orbitals to expand their covalency beyond four and each of these elements is able (but only with a few ligands) to increase its covalency to six. Hence silicon in oxidation state -f-4 forms the octahedral hexafluorosilicate complex ion [SiFg] (but not [SiCl] ). Tin and lead in oxidation state -1-4 form the hexahydroxo complex ions, hexahydroxostannate(IV). [Sn(OH) ] and hexahydroxoplum-bate(IV) respectively when excess alkali is added to an aqueous solution containing hydrated tin(IV) and lead(IV) ions. 

With the outer electronic configuration 3d 4s vanadium can attain an oxidation state of -I- 5, but it shows all oxidation states between -I- 5 and -I- 2 in aqueous solution (cf titanium). 

This IS the important state of vanadium in aqueous solution it is neither strongly oxidising or strongly reducing and acidic solutions are stable to atmospheric oxidation ... 

This is the most common and stable state of chromium in aqueous solution. The Cr ion, with 2d electrons, forms mainly octahedral complexes [CrX ], which are usually coloured, and are kweticallv inert, i.e. the rate of substitution of X by another hgand is very slow consequently a large number of such complexes have been isolated (see below, under chromium(III) chloride). 

This state is unstable with respect to disproportionation in aqueous solution ... 

In contrast to the + 2 state, copper(I) compounds are less frequently coloured and are diamagnetic, as expected since the 3d level is full. However, the copper(I) ion, unlike copper(II), is unstable in aqueous solution where it disproportionates into copper(II) and copper(O) (i.e. copper metal). 

The second application of the CFTI protocol is the evaluation of the free energy differences between four states of the linear form of the opioid peptide DPDPE in solution. Our primary result is the determination of the free energy differences between the representative stable structures j3c and Pe and the cyclic-like conformer Cyc of linear DPDPE in aqueous solution. These free energy differences, 4.0 kcal/mol between pc and Cyc, and 6.3 kcal/mol between pE and Cyc, reflect the cost of pre-organizing the linear peptide into a conformation conducive for disulfide bond formation. Such a conformational change is a pre-requisite for the chemical reaction of S-S bond formation to proceed. The predicted low population of the cyclic-like structure, which is presumably the biologically active conformer, agrees qualitatively with observed lower potency and different receptor specificity of the linear form relative to the cyclic peptide. 

From the standpoint of thermodynamics, the dissolving process is the estabHsh-ment of an equilibrium between the phase of the solute and its saturated aqueous solution. Aqueous solubility is almost exclusively dependent on the intermolecular forces that exist between the solute molecules and the water molecules. The solute-solute, solute-water, and water-water adhesive interactions determine the amount of compound dissolving in water. Additional solute-solute interactions are associated with the lattice energy in the crystalline state. 

---