Dilution of Concentrated Solutions

12 Given any three of the following, calculate the fourth (a) volume of concentrated solution, (b) molarity of concentrated solution, (c) volume of dilute solution, (d) molarity of dilute solution. 

Equation 16.11 has two important applications. They are illustrated in the next two examples. 

How many milliliters of commercial hydrochloric acid, which is 11.6 molar, should you use to prepare 5.50 liters of 0.500 M HCl  

H A 100.0-mL volumetric flask has been filled to the mark with a 0.100 M l 2Cr207 solution. 

Q The 1.000-L flask is then filled with distilled water to the mark on the neck, and shaken thoroughly. The concentration of the now-diluted solution is 0.0100 M. 

---

Ions not solvated are unstable in solutions between them and the polar solvent molecules, electrostatic ion-dipole forces, sometimes chemical forces of interaction also arise which produce solvation. That it occurs can be felt from a number of effects the evolution of heat upon dilution of concentrated solutions of certain electrolytes (e.g., sulfuric acid), the precipitation of crystal hydrates upon evaporation of solutions of many salts, the transfer of water during the electrolysis of aqueous solutions), and others. Solvation gives rise to larger effective radii of the ions and thus influences their mobilities. 

Rubefacients Produce redness Allyl isothiocyanate 0.5-5% Ammonia water 1 -2.5% Musterole Extra Made by dilution of concentrated solution with water Mustard derivative Pungent odor Avoid inhalation More concentrated solutions are highly caustic Avoid inhalation... 

I. Lopez-Garcia, J. Arroyo, P. Vinas, M. Hemandez-Cordoba, A manifold for the automatic dilution of concentrated solutions in flame atomic absorption spectrometry, Anal. Bioanal. Chem. 372 (2002) 587. 

Irrigations have various uses, and therefore various users. Not only the one who prepares and dispenses them should know their purpose, but also the patient or the professional caregiver. Solutions for the different types of dialysis form a separate category. Surveillance and monitoring of the whole process, but especially the quality management of the installation for the production of water for the dilution of concentrated solutions, are often more difficult than the preparation of the concentrates themselves. 

To make diluted solutions, chemists use volumetric flasks or beakers for accurate measuring. With a bit of practice, making dilutions of concentrated solutions right off the shelf will be a snap. 

Dilution of concentrated solution to make less-concentrated solution (Section 7.5) (CJ(K) = (Q)(FJ Equation 7.9... 

The equivalent conductance of a solution is a convenient chemical quantity. It is defined as the hypothetical conductance of one chemical equivalent of a dissolved substance A = a iV ixe, where a is the fraction of the dissolved substance (solute) in the ionic form, and iV , A, and e are, respectively, Avogadro s number, the ionic mobility, and the elementary charge. The equivalent conductance is related to the conductance a = /xe hy the relation A = 1000 a/c, where c is the solute concentration in moles per liter. With solvents of dielectric constant greater than 30, solutions of simple electrolytes generally may be expectd to be fully ionized at all concentrations, i.e., a = 1. Upon dilution of concentrated solutions in which the mobility of the ions is reduced by interionic forces, the variation of A with concentration follows the general limiting law ... 

A logical division is made for the adsorption of nonelectrolytes according to whether they are in dilute or concentrated solution. In dilute solutions, the treatment is very similar to that for gas adsorption, whereas in concentrated binary mixtures the role of the solvent becomes more explicit. An important class of adsorbed materials, self-assembling monolayers, are briefly reviewed along with an overview of the essential features of polymer adsorption. The adsorption of electrolytes is treated briefly, mainly in terms of the exchange of components in an electrical double layer. 

Freshly opened bottles of these reagents are generally of the concentrations indicated in the table. This may not be true of bottles long opened and this is especially true of ammonium hydroxide, which rapidly loses its strength. In preparing volumetric solutions, it is well to be on the safe side and take a little more than the calculated volume of the concentrated reagent, since it is much easier to dilute a concentrated solution than to strengthen one that is too weak. 

The practical problems He ia the separatioa of the chlorine from the hydrogea chloride and nitrous gases. The dilute nitric acid must be reconcentrated and corrosion problems are severe. Suggested improvements iaclude oxidation of concentrated solutions of chlorides, eg, LiCl, by nitrates, followed by separation of chlorine from nitrosyl chloride by distillation at 135°C, or oxidation by a mixture of nitric and sulfuric acids, separating the... 

Analysis for Poly(Ethylene Oxide). Another special analytical method takes advantage of the fact that poly(ethylene oxide) forms a water-insoluble association compound with poly(acryhc acid). This reaction can be used in the analysis of the concentration of poly(ethylene oxide) in a dilute aqueous solution. Ereshly prepared poly(acryhc acid) is added to a solution of unknown poly(ethylene oxide) concentration. A precipitate forms, and its concentration can be measured turbidimetricaHy. Using appropriate caUbration standards, the precipitate concentration can then be converted to concentration of poly(ethylene oxide). The optimum resin concentration in the unknown sample is 0.2—0.4 ppm. Therefore, it is necessary to dilute more concentrated solutions to this range before analysis (97). Low concentrations of poly(ethylene oxide) in water may also be determined by viscometry (98) or by complexation with KI and then titration with Na2S202 (99). 

A finite time is required to reestabUsh the ion atmosphere at any new location. Thus the ion atmosphere produces a drag on the ions in motion and restricts their freedom of movement. This is termed a relaxation effect. When a negative ion moves under the influence of an electric field, it travels against the flow of positive ions and solvent moving in the opposite direction. This is termed an electrophoretic effect. The Debye-Huckel theory combines both effects to calculate the behavior of electrolytes. The theory predicts the behavior of dilute (<0.05 molal) solutions but does not portray accurately the behavior of concentrated solutions found in practical batteries. 

Povidone—iodine is a brown, water-soluble powder containing approximately 10% iodine. However, the amount of free iodine, which is responsible for the antimicrobial activity, is low in a concentrated solution, but is released as the solution is diluted (41). Concentrated solutions have actually been contaminated with bacteria (42). For use as an antiseptic, povidine—iodine is diluted with water or alcohol to a concentration of 1% iodine. Detergents are added if it is used as a surgical scmb. lodophors are important as broad-spectmm antiseptics for the skin, although they do not have the persistent action of some other antiseptics. They are also used as disinfectants for clinical thermometers that have been used by tuberculous patients, for surface disinfection of tables, etc, and for clean equipment in hospitals, food plants, and dairies, much as chlorine disinfectants are used. 

The dependence of reaction rates on pH and on the relative and absolute concentrations of reacting species, coupled with the possibility of autocatalysis and induction periods, has led to the discovery of some spectacular kinetic effects such as H. Landolt s chemical clock (1885) an acidified solution of Na2S03 is reacted with an excess of iodic acid solution in the presence of starch indicator — the induction period before the appearance of the deep-blue starch-iodine colour can be increased systematically from seconds to minutes by appropriate dilution of the solutions before mixing. With an excess of sulfite, free iodine may appear and then disappear as a single pulse due to the following sequence of reactions ... 

The advantage of preparing solutions by the method illustrated in Figure 10.1 is that only It s easier to dilute a concentrated solution... 

The titration error will increase with increasing dilution of the solution being titrated and is quite appreciable (ca 0.4 per cent) in dilute, say 0.01 M, solutions when the chromate concentration is of the order 0.003-0.005M. This is most simply allowed for by means of an indicator blank determination, e.g. by measuring the volume of standard silver nitrate solution required to give a perceptible coloration when added to distilled water containing the same quantity of indicator as is employed in the titration. This volume is subtracted from the volume of standard solution used. 

Plot the observed e.m.f. values against the concentrations of the standard solutions, using a semi-log graph paper which covers four cycles (i.e. spans four decades on the log scale) use the log axis for the concentrations, which should be in terms of fluoride ion concentration. A straight line plot (calibration curve) will be obtained. With increasing dilution of the solutions there tends to be a departure from the straight line with the electrode combination and measuring system referred to above, this becomes apparent when the fluoride ion concentration is reduced to ca 0.2 mg L-1. 

The entries were reconstructed for Eq. (3-30) from the rate constant values of kI = 0.406 s l and k 1 = 383 L mol"1 1 from Ref. 2. One calculation is for the reaction starting with A alone, and the other for a concentration-jump experiment with a two-fold dilution of a solution made up to have an original concentration of A of 2.84 X... 

One of the first scientists to place electrochemistry on a sound scientific basis was Michael Faraday (1791-1867). On the basis of a series of experimental results on electrolysis, in the year 1832 he summarized the phenomenon of electrolysis in what is known today as Faraday s laws of electrolysis, these being among the most exact laws of physical chemistry. Their validity is independent of the temperature, the pressure, the nature of the ionizing solvent, the physical dimensions of the containment or of the electrodes, and the voltage. There are three Faraday s laws of electrolysis, all of which are universally accepted. They are rigidly applicable to molten electrolytes as well as to both dilute and concentrated solutions of electrolytes. 

A solution of NaOH in water is prepared by diluting a concentrated solution in an agitated, jacketed, vessel. The strength of the concentrated solution is 50 per cent w/w and 2500 kg of 5 per cent w/w solution is required per batch. Calculate the heat removed by the cooling water if the solution is to be discharged at a temperature of 25°C. The temperature of the solutions fed to the vessel can be taken to be 25°C. 

Finally, a further unsolved problem should be mentioned. If we compare the plateau moduli of different polymer melts and relate them to the Kuhn length and to the density, this relation can also be adequately described with the scaling model, if an exponent a near 3 is chosen [73]. It is not known why this exponent is different if the contour length density is varied by dilution in concentrated solution or by selecting polymer chains of different volume. 

In either dilute or concentrated solutions, additional reactions occur that result in both intra- and intermolecular cross-linking of proteins. There is little direct chemical information from such techniques as nuclear magnetic resonance spectroscopy or mass spectrometry to detail the precise nature of these cross-links.5,6... 

In all cases, the cloud-point temperature was slightly dependent on polymer concentration for a given copolymer it increased with decreasing concentration. This effect is enhanced with increasing number of PEO grafts per chain. Also, the PNIPAM collapse seemed to be less abrupt with decreasing concentration. Upon dilution of the solution the distance between polymer chains increases, which favours intrapolymeric interactions over in-terpolymeric attractions. Dilution also enhances the surface stabilisation of the polymer particles by PEO. 

---