Triple Point » Constants and Units http://pontotriplo.org/triplepoint A selection of posts from Ponto Triplo - a Portuguese blog with links to the best chemistry sites, news and events Sun, 19 Apr 2009 23:15:30 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Convert Plus http://pontotriplo.org/triplepoint/2005/12/convert_plus.html http://pontotriplo.org/triplepoint/2005/12/convert_plus.html#comments Tue, 06 Dec 2005 19:40:15 +0000 Jorge Goncalves http://pontotriplo.org/triplepoint/?p=135 ]]> Just arrived in my Inbox: Convert Plus – Online Units Conversion. My first impression is that it seems to be a very interesting online converter. It is very comprehensive and has the benefit of converting some units and measures to somewhat exotic units systems, which is not usually found in this kind of converters.

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]]> http://pontotriplo.org/triplepoint/2005/12/convert_plus.html/feed 1 Attograms, Zeptograms and Yoctograms http://pontotriplo.org/triplepoint/2005/04/attograms_zepto.html http://pontotriplo.org/triplepoint/2005/04/attograms_zepto.html#comments Mon, 04 Apr 2005 00:37:00 +0000 Jorge Goncalves http://pontotriplo.org/triplepoint/?p=112 ]]> The measurement of the mass of a protein molecule, on the zeptogram (10-21 g) scale, is now possible, as can be read on New Scientist.com. Previously, in 2000, the mass of a cluster of gold atoms, near one attogram (10-18 g) was already measured. The next goal, a gigantic step, is to develop devices capable of weighing masses on the yoctogram (10-24 g) scale, meaning measuring the mass of a single hydrogen atom. The article is worth reading as is this one, published on PhysOrg.

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]]> http://pontotriplo.org/triplepoint/2005/04/attograms_zepto.html/feed 0 WWW Unit Converter http://pontotriplo.org/triplepoint/2005/04/www_unit_conver.html http://pontotriplo.org/triplepoint/2005/04/www_unit_conver.html#comments Mon, 04 Apr 2005 00:21:00 +0000 Jorge Goncalves http://pontotriplo.org/triplepoint/?p=111 ]]> One of the best and most complete online units’ converters: WWW Unit Converter.

Update: An extensive list of online converters and calculators can be found on Martindale’s Reference Desk: Units Conversion, Chemistry Calculators and Calculators for different fields and activities.

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]]> http://pontotriplo.org/triplepoint/2005/04/www_unit_conver.html/feed 2 A kilogram is a kilogram. Well, may be not… http://pontotriplo.org/triplepoint/2005/03/a_kilogram_is_a.html http://pontotriplo.org/triplepoint/2005/03/a_kilogram_is_a.html#comments Tue, 29 Mar 2005 16:05:39 +0000 Jorge Goncalves http://pontotriplo.org/triplepoint/?p=106 ]]> According to the article New look for the kilogram, published on PhysicsWeb, researchers from University of Reading and NIST have proposed new methods to define kilogram, based on fundamental constants. The kilogram, one of the seven International System of Units (SI) base units (the only which is still defined by a material artefact) is defined as the mass of the international prototype of the kilogram kept at the Bureau International des Poids et Mesures (BIPM). This prototype is a cylinder made of an alloy for which the mass fraction of platinum is 90 % and the mass fraction of iridium is 10 %. The problem is the mass of the international prototype increases by approximately 1 part in 109 per year, due to the inevitable accumulation of contaminants on its surface. In this context, scientists have proposed two ways to redefine the unit of mass. The first is based on the Planck constant and requires a 1-kilogram mass to be supported against Earth’s gravity using a precisely measured magnetic force. The second technique is based on the Avogadro constant, and involves counting a certain number of atoms of a specific atomic mass. Nevertheless, none of these definitions will be adopted before 2007. Until then we can continue to trust our balances measurements…

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]]> http://pontotriplo.org/triplepoint/2005/03/a_kilogram_is_a.html/feed 0 Roentgenium http://pontotriplo.org/triplepoint/2005/02/roentgenium_1.html http://pontotriplo.org/triplepoint/2005/02/roentgenium_1.html#comments Wed, 02 Feb 2005 23:59:00 +0000 Jorge Goncalves http://pontotriplo.org/triplepoint/?p=86 ]]> IUPAC Recommendation about the name and symbol of the element with atomic number 111. The recommended name is Roentgenium with symbol Rg. (see report in pdf format)

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]]> http://pontotriplo.org/triplepoint/2005/02/roentgenium_1.html/feed 0 New Best Estimates of the Values of the Fundamental Constants http://pontotriplo.org/triplepoint/2005/01/new_best_estima_1.html http://pontotriplo.org/triplepoint/2005/01/new_best_estima_1.html#comments Sat, 22 Jan 2005 02:07:00 +0000 Jorge Goncalves http://pontotriplo.org/triplepoint/?p=73 ]]> New Best Estimates of the Values of the Fundamental Constants is an interesting article by Ian Mills, published in the IUPAC magazine (May-June 2004), Chemistry International. The best estimates for these values can be found in this table (PDF), or then in Fundamental Physical Constants, part of the excellent NIST Reference on Constants, Units, and Uncertainty.

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