RIM's first all-screen Curve has sashayed over to the FCC. Two models of the BlackBerry Curve 9380, the REA70UW and REB70UW, are included in the latest filing, which goes into typical laborious detail on radio frequencies and the like. Thankfully, those myriad charts and graphs reveal support for WCDMA band IV, meaning that the phone plays nice with T-Mobile's 3G network. Let's just hope that, if given the chance to strut its stuff in the US market, it follows the Curve family tradition of arriving keenly priced. We'll have to wait and see if it hits our wallet's sweet spot, but for those more interested in the phone's internals, the source link beckons below.
Source from:
http://www.engadget.com/2011/11/24/blackberry-curve-9380-hits-the-fcc-talking-the-t-mobile-talk/
Hydraulic fracturing, notorious for its environmental hazards all this while, has now come under the scanner for its alleged connection with increased seismic activity. Continue reading to see how fracking - that this practice is popularly known as, can trigger earthquakes, and how damaging these quakes can be.The 5.6 magnitude earthquake that rocked the state of Oklahoma on 5th November, 2011, has once again raised some serious questions about the increasing use of hydraulic fracturing to tap natural resources, i.e. oil and gas, from beneath the Earth's crust. Even though it has not yet been ascertained whether this quake was caused as a result of weakening of the Earth's crust as a result of fracking, most of the people believe so. The experts at the United States Geological Survey (USGS) though, are of the opinion that fracking cannot trigger an earthquake of this magnitude. According to them, it was the fault line existing in this region that triggered the Oklahoma earthquake - and not fracking.
Link Between Hydraulic Fracturing and Earthquakes
While the presence of a fault line in this region of the United States can be an apt explanation for the 5.6 magnitude Oklahoma earthquake, what about the sudden rise in seismic activity here? Between 1972 to 2008, an average of 2-6 earthquakes were recorded in the state of Oklahoma every year. In 2009, the number of earthquakes recorded reached 50, and further increased to a whopping 1047 in 2010. One cannot ignore the fact that more than a thousand drilling wells and more than a hundred injection wells have cropped up in this region over the course of time. Back in August itself, the region experienced a series of tremors, all ranging between the magnitude of 1 and 2.5, and now the 5.6 magnitude quake. While environmentalists are citing the link between hydraulic fracturing and earthquakes to oppose such projects, those in this business refute these allegations as baseless.
Man-made Hydraulic Fracturing
Hydraulic fracturing is basically the process wherein a fluid - which is basically a mixture of water and some chemicals, is pumped underground at high pressure to develop cracks in the sediment layers which have the natural gas and oil trapped within. While breakdown of sediment layers due to the development of veins and dikes does occur, it is not as rampant as man-made hydraulic fracturing - a technology used to harness natural oil and gas trapped within the Earth's crust. Man-made hydraulic fracturing is more often referred to as 'fracking' or 'hydrofracking'. While many people tend to associate fracking with drilling, the fact is that the two are totally different concepts, and fracking is used only after the process of drilling is complete.
Even though there is abundance of natural gas and oil in shale, its characteristic low permeability can hamper the flow of these natural resources. In such circumstances, one convenient method of releasing these trapped resources is to make cracks in the rock bed - and this is exactly what is done in the process of hydraulic fracturing. After vertical drilling is complete, horizontal drilling is done in the targeted sediment layer, i.e. the hydrofrac zone or hydraulic fracturing zone, to make passage for the 'fracfluid'. When the fracfluid is released at high pressure, it causes the targeted layer to crack, and the gas which is released as a result of this makes its way to the surface through the bore-well. At times, hydraulic fracturing is also used to restore the cracks within the formation to ensure unabated flow of natural oil and gas in the existing wells.
Does Hydraulic Fracturing Trigger Earthquakes?
Until recently, hydraulic fracturing was opposed for its tendency to pollute ground water, but the series of earthquakes in the United States and the United Kingdom has once again brought it to the headlines. This time it is the sudden rise in seismic activity in Oklahoma and surrounding regions, followed by the 5.6 magnitude earthquake, that has brought the alleged link between fracking and earthquakes to the forefront. Environmentalists argue that the sudden rise in seismic activity and the rise in the number of injection wells in this region cannot be a coincidence, and there has to be some link between the two.
If the experts at the USGS are to be believed, it is not possible for such intense earthquakes to be caused as a result of human activities such as fracking. These experts further add that such intense earthquakes are usually attributed to plate tectonics. However, they don't deny the chances of human activities causing minor earthquakes. In fact, deep injection of fluid and nuclear detonations are the two prominent human activities with the ability to trigger tremors by the USGS. That being said, they do make it a point to add that the earthquakes caused as a result of these activities are not of such high magnitude.
Previously there have been cases of earthquakes being triggered by deep injection of wastewater and deep injection of water for the production of geothermal power. One prominent example is that of the Rocky Mountain Arsenal (RMA) deep injection well which was built by the RMA in 1961 for disposing liquid waste, but only used till 1966 as it was eventually revealed that the fluid injection was triggering earthquakes in this area. As the regions with abundance of natural oil and gas are usually located along the fault lines, it gives rise to the misconception that energy exploration and production makes us vulnerable to hazards such as earthquakes.
While that does rule out the chances of major earthquakes, like the one in Oklahoma, being triggered by hydraulic fracturing, it also suggests that less-intense seismic activity can be linked to the practice of harnessing natural gas and oil. However, one also has to note that major earthquakes can be triggered as a result of fluid injection when it is injected at the wrong place - an unknown fault for instance. In such circumstances, earthquakes with a magnitude of 5 or more cannot be ruled out.
NEW YORK (AP) — Lululemon Athletica Inc. named Facebook executive Emily White to its board, saying her social media and e-commerce experience complements the yoga-wear retailer's online efforts.
The Canadian company said Friday that White's addition expanded the board to 10 members.
White is senior director of local and mobile partnerships at Facebook, which she joined in 2010. Before that, she served in several e-commerce positions at Google from 2001 to 2010.
"Emily brings a wealth of knowledge regarding e-commerce and social media to our board in a time when our customers are utilizing these communication channels more than ever to both shop and enrich their lives," Lululemon Chairman Chip Wilson said.
Lululemon offers shopping on its site as well as videos and a blog about yoga, running and other topics.
It's been one of the hottest chains in retailing. The popularity of its high-priced yoga pants and tank tops — the pants run about $100 — has helped shares more than double in the past 12 months.
Shares rose $1.22, or 2.4 percent, to $51.54 in premarket trading.
Read More:
http://news.yahoo.com/lululemon-names-facebook-exec-emily-white-board-141303226.html
The Canadian company said Friday that White's addition expanded the board to 10 members.
White is senior director of local and mobile partnerships at Facebook, which she joined in 2010. Before that, she served in several e-commerce positions at Google from 2001 to 2010.
"Emily brings a wealth of knowledge regarding e-commerce and social media to our board in a time when our customers are utilizing these communication channels more than ever to both shop and enrich their lives," Lululemon Chairman Chip Wilson said.
Lululemon offers shopping on its site as well as videos and a blog about yoga, running and other topics.
It's been one of the hottest chains in retailing. The popularity of its high-priced yoga pants and tank tops — the pants run about $100 — has helped shares more than double in the past 12 months.
Shares rose $1.22, or 2.4 percent, to $51.54 in premarket trading.
Read More:
http://news.yahoo.com/lululemon-names-facebook-exec-emily-white-board-141303226.html
Enzymes are essential for almost all the chemical reactions that take place inside living cells. However, the activities of the enzymes can be enhanced or inhibited by a number of factors. In this article, we are talking about all those factors that affect enzyme activity.
Enzymes are protein-based complex molecules produced by the cells. There are several enzymes which are involved with different biochemical reactions. Each of these enzymes present in our body can influence any one particular chemical reaction or a set of reactions. They serve as organic catalysts and enhance the speed of the reactions in which they take part. In the absence of an enzyme, the speed of a chemical reaction becomes extremely slow. Some of these reactions may not occur if the right kind of enzyme is not present in the body.
Enzyme Activity Explained
An enzyme can increase the speed of a chemical reaction manifold. You will be surprised to know that studies have found that it can make a chemical reaction 10 billion times faster. The chemical substances that are present at the start of a biochemical process is termed as substrates which undergo chemical change(s) to form one or more end products. Basically, the active site of the enzymes forms a temporary bond with the substrate. During this time, an enzyme lowers the activation energy of the participant molecules which in turn speeds up the reaction. After the reaction is over, the newly formed product leaves the surface of the enzyme and the enzyme gets back its original shape. Thus, you can say it participates in the reaction without undergoing any physical or chemical change. Therefore, the same enzyme is used again and again for the specific process.
Factors Influencing Enzyme Activity
Concentrations of substrate and enzyme have an impact on the activity of the enzymes. Besides, environmental conditions such as temperature, pH values, presence of inhibitors, etc. also influence their activities. Each of these important factors have been discussed below:
Effects of Change in Temperature
All enzymes need a favorable temperature to work properly. The rate of a biochemical reaction increases with rise in temperature. This is because the heat enhances the kinetic energy of the participant molecules which results in more number of collisions between them. On the other hand, it is mostly found that in low temperature conditions, the reaction becomes slow as there is less contact between the substrate and the enzyme. However, extreme temperatures are not good for the enzymes. Under the influence of very high temperature, the enzyme molecule tends to get distorted, due to which the rate of reaction decreases. In other words, a denatured enzyme fails to carry out its normal functions. In the human body, the optimum temperature at which most enzymes become highly active lies in the range of 95 °F to 104 °F (35 °C to 40 °C). There are some enzymes that prefer a lower temperature than this.
Effects of Change in pH Value
The efficiency of an enzyme is largely influenced by the pH value of its surroundings. This is because the charge of its component amino acids changes with the change in the pH value. Each enzyme becomes active at a certain pH level. In general, most enzymes remain stable and work well in the pH range of 6 and 8. However, there are some specific enzymes which work well only in acidic or basic surroundings. The favorable pH value for a specific enzyme actually depends on the biological system in which it is working. When the pH value becomes very high or too low, then the basic structure of the enzyme undergoes change(s). As a result, the active site of the enzyme fails to bind well with the substrate properly and the activity of the enzyme gets badly affected. The enzyme may even stop functioning completely.
Effects of Substrate Concentration
Substrate concentration plays a major role in various enzyme activities. This is obviously because higher concentration of substrate means more number of substrate molecules are involved with the enzyme activity. Whereas, a low concentration of substrate means less number of molecules will get attached to the enzymes. This in turn reduces the enzyme activity. When the rate of an enzymatic reaction is maximum and the enzyme is at its most active state, an increase in the concentration of substrate will not make any difference in the enzyme activity. In this condition, the substrate is continuously replaced by new ones at the active site of the enzyme and there is no scope to add those extra molecules there.
Effects of Enzyme Concentration
In any enzymatic reaction, the quantity of substrate molecules involved is more as compared to the number of enzymes. A rise in enzyme concentration will enhance the enzymatic activity for the simple reason that more enzymes are participating in the reaction. The rate of the reaction is directly proportional to the quantity of enzymes available for it. However, that does not mean that a constant rise in concentration of enzymes will lead to a steady rise in the rate of reaction. Rather, a very high concentration of enzymes where all the substrate molecules are already used up does not have any impact on the reaction rate. To be precise, once the rate of reaction has attained stability, an increase in the quantity of enzymes does not affect the rate of reaction anymore.
Effects of Inhibitors
As the name suggests, inhibitors are those substances that have a tendency to prevent activities of the enzymes. Enzyme inhibitors interfere with the enzyme functions in two different ways. Based on this, they are divided into two categories: competitive inhibitors and noncompetitive inhibitors. A competitive inhibitor has a structure which is the same as that of a substrate molecule, and so it gets attached to the activated center of the enzyme easily and restricts the bond formation of enzyme-substrate complex. A noncompetitive inhibitor is the one which brings about change(s) in the shape of the enzymes by reacting with its active site. In this condition, the substrate molecule cannot bind itself to the enzyme and thus, the subsequent activities are blocked.
Effects of Allosteric Factors
There are some enzymes which have one active site and one or more regulatory sites and are known as allosteric enzymes. A molecule that binds with the regulatory sites are referred to as allosteric factor. When this molecule in the cellular environment forms a weak noncovalent bond at the regulatory site, the shape of the enzyme and its activation center get modified. This change usually decreases the enzyme activity as it inhibits the formation of a new enzyme-substrate complex. However, there are some allosteric activators that promote the affinity between the enzyme and the substrate and influence enzymatic behavior positively.
Hope this article helped you to get an overview about different factors that promote and inhibit the actions of various enzymes present in the living cells. We can conclude from the information provided here that all the enzymes require a favorable condition to function properly. An unfavorable condition tends to influence enzyme activity adversely.
http://www.buzzle.com/
Enzymes are protein-based complex molecules produced by the cells. There are several enzymes which are involved with different biochemical reactions. Each of these enzymes present in our body can influence any one particular chemical reaction or a set of reactions. They serve as organic catalysts and enhance the speed of the reactions in which they take part. In the absence of an enzyme, the speed of a chemical reaction becomes extremely slow. Some of these reactions may not occur if the right kind of enzyme is not present in the body.
Enzyme Activity Explained
An enzyme can increase the speed of a chemical reaction manifold. You will be surprised to know that studies have found that it can make a chemical reaction 10 billion times faster. The chemical substances that are present at the start of a biochemical process is termed as substrates which undergo chemical change(s) to form one or more end products. Basically, the active site of the enzymes forms a temporary bond with the substrate. During this time, an enzyme lowers the activation energy of the participant molecules which in turn speeds up the reaction. After the reaction is over, the newly formed product leaves the surface of the enzyme and the enzyme gets back its original shape. Thus, you can say it participates in the reaction without undergoing any physical or chemical change. Therefore, the same enzyme is used again and again for the specific process.
Factors Influencing Enzyme Activity
Concentrations of substrate and enzyme have an impact on the activity of the enzymes. Besides, environmental conditions such as temperature, pH values, presence of inhibitors, etc. also influence their activities. Each of these important factors have been discussed below:
Effects of Change in Temperature
All enzymes need a favorable temperature to work properly. The rate of a biochemical reaction increases with rise in temperature. This is because the heat enhances the kinetic energy of the participant molecules which results in more number of collisions between them. On the other hand, it is mostly found that in low temperature conditions, the reaction becomes slow as there is less contact between the substrate and the enzyme. However, extreme temperatures are not good for the enzymes. Under the influence of very high temperature, the enzyme molecule tends to get distorted, due to which the rate of reaction decreases. In other words, a denatured enzyme fails to carry out its normal functions. In the human body, the optimum temperature at which most enzymes become highly active lies in the range of 95 °F to 104 °F (35 °C to 40 °C). There are some enzymes that prefer a lower temperature than this.
Effects of Change in pH Value
The efficiency of an enzyme is largely influenced by the pH value of its surroundings. This is because the charge of its component amino acids changes with the change in the pH value. Each enzyme becomes active at a certain pH level. In general, most enzymes remain stable and work well in the pH range of 6 and 8. However, there are some specific enzymes which work well only in acidic or basic surroundings. The favorable pH value for a specific enzyme actually depends on the biological system in which it is working. When the pH value becomes very high or too low, then the basic structure of the enzyme undergoes change(s). As a result, the active site of the enzyme fails to bind well with the substrate properly and the activity of the enzyme gets badly affected. The enzyme may even stop functioning completely.
Effects of Substrate Concentration
Substrate concentration plays a major role in various enzyme activities. This is obviously because higher concentration of substrate means more number of substrate molecules are involved with the enzyme activity. Whereas, a low concentration of substrate means less number of molecules will get attached to the enzymes. This in turn reduces the enzyme activity. When the rate of an enzymatic reaction is maximum and the enzyme is at its most active state, an increase in the concentration of substrate will not make any difference in the enzyme activity. In this condition, the substrate is continuously replaced by new ones at the active site of the enzyme and there is no scope to add those extra molecules there.
Effects of Enzyme Concentration
In any enzymatic reaction, the quantity of substrate molecules involved is more as compared to the number of enzymes. A rise in enzyme concentration will enhance the enzymatic activity for the simple reason that more enzymes are participating in the reaction. The rate of the reaction is directly proportional to the quantity of enzymes available for it. However, that does not mean that a constant rise in concentration of enzymes will lead to a steady rise in the rate of reaction. Rather, a very high concentration of enzymes where all the substrate molecules are already used up does not have any impact on the reaction rate. To be precise, once the rate of reaction has attained stability, an increase in the quantity of enzymes does not affect the rate of reaction anymore.
Effects of Inhibitors
As the name suggests, inhibitors are those substances that have a tendency to prevent activities of the enzymes. Enzyme inhibitors interfere with the enzyme functions in two different ways. Based on this, they are divided into two categories: competitive inhibitors and noncompetitive inhibitors. A competitive inhibitor has a structure which is the same as that of a substrate molecule, and so it gets attached to the activated center of the enzyme easily and restricts the bond formation of enzyme-substrate complex. A noncompetitive inhibitor is the one which brings about change(s) in the shape of the enzymes by reacting with its active site. In this condition, the substrate molecule cannot bind itself to the enzyme and thus, the subsequent activities are blocked.
Effects of Allosteric Factors
There are some enzymes which have one active site and one or more regulatory sites and are known as allosteric enzymes. A molecule that binds with the regulatory sites are referred to as allosteric factor. When this molecule in the cellular environment forms a weak noncovalent bond at the regulatory site, the shape of the enzyme and its activation center get modified. This change usually decreases the enzyme activity as it inhibits the formation of a new enzyme-substrate complex. However, there are some allosteric activators that promote the affinity between the enzyme and the substrate and influence enzymatic behavior positively.
Hope this article helped you to get an overview about different factors that promote and inhibit the actions of various enzymes present in the living cells. We can conclude from the information provided here that all the enzymes require a favorable condition to function properly. An unfavorable condition tends to influence enzyme activity adversely.
http://www.buzzle.com/
Chromatography is a method used to separate different components of a mixture. There are different types of chromatography, but all of them are based on the same principle: the different molecules or ions in the mixture will interact differently with the stationary phase of the chromatograph, and get separated in the process. The different techniques of chromatography use different substances as the stationary and mobile phases. Chromatography can either be analytical or preparative. Analytical chromatography is used for determining the relative proportions of the different components in the mixture, while the separation of the different components is what preparative chromatography is used for.
Chromatography techniques are generally classified on the basis of the mechanism of separation. The types of chromatography, based on the mechanism of separation, are adsorption chromatography, partition chromatography, ion exchange chromatography, molecular exclusion chromatography, and affinity chromatography. Paper chromatography is based on the principle of partition chromatography.
Uses of Paper Chromatography
Paper chromatography is a simple chromatography technique which has many applications. Its main advantage is that it is not very expensive to perform, and provides clear results. Given below are some important uses of paper chromatography.
Obtain Pure Compounds
Paper chromatography is used to obtain pure compounds from a mixture. This is done by cutting out and redissolving the patterns formed by each constituent. Also, this technique can be effectively used to remove impurities from chemical compounds. Due to the process of paper chromatography, the impurities get separated from the compound and the pure compound can be obtained.
Qualitative Analysis of Drugs
Paper chromatography is one of the methods of qualitative analysis, to analyze or separate the different constituents of a mixture. It is a useful tool for separating polar as well as nonpolar solutes. Pharmaceutical companies use this technique to analyze the different compounds in drugs.
Forensic Science
Paper chromatography is useful in the field of forensic science, for investigation of crime. Samples from crime scenes are collected to be anaylzed and identified, using this technique.
Separating Colored Pigments
Paper chromatography is an effective technique for separating colored pigments from a mixture. Each pigment gets separated and rises up to a particular level on the chromatography paper.
Determining the Pollutants in Water
This technique is used to determine the pollutants or impurities in water bodies like rivers and lakes, by analyzing a small sample from the water body.
Analyzing Complex Mixtures
Paper chromatography is used to detect the presence of, or identify certain organic compounds such as carbohydrates and amino acids, from a complex mixture of organic compounds.
Pathology
Pathological laboratories use paper chromatography to detect the presence of alcohol or chemicals in blood. The fact that paper chromatography requires small samples, is very useful in pathological testing and diagnostics.
How Does Paper Chromatography Work
To understand the principle of paper chromatography, we must learn what is partition chromatography. As the name suggests, partition chromatography is a method of separating the components of a mixture in which the constituents of the mixture are partitioned or separated between two liquid phases, one of which is supported by a solid and is termed as the stationary phase. The other liquid phase is the solvent in which a small amount of the mixture (that is to be separated) is dissolved. In paper chromatography, the solid in question is a filter paper, and the stationary phase is water in the pores of the filter paper. The following are the steps to perform paper chromatography.
Step 1: Take a long rectangular piece of filter paper and draw a straight line on it using a pencil, a few centimeters above one of its shorter edges. This is your start line. Place a drop of the mixture on the start line, using a capillary tube.
Step 2: Take a glass jar and pour a small amount of the solvent liquid into it. Now, place the filter paper inside the glass jar such that the part of it below the start line, is submerged in the solvent. Do not disturb the setup and you shall see that the solvent in the jar slowly rises up due to the capillary action of the paper. Wait for around 15-20 minutes, till the solvent nearly reaches the top of the paper.
Step 3: Remove the filter paper from the jar and mark the highest point on the filter paper till which the solvent has risen. You shall see that the different components of the mixture have been carried to different levels, by the solvent. In the above diagram, you can see two colored spots formed by two different solutes, A and B. This is due to the difference in the affinity of the solutes present in the mixture, to the filter paper (stationary phase). So, while one solute (solute B) is easily carried farther away by the solvent, the other is not. This results in the solutes getting separated from the mixture.
Step 4: When the filter paper has dried, note the distance covered by each constituent from the start line. Now, calculate the retardation factor (Rf value) by the following formula. This value can never be more than 1, which implies that a solute can never travel ahead of the solvent.
Retardation Factor (Rf) = Distance traveled by the solute from the start lineDistance traveled by the solvent from the start line
Note: If the spot formed by a component is irregular, you need to measure the distance from the middle of the spot to the start line.
This was all about paper chromatography and its uses. However, while performing an experiment on paper chromatography, you need to follow each step carefully in order to get the desired results.
from:
http://www.buzzle.com/articles/paper-chromatography-uses.html
Chromatography techniques are generally classified on the basis of the mechanism of separation. The types of chromatography, based on the mechanism of separation, are adsorption chromatography, partition chromatography, ion exchange chromatography, molecular exclusion chromatography, and affinity chromatography. Paper chromatography is based on the principle of partition chromatography.
Uses of Paper Chromatography
Paper chromatography is a simple chromatography technique which has many applications. Its main advantage is that it is not very expensive to perform, and provides clear results. Given below are some important uses of paper chromatography.
Obtain Pure Compounds
Paper chromatography is used to obtain pure compounds from a mixture. This is done by cutting out and redissolving the patterns formed by each constituent. Also, this technique can be effectively used to remove impurities from chemical compounds. Due to the process of paper chromatography, the impurities get separated from the compound and the pure compound can be obtained.
Qualitative Analysis of Drugs
Paper chromatography is one of the methods of qualitative analysis, to analyze or separate the different constituents of a mixture. It is a useful tool for separating polar as well as nonpolar solutes. Pharmaceutical companies use this technique to analyze the different compounds in drugs.
Forensic Science
Paper chromatography is useful in the field of forensic science, for investigation of crime. Samples from crime scenes are collected to be anaylzed and identified, using this technique.
Separating Colored Pigments
Paper chromatography is an effective technique for separating colored pigments from a mixture. Each pigment gets separated and rises up to a particular level on the chromatography paper.
Determining the Pollutants in Water
This technique is used to determine the pollutants or impurities in water bodies like rivers and lakes, by analyzing a small sample from the water body.
Analyzing Complex Mixtures
Paper chromatography is used to detect the presence of, or identify certain organic compounds such as carbohydrates and amino acids, from a complex mixture of organic compounds.
Pathology
Pathological laboratories use paper chromatography to detect the presence of alcohol or chemicals in blood. The fact that paper chromatography requires small samples, is very useful in pathological testing and diagnostics.
How Does Paper Chromatography Work
To understand the principle of paper chromatography, we must learn what is partition chromatography. As the name suggests, partition chromatography is a method of separating the components of a mixture in which the constituents of the mixture are partitioned or separated between two liquid phases, one of which is supported by a solid and is termed as the stationary phase. The other liquid phase is the solvent in which a small amount of the mixture (that is to be separated) is dissolved. In paper chromatography, the solid in question is a filter paper, and the stationary phase is water in the pores of the filter paper. The following are the steps to perform paper chromatography.
Step 1: Take a long rectangular piece of filter paper and draw a straight line on it using a pencil, a few centimeters above one of its shorter edges. This is your start line. Place a drop of the mixture on the start line, using a capillary tube.
Step 2: Take a glass jar and pour a small amount of the solvent liquid into it. Now, place the filter paper inside the glass jar such that the part of it below the start line, is submerged in the solvent. Do not disturb the setup and you shall see that the solvent in the jar slowly rises up due to the capillary action of the paper. Wait for around 15-20 minutes, till the solvent nearly reaches the top of the paper.
Step 3: Remove the filter paper from the jar and mark the highest point on the filter paper till which the solvent has risen. You shall see that the different components of the mixture have been carried to different levels, by the solvent. In the above diagram, you can see two colored spots formed by two different solutes, A and B. This is due to the difference in the affinity of the solutes present in the mixture, to the filter paper (stationary phase). So, while one solute (solute B) is easily carried farther away by the solvent, the other is not. This results in the solutes getting separated from the mixture.
Step 4: When the filter paper has dried, note the distance covered by each constituent from the start line. Now, calculate the retardation factor (Rf value) by the following formula. This value can never be more than 1, which implies that a solute can never travel ahead of the solvent.
Retardation Factor (Rf) = Distance traveled by the solute from the start lineDistance traveled by the solvent from the start line
Note: If the spot formed by a component is irregular, you need to measure the distance from the middle of the spot to the start line.
This was all about paper chromatography and its uses. However, while performing an experiment on paper chromatography, you need to follow each step carefully in order to get the desired results.
from:
http://www.buzzle.com/articles/paper-chromatography-uses.html
Langganan:
Postingan (Atom)
