Problem
A radio station announcer reports the atmospheric pressure to be 99.6 kPa. What is the pressure in atmospheres? In millimeters of mercury?
Solution
Look up conversions factors in a table to convert between kilopascals and atmospheres and millimeters of mercury. Use a conversion factor approach to solve the problem:
99.6 kPa x 1 atm/101.3 kPa = 0.983 atm
0.983 atm x 760 mm Hg/1 atm = 747 mm Hg
Answer
0.983 atm; 747 mm Hg
Yasiel Hernandez
Wednesday
World's smallest pipette
Smallest pipette delivers zeptolitre volumes16 April 2007
The world's smallest pipette has been developed by US scientists. It is capable of dispensing drops of a molten gold-germanium alloy with a volume of a few zeptolitres, that is, a billionth of a trillionth of a litre. Watching these tiny drops led Eli and Peter Sutter of the Brookhaven National Laboratory, New York to make observations that challenge the classical theory of crystallisation. Their findings are published in the journal Nature Materials this week.1
Close up on world's smallest pipette
© Nature
To create the nanopipette the authors used a gold catalyst to grow a germanium nanotube with a tip containing a reservoir of molten Au-Ge alloy. The whole thing was encapsulated within sheets of graphene which was pierced at the tip with an electron beam allowing the melt to flow out.
When Eli Sutter explains that these drops are 'quite small', it's something of an understatement. The previous record was an attolitre pipette, producing volumes around 100 times larger.2 Now, drops containing only a few thousand atoms have been dispensed, and their size means they behave differently to bulk liquids when cooled to just above their melting point. They are too large, however for computer simulation which becomes too complicated above a few hundred atoms.
Conventional crystallisation theory states that crystals nucleate around an impurity somewhere in the bulk and grow outward from that point. But the pipette produces droplets so pure that this could be ruled out, meaning Sutter didn't know what to expect watching the drops cool with a transmission electron microscope.
Dancing droplet
© Nature
In fact, just above the melting point she saw the drop start to develop thin solid-like flat facets at the surface. These facets would disappear and re-appear elsewhere on the surface 'a little bit like a dance', said Sutter. A couple more degrees cooler and the facets became frozen in as the drop solidified from the outside in.
The drops were studied while suspended from the pipette tip by a 10 Å thread of alloy. This removes any interactions between a container and the drop surface that could hide such subtle effects. The drop is 'practically levitating' said Sutter, who also hinted that 'quasi-free' drops like these might shed light on how atmospheric droplets behave, with implications for modelling climate behaviour. Sutter cautions that the conditions in these experiments would be make it impossible to repeat them with water, however.
Andreas Bruckbauer of the Department of Chemistry, University of Cambridge said this was 'a truly amazing method' of dispensing liquids, for a specialized but 'very interesting and very important' purpose.
Harry Heinzelmann of the Centre Suisse d'Electronique et de Microtechnique in Switzerland developed the previous smallest pipette, and is similarly impressed. The new method is limited by the material being dispensed, but 'allows scientific work that was not possible before' and complements existing techniques, he said. Sutter now plans to repeat the experiments using alloys with different surface energies, and hopes this could lead to improved control of drop growth to atomic resolution.
Yasiel Hernandez
The world's smallest pipette has been developed by US scientists. It is capable of dispensing drops of a molten gold-germanium alloy with a volume of a few zeptolitres, that is, a billionth of a trillionth of a litre. Watching these tiny drops led Eli and Peter Sutter of the Brookhaven National Laboratory, New York to make observations that challenge the classical theory of crystallisation. Their findings are published in the journal Nature Materials this week.1
Close up on world's smallest pipette
© Nature
To create the nanopipette the authors used a gold catalyst to grow a germanium nanotube with a tip containing a reservoir of molten Au-Ge alloy. The whole thing was encapsulated within sheets of graphene which was pierced at the tip with an electron beam allowing the melt to flow out.
When Eli Sutter explains that these drops are 'quite small', it's something of an understatement. The previous record was an attolitre pipette, producing volumes around 100 times larger.2 Now, drops containing only a few thousand atoms have been dispensed, and their size means they behave differently to bulk liquids when cooled to just above their melting point. They are too large, however for computer simulation which becomes too complicated above a few hundred atoms.
Conventional crystallisation theory states that crystals nucleate around an impurity somewhere in the bulk and grow outward from that point. But the pipette produces droplets so pure that this could be ruled out, meaning Sutter didn't know what to expect watching the drops cool with a transmission electron microscope.
Dancing droplet
© Nature
In fact, just above the melting point she saw the drop start to develop thin solid-like flat facets at the surface. These facets would disappear and re-appear elsewhere on the surface 'a little bit like a dance', said Sutter. A couple more degrees cooler and the facets became frozen in as the drop solidified from the outside in.
The drops were studied while suspended from the pipette tip by a 10 Å thread of alloy. This removes any interactions between a container and the drop surface that could hide such subtle effects. The drop is 'practically levitating' said Sutter, who also hinted that 'quasi-free' drops like these might shed light on how atmospheric droplets behave, with implications for modelling climate behaviour. Sutter cautions that the conditions in these experiments would be make it impossible to repeat them with water, however.
Andreas Bruckbauer of the Department of Chemistry, University of Cambridge said this was 'a truly amazing method' of dispensing liquids, for a specialized but 'very interesting and very important' purpose.
Harry Heinzelmann of the Centre Suisse d'Electronique et de Microtechnique in Switzerland developed the previous smallest pipette, and is similarly impressed. The new method is limited by the material being dispensed, but 'allows scientific work that was not possible before' and complements existing techniques, he said. Sutter now plans to repeat the experiments using alloys with different surface energies, and hopes this could lead to improved control of drop growth to atomic resolution.
Yasiel Hernandez
Bioethanol fuel
Bioethanol fuel 'as big a health risk as gasoline'18 April 2007
The use of ethanol as a gasoline substitute for motor vehicles may not be the environmental panacea that its proponents would have us believe, according to a US atmospheric scientist.
Bioethanol - ethanol derived from the fermentation of crops such as maize or sugar - is becoming increasingly available as a 'green' and sustainable alternative to gasoline. It is often sold at the fuel pumps as E85 - an 85:15 mixture of ethanol and gasoline.
How 'green' is green?Now, however, Mark Jacobson of Stanford University is calling into question the environmental credentials of fuels consisting mainly of bioethanol. Jacobson ran computer models of the impacts on atmospheric pollution and human health of vehicles running exclusively on an ethanol mixture and concluded that the number of respiratory-related deaths and illness would increase.
'Our results show that a high blend of ethanol poses an equal or greater risk to public health than gasoline,' Jacobson said.
He ran a series of simulations of atmospheric conditions around Los Angeles in the year 2020 comparing two scenarios: all vehicles running on gasoline versus all vehicles running on E85.
'We found that E85 vehicles reduce atmospheric levels of two carcinogens, benzene and butadiene, but increase two others - formaldehyde and acetaldehyde,' Jacobson said. 'As a result, cancer rates for E85 are likely to be similar to those for gasoline. However, in some parts of the country, E85 significantly increased ozone, a prime ingredient of smog.' The increased ozone, Jacobson suggested, would result in more asthma-related admissions to hospitals.
'There are alternatives, such as battery-electric, plug-in-hybrid and hydrogen-fuel cell vehicles, whose energy can be derived from wind or solar power,' Jacobson said. 'It would seem prudent, therefore, to address climate, health and energy with technologies that have known benefits.'
The Ford motor company, which produces 'Flexi-Fuel' cars that can run on both E85 and gasoline, was unimpressed by Jacobson's findings.
'The phasing in of E85 is in the interest of developing energy alternatives to petroleum and to encourage the use of renewable fuel to help with CO2 reduction for climate change,' a spokesman told Chemistry World. 'Local emission regulations, such as hydrocarbons, aldehydes or subsequent ozone, are not the compelling reason to pursue E85.'
In any event, the spokesman said, Ford's flexible fuel vehicles using E85 'must comply with the regulated emissions of HC, CO, NOx, formaldehyde, and particulate, as with any vehicle. Air quality regions, such as southern California, must be satisfied that the test results of these vehicles are acceptable for local air quality requirements. Vehicles that do not comply will not be sold.' He added that the baseline data used by Jacobson, from 2002, 'is not likely to be very representative of 2020 vehicles, particularly in ozone-constrained regions such as southern California where requirements are stringent, so care is needed in interpreting data this far into the future while technology continues to evolve. 'Unburned ethanol and associated acetaldehyde are concerns with E85 due to lower exhaust temperatures, making high catalyst efficiency more difficult, but we also think this issue can be resolved by the time E85 will be prevalent.'
Yasiel Hernandez
The use of ethanol as a gasoline substitute for motor vehicles may not be the environmental panacea that its proponents would have us believe, according to a US atmospheric scientist.
Bioethanol - ethanol derived from the fermentation of crops such as maize or sugar - is becoming increasingly available as a 'green' and sustainable alternative to gasoline. It is often sold at the fuel pumps as E85 - an 85:15 mixture of ethanol and gasoline.
How 'green' is green?Now, however, Mark Jacobson of Stanford University is calling into question the environmental credentials of fuels consisting mainly of bioethanol. Jacobson ran computer models of the impacts on atmospheric pollution and human health of vehicles running exclusively on an ethanol mixture and concluded that the number of respiratory-related deaths and illness would increase.
'Our results show that a high blend of ethanol poses an equal or greater risk to public health than gasoline,' Jacobson said.
He ran a series of simulations of atmospheric conditions around Los Angeles in the year 2020 comparing two scenarios: all vehicles running on gasoline versus all vehicles running on E85.
'We found that E85 vehicles reduce atmospheric levels of two carcinogens, benzene and butadiene, but increase two others - formaldehyde and acetaldehyde,' Jacobson said. 'As a result, cancer rates for E85 are likely to be similar to those for gasoline. However, in some parts of the country, E85 significantly increased ozone, a prime ingredient of smog.' The increased ozone, Jacobson suggested, would result in more asthma-related admissions to hospitals.
'There are alternatives, such as battery-electric, plug-in-hybrid and hydrogen-fuel cell vehicles, whose energy can be derived from wind or solar power,' Jacobson said. 'It would seem prudent, therefore, to address climate, health and energy with technologies that have known benefits.'
The Ford motor company, which produces 'Flexi-Fuel' cars that can run on both E85 and gasoline, was unimpressed by Jacobson's findings.
'The phasing in of E85 is in the interest of developing energy alternatives to petroleum and to encourage the use of renewable fuel to help with CO2 reduction for climate change,' a spokesman told Chemistry World. 'Local emission regulations, such as hydrocarbons, aldehydes or subsequent ozone, are not the compelling reason to pursue E85.'
In any event, the spokesman said, Ford's flexible fuel vehicles using E85 'must comply with the regulated emissions of HC, CO, NOx, formaldehyde, and particulate, as with any vehicle. Air quality regions, such as southern California, must be satisfied that the test results of these vehicles are acceptable for local air quality requirements. Vehicles that do not comply will not be sold.' He added that the baseline data used by Jacobson, from 2002, 'is not likely to be very representative of 2020 vehicles, particularly in ozone-constrained regions such as southern California where requirements are stringent, so care is needed in interpreting data this far into the future while technology continues to evolve. 'Unburned ethanol and associated acetaldehyde are concerns with E85 due to lower exhaust temperatures, making high catalyst efficiency more difficult, but we also think this issue can be resolved by the time E85 will be prevalent.'
Yasiel Hernandez
Making pH Paper Test Strips
Make pH Paper Test Strips
This is an example of a project that doesn't require a lab or special chemicals and that is safe and easy enough for kids to do. You can make your own pH paper using nothing more complicated than a cabbage and coffee filters. My instructions involve using a blender and a microwave, but you can just as easily chop the cabbage, steep it like a tea in a small amount of boiling water, and make pH paper from the juice. You say you don't have cabbage? That's okay, too. There are many other common plants that you can substitute. The reason cabbage is most often used is because it exhibits a wide color change range.
pH
2
4
6
8
10
12
Color
Red
Purple
Violet
Blue
Blue-Green
Greenish Yellow
Yasiel Hernandez
This is an example of a project that doesn't require a lab or special chemicals and that is safe and easy enough for kids to do. You can make your own pH paper using nothing more complicated than a cabbage and coffee filters. My instructions involve using a blender and a microwave, but you can just as easily chop the cabbage, steep it like a tea in a small amount of boiling water, and make pH paper from the juice. You say you don't have cabbage? That's okay, too. There are many other common plants that you can substitute. The reason cabbage is most often used is because it exhibits a wide color change range.
pH
2
4
6
8
10
12
Color
Red
Purple
Violet
Blue
Blue-Green
Greenish Yellow
Yasiel Hernandez
Friday
Have You Selected Wrong Materials for Chemicals?
this article i found it pretty interesting because Chemicals are very much a part of our lifestyles. Every household detergent, solvent, and bleach that you use in your homes is a result of some production efforts from manufacturing plants somewhere in the world around you. Fertilizer, automobile radiator coolant, shampoo, soap, insecticide, paint solvent, lubricants, fuel oil are just a few that I can name right now. I’m sure you can find more around you, but you get the point. We use chemicals everywhere. One of the main jobs for Plant Engineers is to maintain the numerous pumps installed at their plant. These pumps can count into the hundreds or even thousands, depending on the size of the plant. So you should realize that to do a proper preventive maintenance, it is no mean task. There must be regular schedules, proper tracking of jobs done, available manpower and skills, suitable tools, replacement parts, materials and a proper system of administration of all these.
Sometimes, even with all the maintenance activities being carried out, pumps do fail. And when they do, plant engineers will have to find out what causes them to fail. Especially with new pumps where there is very little record trend of breakdown, engineers will be hard pressed into finding solutions for this. This is when experience helps in pinpointing the causes of the failure. Engineers in such chemical processing plants need to know what materials are suitable to be used for their process. It is much more complex than just selecting materials for water pumps. Much detailed and careful selection choices based on the chemicals, the temperatures (because some of the plastic materials can weaken at temperatures that are considered normal for metals), chemical reactions, safety, spills and many others have to be taken.
With so many chemicals in use today, how do we know what materials can be used for what chemicals? Sometimes liquids to be pumped contain chemicals that are both corrosive and abrasive. Should we choose a plastic or a metal housing? Sometimes chemicals may become hot either through the process or through mis-operation of the system - perhaps, somebody forgot to open a valve. Plastic parts can weaken at high temperatures.
Rodrigo Monsalve
http://www.buzzle.com/articles/wrong-materials-chemicals.html
Sometimes, even with all the maintenance activities being carried out, pumps do fail. And when they do, plant engineers will have to find out what causes them to fail. Especially with new pumps where there is very little record trend of breakdown, engineers will be hard pressed into finding solutions for this. This is when experience helps in pinpointing the causes of the failure. Engineers in such chemical processing plants need to know what materials are suitable to be used for their process. It is much more complex than just selecting materials for water pumps. Much detailed and careful selection choices based on the chemicals, the temperatures (because some of the plastic materials can weaken at temperatures that are considered normal for metals), chemical reactions, safety, spills and many others have to be taken.
With so many chemicals in use today, how do we know what materials can be used for what chemicals? Sometimes liquids to be pumped contain chemicals that are both corrosive and abrasive. Should we choose a plastic or a metal housing? Sometimes chemicals may become hot either through the process or through mis-operation of the system - perhaps, somebody forgot to open a valve. Plastic parts can weaken at high temperatures.
Rodrigo Monsalve
http://www.buzzle.com/articles/wrong-materials-chemicals.html
Green Sand!!!
Have you heard about any beach that has green sand??
This article that I foudn describes that this beach sand may be the only one in the world!!
The sand consists of spheres of olivine, or peridot. Each grain is a clear olive green. White sand primarily is quartz, which is an uncolored silicate (SiO2), and other light-colored minerals (white sand beaches in Hawaii, on the other hand, are almost entirely made from smoothed shells, or calcium carbonate, rather than inorganic minerals). Olivine is another silicate, though with magnesium and iron in its crystal matrix. The metals are responsible for the characteristic color.
As the author of the article shares her experience "You're not supposed to disturb sand at pretty much any beach in Hawaii, but I figure if you can walk on it, you can pick it up and photograph it. It's a deep layer of green, not just a sprinkling of green on top of regular sand. This beach is well worth the drive or hike to see firsthand"
Hopefully we could get to visit in ina near future!!!
Take care!! all you!!
NOHORA DUQUE
Plastic modified to meet electronic needs
A U.S. scientist has modified a plastic so its ability to conduct electricity can be altered during manufacturing to meet future electronic device needs. Yueh-Lin Loo, an assistant professor of chemical engineering at The University of Texas at Austin, conducted her research with a plastic called polyaniline, which could serve as flexible, inexpensive wiring in future products such as military camouflage that changes colors, foldable electronic displays and medical sensors.
By combining polyaniline with a chemical that gives it conductivity, Loo discovered she could increase the plastic's conductivity one- to six-fold based on the version of the chemical added.
The results of her research involving the chemical polymer acid appear in the April 7 issue of the Journal of Materials Chemistry.
Copyright 2007 by United Press International. All Rights Reserved.
Further Information: http://www.sciencedaily.com/
Posted: Vivian Coolen
By combining polyaniline with a chemical that gives it conductivity, Loo discovered she could increase the plastic's conductivity one- to six-fold based on the version of the chemical added.
The results of her research involving the chemical polymer acid appear in the April 7 issue of the Journal of Materials Chemistry.
Copyright 2007 by United Press International. All Rights Reserved.
Further Information: http://www.sciencedaily.com/
Posted: Vivian Coolen
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