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A '''reversible hydrogen electrode''' (RHE) is a [[reference electrode]], more specific a subtype of the [[standard hydrogen electrode]]s for [[electrochemical]] processes and differs from the standard hydrogen electrode by the fact that the measured [[potential]] does not change with the [[pH]] so that they can be directly used in the electrolyte.<ref>{{cite journal|doi=10.1021/jp037126d |title=The reversible hydrogen electrode: potential-dependent activation energies over platinum from quantum theory|year=2004|last1=Cai|first1=Yu|last2=Anderson|first2=Alfred B.|journal=The Journal of Physical Chemistry B|volume=108|issue=28|pages=9829}}</ref><ref>{{cite journal|author=Staehler, M.; Wipperman, K. and Stolten, D. |url=http://www.electrochem.org/dl/ma/206/pdfs/1863.pdf |title=Instabilities of the reversible hydrogen reference electrode in direct methanol fuel cells|journal=2004 Joint International Meeting of the Electrochemical Society, abstract 1863}}</ref><ref>{{cite journal|jstor=84265 |title=Hydrogen overvoltage|author=MacInnes, Duncan A. and Adler, Leon|pmc=1091559|pmid=16576366|year=1919|volume=5|issue=5|pages=160–3|journal=Proceedings of the National Academy of Sciences of the United States of America }}</ref> | |||
The name refers to the fact that the electrode is in the actual electrolyte solution and not separated by a salt bridge. The hydrogen ion concentration is therefore not 1, but corresponds to that of the electrolyte solution; in this way we can achieve a stable potential with a changing pH value. | |||
The potential of the RHE correlates to the pH value: | |||
:<math>E_0 = 0.000 - 0.059*pH</math> | |||
In general, for hydrogen electrodes in which the reaction: | |||
:<math> 2\; \mathrm{H_3 O^+} \; + \; 2\; \mathrm{e^-} \quad \overrightarrow{\leftarrow} \quad \mathrm{H_2} \; + \; 2\; \mathrm{H_2 O}</math> | |||
expires, the following dependence of the [[:wikt:equilibrium|equilibrium]] potential <math>E</math>, hydrogen pressure <math>p\mathrm{[H_2]}</math> and the activity of a <math>a\mathrm{[H_3 O^+]}</math> of the [[hydronium]] ions: | |||
:<math> E = E_{00} + \frac{R\;T}{F} \left( \ln \left( a[\mathrm{H_3 O^+}] \right) - \frac{1}{2}\ln\left( \;p[\mathrm{H_2}] \right) \right)</math> | |||
Here <math>E_{00}</math> is the standard reduction potential (this is by definition equal to zero), R is the [[universal gas constant]], T the [[absolute temperature]] and F is the [[Faraday constant]]. | |||
Surges occur in the [[electrolysis of water]] which means that the required [[cell voltage]] due to kinetic inhibition is higher than the equilibrium potential. The voltage increases with increasing current density at the electrodes. The measurement of equilibrium potentials is therefore possible without power. | |||
==Principle== | |||
The reversible hydrogen electrode is a fairly practical and reproducible electrode "standard." The term refers to a hydrogen electrode immersed in the electrolyte solution actually used. | |||
The benefit of that electrode is that no [[salt bridge]] is needed: | |||
* no contamination of the electrolyte by Cl<sup>-</sup> or SO<sub>4</sub><sup>2-</sup> | |||
* no diffusion potentials at the electrolyte bridge ([[liquid junction potential]]). This is important at temperature different to 25 °C. | |||
* long time measurements possible (no electrolyte bridge means no maintenance of the bridge) | |||
==See also== | |||
*[[Dynamic hydrogen electrode]] | |||
*[[Palladium-hydrogen electrode]] | |||
==References== | |||
{{reflist}} | |||
[[Category:Electrodes]] | |||
[[Category:Hydrogen technologies]] | |||
[[ja:基準電極#可逆水素電極]] | |||
Latest revision as of 07:55, 4 July 2013
A reversible hydrogen electrode (RHE) is a reference electrode, more specific a subtype of the standard hydrogen electrodes for electrochemical processes and differs from the standard hydrogen electrode by the fact that the measured potential does not change with the pH so that they can be directly used in the electrolyte.[1][2][3]
The name refers to the fact that the electrode is in the actual electrolyte solution and not separated by a salt bridge. The hydrogen ion concentration is therefore not 1, but corresponds to that of the electrolyte solution; in this way we can achieve a stable potential with a changing pH value. The potential of the RHE correlates to the pH value:
In general, for hydrogen electrodes in which the reaction:
expires, the following dependence of the equilibrium potential , hydrogen pressure and the activity of a of the hydronium ions:
![p{\mathrm {[H_{2}]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d2a7cdbb87796cae2198fb2bd285bbb3d3dee6ac)
![a{\mathrm {[H_{3}O^{+}]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/39ec7fd339c42c2a6d3028d9140ec02e32f60704)
![{\displaystyle E=E_{00}+{\frac {R\;T}{F}}\left(\ln \left(a[\mathrm {H_{3}O^{+}} ]\right)-{\frac {1}{2}}\ln \left(\;p[\mathrm {H_{2}} ]\right)\right)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/27609ee8b20dd4be8df19416763afcfd84bbd974)
Here is the standard reduction potential (this is by definition equal to zero), R is the universal gas constant, T the absolute temperature and F is the Faraday constant.
Surges occur in the electrolysis of water which means that the required cell voltage due to kinetic inhibition is higher than the equilibrium potential. The voltage increases with increasing current density at the electrodes. The measurement of equilibrium potentials is therefore possible without power.
Principle
The reversible hydrogen electrode is a fairly practical and reproducible electrode "standard." The term refers to a hydrogen electrode immersed in the electrolyte solution actually used.
The benefit of that electrode is that no salt bridge is needed:
- no contamination of the electrolyte by Cl- or SO42-
- no diffusion potentials at the electrolyte bridge (liquid junction potential). This is important at temperature different to 25 °C.
- long time measurements possible (no electrolyte bridge means no maintenance of the bridge)
See also
References
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In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang - ↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang