Mohamn-iad Abu Yousuf (Co-Supervisor) Associate Professor, Department of Chemistry Khulna University of Engineering & Technology Head. No significant change in viscosity observed for NH4Cl with increase in molality in aqueous and in 20% aqueous DMSO solutions.
Introduction
Chemistry of Ammonium Chloride
Ammonium chloride is a stable crystalline salt of the tetrahedral NH ion, it is soluble as an alkali metal salt. When Nessler's reagent is added to an ammonium salt or ammonium chloride solution, a brown precipitate forms.
Chemistry of Nickel (II) Chloride
Nickel chloride is an excellent water-soluble crystalline nickel source for applications compatible with chlorides. If an aqueous solution of a nickel chloride base is prepared with NH4OH and then an excess solution of dimethylglyoxime is added.
Chemistry of Ferric Chloride
Hydrated ferric chloride is prepared by the action of dilute hydrochloric acid on iron (III) oxide or hydroxide. Ferric chloride is a mild reducing agent, so ferric chloride is reduced to ferric salt by the action of reducing agents such as nascent hydrogen, hydrogen sulfide stannous chloride, sulfur dioxide, etc.
Dimethyl sulfoxide
Among the more important biological consequences of this indirect effect of DMSO, we can mention changes in the conformations and associations of proteins and other molecules. When studying the alkaline hydrolysis of methyl iodide in the presence of hydroxyl ion in DMSO water, the rate of hydrolysis increases with increasing DMSO content.
The phenomena of solute-solvent interaction
It has also been found to depend on the distance of closest approach of ions in ion pairs. This indicates that some of the cations are solvated or interact strongly with solvent molecules.
Structure of liquid water
The structural changes in the solvent can be crucial for the study of the role of water in the biological system. The introduction of a solute causes changes in the properties of the liquid water, which are analogous to those caused by changes in temperature or pressure.
Physical Properties and chemical constitutions
The density of a fluid is defined as the mass of a unit volume of the fluid. An increase in temperature of a liquid increases the volume of the liquid slightly, causing its density to decrease slightly.
Molarity and Molality
This causes the liquid to expand, reducing the number of molecules per unit volume and thus the density. The molarity (m) of a solution is defined as the number of moles of solute per 1000 g of solvent.
Molar volume of solutions
The concentration dependence of the apparent molar volume of electrolytes has been described by the Masson equation [63], the Redlich-Mayer equation [60] and the Owen-Brinkley equation [61]. Masson [63] found that the apparent molar volume of electrolytes varies with the square root of the molar concentration as, .
- Viscosity
- Viscosity Coefficients A and B
Because fluid viscosity is usually very low, it is usually expressed in millipoises (mP) or centipoises (cP). When a liquid flows through a narrow tube, it is likely that the thin layer of liquid in contact with the wall is stationary; therefore, due to viscosity, the next layer will be slowed down to some extent, and this effect will continue to the center of the tube, where the flow is greatest. The velocity of liquid flow under a given pressure will obviously be lower the smaller the radius of the pipe, and the connection between these quantities was first derived by J.L.M.
If a liquid of viscosity coefficient (i) flows at a uniform rate, at a rate of V cm3 in t seconds. Driving pressure P=hg, where h is the difference in height of the surface of the two tanks, since the external pressure is the same on the surface of both tanks, g = acceleration due to gravity, and = density of the liquid. By adding the value of and of the experimental liquids/solutions and the value of the viscometric constant A into equation (2.33), we can obtain the viscosity coefficient for the liquid at a given temperature.
The viscosity of a solution relative to that of the pure solvent is called relative viscosity which is a measure of the change in the viscosity of the pure solvent as a result of the addition of solute to the solvent. Later, Falkenhagen and Dole [66] attacked the problem of the viscosity of electrolyte solutions and proposed that the electric forces between ions in the solution tend to establish and maintain a preferred rearrangement and thus to 'stiffen' the solution, i.e.
The concentration dependence of viscosity of electrolytes in aqueous solutions are
- General Techniques
- Analytical Techniques
- Preparation and Purification of Reagents
- Density measurements
During this work, several techniques were included that were generally standard. The inner wall of the viscometer was thoroughly cleaned with warm chromic acid so that there were no obstacles in the capillary and the liquid could flow clearly without leaving a drop behind. It was then thoroughly rinsed with distilled water, then with rectified alcohol and finally with acetone and dried.
The density of the solutions was determined by weighing a certain volume of the solution in a pycnometer at a certain temperature. The volumes were obtained by measuring the weight of water at this temperature and using the density of water from the literature. The pycnometer was first thoroughly cleaned with warm chromic acid and then with sufficient distilled water.
It was then rinsed with acetone and finally dried at 850C for more than two hours. When the solution began to gain the temperature of the bath, the excess liquid passed through the capillary.
- Apparent molal volume measurements
- Viscosity measurements
- Coefficient A and B determinations
The viscosity of water, DMSO and some electrolyte solutions was measured using a standard British Ostwald viscometer type U. The viscometer was then clamped vertically in the thermostatic water bath so that the top mark of the top bulb was well below the water level. It is then left to stand in the thermostatic bath for about 30 minutes to reach bath temperature.
Using a clean rubber tube attached to the narrower limb of the viscometer, the water was aspirated above the upper mark of the bulb. The reading at each temperature was repeated three or four times to check the reproducibility of the flow time, while maintaining the temperature at the same value. Since the accurate viscosity and density of water at different temperatures are known (from literature), calibration constant A of the viscometer for different temperatures was obtained using equation (1.35).
By adding the value of the calibration constant, density and flow time of the experimental solution, the viscosity of this solution was determined using equation (1.35). The values of coefficients A and B were obtained from the intercept and slope of the graph against kJ.
Results and Discussion
Volumetric properties of electrolyte solutions
The variation of (p ° with the molality of DMSO can be rationalized in terms of the cosphere overlap model. According to this model, the overlap of the cospheres of two similar ions or polar groups and one ion with that of a hydrophilic group always produces a positive change of volume On the other hand, overlapping of the cospheres of an ion with that of a hydrophobic group results in a negative change.
In the current ternary systems, the overlap of cospheres of DMSO-DMSO and DMSO-hydrophilic groups occurs from Zwitterion interactions. The overlap of cospheres of DMSO gives a positive change in volume due to the relaxation of the electrostrictive water molecules from the cosphere to the bulk. The overlap of the cospheres of DMSO with those of hydrophilic salt groups results in positive volume changes.
The positive volume change due to the overlap of the DMSO cospheres with those of the hydrophilic salt groups outweighs the negative volume change due to the overlap of the DMSO cospheres and the hydrophobic salt groups (negligible), giving a higher value of q ° in DMSO compared to that in water. This is most likely due to strong solute–solute interactions at higher DMSO concentration, where orientations of polar groups are restricted.
Viscometric properties of electrolyte solutions
Usually the positive value of the coefficient B corresponds to the structure-forming behavior of solutes. Because the molecular mass of the salt is relatively large, it can exhibit a dragging effect, bending the streamlines around a large solute particle. The B coefficient values of the above electrolytes in aqueous solutions are based on the fact that around an ion there exists a modified solvent region that differs in structure and properties from the bulk.
As the freedom of movement of these molecules is restricted, this generally results in solidification of the solution and the increment will again be positive, r D is the change in viscosity associated with the distortion of the solvent structure leading to greater fluidity. In mixed solvents, 11 D is large in magnitude due to significant distortion in the solvent molecules present. The table shows that NiCl2 and FeCl3 in aqueous solution have large positive values of B.
According to Gurney, there is a critical radius above which the ion's electric field is too weak to create order in water. This type of ions should ignite into such a cavity without disturbing the water structure [primary and secondary hydration layers around this cavity]. This disruption should result in a weakening of the bonds that hold this water molecule together in the hydration layer.
DMSO-electrolyte and DMSO-DMSO interactions gradually improve the overall structure of the solution as DMSO molality increases, reflecting an increase in the value of the B coefficient with DMSO molality. The coefficient A represents solute-solvent interactions together with the effect of solute size and shape and to some extent solute-solvent interactions. The structural property of DMSO and electrolytes for water can move away from the protein-enzyme interaction region, thereby causing protein-protein interaction and thus denaturation of the protein/enzymes.
List of the symbols and abbreviations
