Mercury standard state

The Adsorption of Xenon on Mercury (Standard State r = 0.0608 dynes/cm.)... 

As the two amalgams have the same solvent (mercury), we may choose the same standard state for Pb in each amalgam. We choose a Henry s-law standard state because we have data for dilute amalgams and the solubility of Pb in Hg is limited. Equation (16.18) then will represent the Gibbs function change for Equation (17.19) ... 

This slide shows an example taken from an European standard for the analysis of mercury in water. For drinking water the standard states a reproducibility variation coefficient of 30% on a mercury concentration level of 0.8 pg/l. Provided that we can prove that we can perform as described in the standard our expanded measurement uncertainty (95% confidence) is estimated to 60%. 

Cassel and Neugebauer (18) investigated the adsorption of some of the rare gases on mercury over a range of temperatures by surface tension measurements. They found that the curves for surface pressure against gas pressure were almost linear and it is possible to interpolate their results to the standard state ir = 0.0608 dynes/cm., obtaining the pressure p0 in equilibrium with a film at this surface pressure. The thermodynamic quantities for the adsorption of xenon are given in Table IV ... 

Another example of this type is the adsorption of acetone on mercury (Kemball, 9) where the heat of adsorption to the same standard state is... 

About 80% of the elements are solid metals in their standard states at 298 K. Of the metallic elements, only mercury is a liquid at 298 K and at 1 atmosphere pressure (caesium melts at 302 K, gallium at 302.9 K). The non-metallic elements exist as either discrete small molecules, in the solid (S8), liquid (Br2) or gaseous (H2) states, or as extended atomic arrays in the solid state (C as graphite or diamond). The elements of Group 18 are monatomic gases at 298 K. 

The mercury atom is smaller than expected from the zinc-cadmium trend and is more difficult to ionize than the lighter atoms. In consequence the metal-metal bonding in mercury is relatively poor, resulting in the element being a liquid in its standard state. This almost Group 18 behaviour of mercury may be compared to that of a real Group 18 element, xenon, which has first and second ionization energies of 1170 and 2050 kJ mol. ... 

Armbruster and Crenshaw, J. Am. Chem. Soc., 56, 2525 (1934)]. Determine the activity and activity coefficient of the potassium in each of these amalgams at 25 C. Utilize the result of the preceding exercise to determine the same quantities for the solvent (mercury). Indicate the standard state employed in each case. 

The thermodynamic standard state of a substance is its most stable pure form under standard pressure (one atmosphere) and at some specific temperature (25°C or 298 K unless otherwise specified). Examples of elements in their standard states at 25°C are hydrogen, gaseous diatomic molecules, H2(g) mercury, a silver-colored liquid metal,... 

Calculate E° for the reactions of mercury with (a) 1 M HCl and (b) 1 M HNO3. Which acid will oxidize Hg to Hg under standard-state conditions Can you identify which test tube below contains HNO3 and Hg and which contains HCl and Hg ... 

The same is true for pure liquids (undissolved) in equilibrium, such as mercury. The standard state of water is taken as unity in dilute aqueous solutions, and water does not appear in equilibrium constant expressions. 

The standard state of an element is the form in which the element exists under conditions of 1 atmosphere and 25°C. (The standard state for oxygen is 02(5) at a pressure of 1 atmosphere the standard state for sodium is Na(s) the standard state for mercury is Hg(/) and so on.)... 

Hess s law allows you to calculate unknown AH values using known reactions and their experimentally determined AH values. However, recording AH values for all known chemical reactions would be a huge and unending task. Instead, scientists record and use enthalpy changes for only one type of reaction—a reaction in which a compound is formed from its elements in their standard states. The standard state of a substance means the normal physical state of the substance at 1 atm and 298 K (25°C3. For example, in their standard states, iron is a solid, mercury is a liquid, and oxygen is a diatomic gas. 

We omit the subscript cell because this reaction is not carried out in an electrochemical cell.) Since E° is negative, we conclude that mercury is not oxidized by hydrochloric acid under standard-state conditions. 

The decrease in free energy of the system in a spontaneous redox reaction is equal to the electrical work done by the system on the surroundings, or AG = nFE. The equilibrium constant for a redox reaction can be found from the standard electromotive force of a cell. 10. The Nernst equation gives the relationship between the cell emf and the concentrations of the reactants and products under non-standard-state conditions. Batteries, which consist of one or more galvanic cells, are used widely as self-contained power sources. Some of the better-known batteries are the dry cell, such as the Leclanche cell, the mercury battery, and the lead storage battery used in automobiles. Fuel cells produce electrical energy from a continuous supply of reactants. 

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