Hydrogen Ion Activity
Hydrogen Ion Activity - Related Videos
14:22
Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation
0 Views •
Cited by 6 •
2014
Acoustic cavitation in liquids submitted to power ultrasound creates transient extreme conditions inside the collapsing bubbles, which are the origin of unusual chemical reactivity and light emission, known as sonoluminescence. In the presence of noble gases, nonequilibrium plasma is formed. The "hot" particles and the photons generated by collapsing bubbles are able to excite species in solution.
06:06
Hydrogenation
0 Views •
2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the hydrogenation of chalcone as an example of an alkene hydrogenation reaction (Figure 1). In this experiment, palladium on carbon (Pd/C) will be used as a heterogeneous catalyst for the process. A balloon will be used to supply the hydrogen atmosphere. Figure 1: Diagram showing the hydrogenation of chalcone to 3-phenylpropiophenone.
07:15
Amide Hydrogen/Deuterium Exchange & MALDI-TOF Mass Spectrometry Analysis of Pak2 Activation
0 Views •
Cited by 2 •
2011
MALDI-TOF mass spectrometry was successfully utilized to monitor the amide hydrogen/deuterium exchange in protein kinase Pak2 activation.
08:56
Catalytic Reactor: Hydrogenation of Ethylene
0 Views •
2023
Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA The hydrogenation of ethylene (C2H4) to ethane (C2H6) has often been studied as a model reduction reaction in characterizing new metal catalysts.1-2 While supported nickel is not the most active metal catalyst for this reaction, it is active enough that reaction can take place at < 200°C. The reaction typically involves adsorbed, dissociated hydrogen (H2) reacting...
03:24
Common Ion Effect
0 Views •
2020
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide: This solubility equilibrium may be shifted left by the addition of either silver(I) or iodide ions, resulting in...
FAQs
The activity coefficient, γH, adjusts the concentration term to reflect interactions between hydrogen ions, other ions, and solvent molecules. When those interactions become significant, the same numerical hydrogen-ion concentration can correspond to a different effective acidity than it would in an ideal solution. Using aH in pH calculations therefore connects chemical composition with the solution’s thermodynamic behavior.
Concentration-based acidity estimates are most vulnerable in concentrated or highly ionic solutions, because ion–ion and ion–solvent interactions alter effective behavior. In a dilute, relatively ideal solution, concentration may approximate the thermodynamic description more closely, but that approximation should not be assumed universally. Hydrogen ion activity becomes more informative when nonideality can affect predicted chemical behavior.
pH is calculated from hydrogen ion activity rather than inserted directly from [H+]: pH = −log10(aH). Because this relationship is logarithmic, changes in activity translate into corresponding pH changes, while changes in concentration alone do not necessarily predict the same result in a nonideal medium. This distinction matters when comparing acidity across solutions with different ionic environments.
In pH measurement, activity provides the basis for interpreting observed acidity thermodynamically rather than treating concentration as universally sufficient. This is especially important when a sample is concentrated or contains many ions, conditions under which nonideal behavior may be substantial. Reporting or calculating pH through aH can make measurements more reliable for chemical systems whose ionic composition varies.
Acid–base equilibrium calculations can use hydrogen ion activity to account for the solution environment in which an equilibrium occurs. Replacing a concentration-only description with the activity-based quantity helps distinguish changes caused by hydrogen-ion amount from changes caused by interactions in the medium. That distinction supports more accurate interpretation of equilibria in nonideal solutions.
In analytical chemistry, environmental studies, and formulation of chemical or biological systems, hydrogen ion activity helps maintain a consistent acidity framework across samples that may differ in ionic composition. It is useful when the practical question concerns how acidic a system behaves, not merely how much hydrogen-ion concentration is present. This supports reliable comparisons and calculations in chemically complex media.