Acids, bases and buffer solutions

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
First Principles ◽  
Buffer Capacity ◽  
Unique Feature ◽  
Dissociation Constants ◽  
Equilibrium Composition ◽  
Buffer Solutions ◽  
Acid And Base ◽  
Water Ph ◽  
Acids And Bases ◽  
Conjugate Bases

Many reactions in solution involve acids and bases, and so this chapter examines these important reactions in detail. Topics covered include the ionisation of water, pH, pOH, acids and bases, conjugate acids and conjugate bases, acid and base dissociation constants, the Henderson-Hasselbalch equation, the Henderson-Hasselbalch approximation, buffer solutions and buffer capacity. A unique feature of this chapter is a ‘first principles’ analysis of how a reaction buffered at a particular pH achieves an equilibrium composition different from that of the same reaction taking place in an unbuffered solution. This introduces some concepts which are important in understanding the biochemical standard state, as required for Chapter 23.

THE SULPHURIC ACID SOLVENT SYSTEM: PART I. ACID-BASE REACTIONS

1960 ◽  
Vol 38 (8) ◽  
pp. 1363-1370 ◽  
Author(s):  
R. H. Flowers ◽  
R. J. Gillespie ◽  
E. A. Robinson
Keyword(s):  
Electrical Conductivity ◽  
Sulphuric Acid ◽  
Dissociation Constants ◽  
Solvent System ◽  
Conductivity Measurements ◽  
Acid Base ◽  
Acid And Base ◽  
System Part ◽  
Acids And Bases ◽  
Good Agreement

Acid–base reactions in the solvent sulphuric acid are discussed. Such reactions are conveniently studied by electrical conductivity measurements. A relation between the composition at which the conductivity has a minimum value and the strengths of the acid and base is derived. Values of the dissociation constants of acids and bases obtained in this way are shown to be in good agreement with values obtained by other methods.

Reactions in solution

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Phase Equilibria ◽  
Gas Phase ◽  
First Principles ◽  
Unique Feature ◽  
Life Sciences ◽  
Equilibrium Mixture ◽  
Second Law ◽  
Ideal Solution ◽  
Coupled Reactions ◽  
Definition Of

Another key chapter, examining reactions in solution. Starting with the definition of an ideal solution, and then introducing Raoult’s law and Henry’s law, this chapter then draws on the results of Chapter 14 (gas phase equilibria) to derive the corresponding results for equilibria in an ideal solution. A unique feature of this chapter is the analysis of coupled reactions, once again using first principles to show how the coupling of an endergonic reaction to a suitable exergonic reaction results in an equilibrium mixture in which the products of the endergonic reaction are present in much higher quantity. This demonstrates how coupled reactions can cause entropy-reducing events to take place without breaking the Second Law, so setting the scene for the future chapters on applications of thermodynamics to the life sciences, especially chapter 24 on bioenergetics.

scholarly journals The pH measurement with glass electrode in an electromagnetic field

2016 ◽  
Vol 81 (12) ◽  
pp. 1407-1414 ◽  
Author(s):  
Dragan Veselinovic ◽  
Zoran Velikic
Keyword(s):  
Electromagnetic Field ◽  
Buffer Capacity ◽  
Extreme Values ◽  
Ph Value ◽  
Radiation Power ◽  
Glass Electrode ◽  
Frequency Interval ◽  
Buffer Solutions ◽  
Ph Values ◽  
Glass Electrodes

Measurements of pH values of buffer solutions (pH 4.0, 7.0 and 10.0) and distilled water have been performed with a glass electrode in electromagnetic field at the frequency interval of 10 MHz to 200 MHz and the output power of dispersed and reflected electromagnetic radiation of 0.01 W to 3 W. In all the cases, there occurred a reduction of pH values, i.e. a "recorded pH value" was obtained. The reduction appears within the applied frequency interval reaching extreme values at specific frequencies. The reduction of the pH values increases with the radiation power and depend of the solution buffer capacity. The effect of electromagnetic field on pH value change is exerted dominantly through the influence on glass electrodes.

scholarly journals The-Proof-of-Concept of Biochar Floating Cover Influence on Water pH

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1802 ◽  
Author(s):  
Zhanibek Meiirkhanuly ◽  
Jacek A. Koziel ◽  
Andrzej Białowiec ◽  
Chumki Banik ◽  
Robert C. Brown
Keyword(s):  
Buffer Capacity ◽  
Corn Starch ◽  
Tap Water ◽  
Spatial And Temporal Variation ◽  
Gaseous Emissions ◽  
Inorganic Contaminants ◽  
Ph Indicator ◽  
Ph Change ◽  
Air Interface ◽  
Water Ph

Studies have shown that biochar has the potential to remove organic and inorganic contaminants from wastewater. pH is known to have a crucial role in the transformation of pollutants. In this research, we explore the feasibility of using biochars properties to control the pH near the water–air interface, so the gaseous emissions from water (or wastewater) could be mitigated. This study aimed to test the effects of a thin layer biochar addition on the spatial and temporal variation of water pH. Two types of biochar and water were tested. Highly alkaline porous (HAP; pH 9.2) biochars made of corn stover and red oak (RO; pH 7.5) were applied surficially to tap (pH 9.5) and deionized water (DI) (pH 5.4). The spatial pH of solutions was measured every 1 mm of depth on days 0, 2, and 4 after biochar application. The results showed that HAP biochar increased the pH of both tap and DI water, while RO decreased tap water pH and increased DI water pH. On day 0, there was no effect on tap water pH, while a pH change in DI water was observed due to its lower buffer capacity. In addition, the pH (temporal) migration from topically applied biochar into an aqueous solution was visualized using a colorimetric pH indicator and corn starch to increase viscosity (to prevent biochars from sinking). The results prove that the surficial application of biochar to water was able to change both the pH near the water–air interface and the pH of the solution with time. The pH change was dependent on the biochar pH and water buffer capacity. These results warrant further research into the floatability of biochars and into designing biochars with specific pH, which could be a factor influencing gaseous emissions from liquids that are sensitive to pH.

scholarly journals Acid strength and its dependence upon the nature of the solvent

1933 ◽  
Vol 140 (841) ◽  
pp. 440-451 ◽  
Keyword(s):  
Dissociation Constant ◽  
Ethyl Alcohol ◽  
Dissociation Constants ◽  
Acid Strength ◽  
Suitable Choice ◽  
Satisfactory Solution ◽  
Nitrobenzoic Acid ◽  
Fundamental Assumption ◽  
Acids And Bases ◽  
Intrinsic Strength

The development of our views concerning the nature of acids and bases and, in particular, the precision given to these views by the definitions proposed by Brönsted and Lowry of an acid as a substance which splits off protons, and of a base as a substance which takes up protons, have led to a much clearer understanding of the behaviour of acids and bases in different solvents. The essential dependence of the ionization of acids and bases upon the basicity or acidity of the solvent has been emphasized in a number of papers, and many authors have shown how by suitable choice of solvent a much greater range of acidity is available than when water alone is employed. Despite the very notable advances that have been made, there is a further problem, that of the relative strengths of different acids, to which a satisfactory solution has not yet been found. So far as any single solvent is concerned, it is usual to regard the dissociation constant of an acid as a measure of its strength, and on this basis numerous attempts have been made to correlate acid strength and constitution. Many of these attempts have been expressed quantitatively, and that the opinion is widely held that some such relation can be formulated is evidenced by the innumerable “proofs of structure,” which are advanced on the basis of measurements of dissociation constants. However, an examination of the data for different solvents shows that the fundamental assumption that the intrinsic strength of an acid is measured by its dissociation constant in a particular solvent is invalid, since an acid which is stronger than another in one solvent is often weaker in a second solvent; thus in water o -nitrobenzoic acid has a dissociation constant of 6·2 X 10 -3 compared with 1·6 X 10 -3 for 3·5 dinitrobenzoic acid, while in ethyl alcohol the respective constants are 2·42 X 10 -9 and 8·16 X 10 -9 . This fact, which emerges very clearly from the extensive work of Goldschmidt on solutions in methyl and ethyl alcohols and is confirmed by the work of Larsson and of Halford, means that it is impossible to transfer a scale of acidity from one solvent to another, and renders of doubtful significance the rules previously formulated on the basis of results in water

General equation for determining the dissociation constants of polyprotic acids and bases from additive properties

2001 ◽  
Vol 428 (2) ◽  
pp. 309-321 ◽  
Author(s):  
Issam Jano ◽  
James Hardcastle ◽  
Lamia A. Jano ◽  
Kami R. Bates ◽  
Heather E. McCreary
Keyword(s):  
General Equation ◽  
Dissociation Constants ◽  
Acids And Bases
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