THEORETICAL YIELD AND PRECNTAGE YIELD

Hii guys ,
 In this topic I am going  to  share  some ideas about how you can calculate yield of the compound  which can be obtained  in chemical reactions or used  in chemical reactions. Because it's very important thing for pharmaceuticals industry because we have save the money  we have give  100% productivity then Very important to konw  exactly how amount  or how much  percentage we get after  the process.
The world of pharmaceutical production is an expensive one. Many drugs have several steps in their synthesis and use costly chemicals. A great deal of  researchers takes place to develop better ways to make drugs faster and more efficiently. Studying how much of a compound is produced in any given reaction is an important part of cost control.     

Percent Yield

Chemical reactions in the real world don’t always go exactly as planned on paper. In the course of an experiment  things will contribute to the formation of less product than would be predicted. Besides spills and other experimental errors, there are usually losses due to an incomplete reaction, undesirable side reactions, etc. Chemists need a measurement that indicates how successful a reaction has been. This measurement is called the percent yield.

To compute the percent yield, it is first necessary to determine how much of the product should be formed based on stoichiometry. This is called the theoretical yield, the maximum amount of product that could be formed from the given amounts of reactants. The actual yield is the amount of product that is actually formed when the reaction is carried out in the laboratory The percent yield is the ratio of the actual yield to the theoretical yield, expressed as a percentage.

Percent Yield=Actual YieldTheoretical Yield×100%

Percent yield is very important in the manufacture of products. Much time and money is spent improving the percent yield for chemical production. When complex chemicals are synthesized by many different reactions, one step with a low percent yield can quickly cause a large waste of reactants and unnecessary expense.

Typically, percent yields are understandably less than 100% because of the reasons indicated earlier. However, percent yields greater than 100% are possible if the measured product of the reaction contains impurities that cause its mass to be greater than it actually would be if the product was pure. When a chemist synthesizes a desired chemical, he or she is always careful to purify the products of the reaction.

Sample Problem: Calculating the Theoretical Yield and the Percent Yield

Potassium chlorate decomposes upon slight heating in the presence of a catlyst according to the reaction below:

Sample Problem: Calculating the Theoretical Yield and the Percent Yield

Potassium chlorate decomposes upon slight heating in the presence of a catlyst according to the reaction below:

2KClO3(s)→2KCl(s)+3O2(g)

In a certain expriment,40.0 g KClO3 is heated until it completely decomposes. What is the theoretical yield of oxygen gas? 

The experiment is performed and the oxygen gas is collected and its mass is found to be 14.9 g. What is the percent yield for the reaction?

First, we will calculate the theoretical yield based on the stoichiometry.

Step 1: List the known quantities and plan the problem.

Known

• given: mass of KClO3 = 40.0 g
• molar mass KClO3 = 122.55 g/mol
• molar mass O2 = 32.00 g/mol

Unknown

• theoretical yield O2 = ? g

Apply stoichiometry to convert from the mass of a reactant to the mass of a product:

g KClO3→mol KClO3→mol O2→g O2

Step 2: Solve.

40.0 g KClO3×1 mol KClO3122.55 g KClO3×3 mol O22 mol KClO3×32.00 g O21 mol O2=15.7 g O2

The theoretical yield of O2 is 15.7 g.

Step 3: Think about your result.

The mass of oxygen gas must be less than the 40.0 g of potassium chlorate that was decomposed.

Now, we use the actual yield and the theoretical yield to calculate the percent yield.

Step 1: List the known quantities and plan the problem.

Known

• Actual yield = 14.9 g
• Theoretical yield = 15.7 g (from Part 12.11A)

Unknown

• Percent yield = ? %

Percent Yield=Actual YieldTheoretical Yield×100%

Use the percent yield equation above.

Step 2: Solve.

Percent Yield=14.9 g15.7 g×100=94.9%

Step 3: Think about your result.

Since the actual yield is slightly less than the theoretical yield, the percent yield is just under 100%.

solid-state sodium-ion battery

Hi everyone today am sharing some information about solid state sodium ion battery this research  by

University of Housto .

Solid-state sodium-ion batteries are far safer than conventional lithium-ion batteries, which pose a risk of fire and explosions, but their performance has been too weak to offset the safety advantages. Researchers Friday reported developing an organic cathode that dramatically improves both stability and energy density.

The improved performance, reported in the journal Joule, is related to two key findings:

• The resistive interface between the electrolyte and cathode that commonly forms during cycling can be reversed, extending cycle life, and
• The flexibility of the organic cathode allowed it to maintain intimate contact at the interface with the solid electrolyte, even as the cathode expanded and contracted during cycling.

Yan Yao, associate professor of electrical and computer engineering at the University of Houston and corresponding author of the paper, said the organic cathode—known as PTO, for pyrene-4,5,9,10-tetraone—offers unique advantages over previous inorganic cathodes. But he said the underlying principles are equally significant.

"We found for the first time that the resistive interface that forms between the cathode and the electrolyte can be reversed," Yao said. "That can contribute to stability and longer cycle life." Yao also is a principal investigator at the Texas Center for Superconductivity at UH. His research group focuses on green and sustainable organic materials for energy generation and storage.

Yanliang "Leonard" Liang, a research assistant professor in the UH Department of Electrical and Computer Engineering, said that reversibility of the interface is the key, allowing the solid-state battery to reach a higher energy density without sacrificing cycle life. Normally, a solid-state battery's ability to store energy is halted when the resistive cathode?electrolyte interface forms; reversing that resistance allows energy density to remain high during cycling, he said.

Lithium-ion batteries with their liquid electrolytes are able to store relatively high amounts of energy and are commonly used to power the tools of modern life, from cell phones to hearing aids. But the risk of fire and explosion has heightened interest in other types of batteries, and a solid-state sodium-ion battery offers the promise of increased safety at a lower cost.

Xiaowei Chi, a post-doctoral researcher in Yao's group, said a key challenge had been to find a solid electrolyte that is as conductive as the liquid electrolytes used in lithium-ion batteries. Now that sufficiently conductive solid electrolytes are available, a remaining challenge has been the solid interfaces.

Xiaowei Chi, a post-doctoral researcher in Yao's group, said a key challenge had been to find a solid electrolyte that is as conductive as the liquid electrolytes used in lithium-ion batteries. Now that sufficiently conductive solid electrolytes are available, a remaining challenge has been the solid interfaces.

One issue raised by a solid electrolyte: the electrolyte struggles to maintain intimate contact with a traditional rigid cathode as the latter expands and contracts during battery cycling. Fang Hao, a Ph.D. student working in Yao's group, said the organic cathod is more pliable and thus able to remain in contact with the interface, improving cycling life. The researchers said the contact remained steady through at least 200 cycles.

"If you have reliable contact between the electrode and electrolyt you will have a great chance of creating a high-performance solid-state battery," Hao said.

CHEMISTRY OF GUNPOWDER

Gunpowder is a mixture of potassium nitrate, carbon, and sulfur. Since it is a mixture, it does not, strictly speaking, have a formula. The standard composition for black powder (i.e, Proportions by weight) are 75%potassium nitrate , 15% Carbon, and 10% sulfur.

Sulfur's main role in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be

6 KNO3 + C7H4O → 3 K2CO3 + 4 CO2 + 2 H2O + 3 N2.

With the Fourth of July and American Independence Day on the horizon, a somehow topical post seemed in order. Having already examined the chemical compounds that give fireworks their colours . I decided to examine another important firework component here: the first chemical explosive, gunpowder, also commonly referred to as black powder.
Until the mid-19th Century, gunpowder was the only known chemical explosive. Its use can be traced much earlier than this, however, and there are historical accounts of its use in fireworks in China as far back as 1200AD. In subsequent centuries it had military applications in rifles and cannons, but in these it has long since been replaced by modern, smokeless powders. The fireworks industry is one of the last major industries that still uses traditional black powder.

Rather than being one particular compound, gunpowder is actually a mix of three different components. It consists of potassium nitrate (75% by weight), charcoal (15% by weight), and sulfur (10% by weight). Each of these components plays an important role in the combustion of gunpowder.

Potassium nitrate, also known as ‘saltpetre’, or ‘saltpeter’, decomposes at high temperature to provide oxygen for the reaction. This means that gunpowder doesn’t need to be exposed to air to burn – and is why smothering fireworks won’t stop them burning! The charcoal is often represented simply as being a source of carbon, which acts as a fuel, though it’s actually a broken down form of cellulose, with the approximate empirical formula C7H4O. Finally, the sulfur can also act as a fuel, though its inclusion has more to do with the fact that it undergoes exothermic reactions (reactions that give off heat) at relatively low temperatures, providing more energy and lowering the ignition temperature of the charcoal.
It’s worth noting that just mixing these three constituents together isn’t enough to produce good quality gunpowder; they must be thoroughly mixed, moistened and ground to produce a reactive mixture. Deviations from the ideal ratio given above are sometimes utilised to alter the burning behaviour of the mixture, and the addition of small amounts of water to the mixture can also be used to extend the burning time.
The precise reactions of gunpowder are difficult to elucidate. Rather than being a simple single reaction, the combustion of gunpowder consists of many differing complex reactions. It’s possible, however, to provide simplified equation that provides an overall idea of the products of the various reactions, as shown in the graphic. A mixture of solid and gaseous products are produced by the reactions, along with a very small amount of water.
The obvious use for black powder in firework is as the ‘lift charge’, which propels the firework into the air. The fuse, which allows the delay before the bursting of the firework, and the bursting charge itself, will also utilise gunpowder. The burning of the charcoal in gunpowder is often the source of the sparkling tails of fireworks as they ascend. The gases produced by the combustion reaction are the causes of the propellant effect, and the eventual bursting of the firework.

List of reagents in organic chemistry

Hii everyone I am going share some idea about how many reagents are present in organic chemistry based on current data which I have  so let see, first I am going to tell you what is reagents?
So Reagents are "substances or compounds that are added to a system in order to bring about a chemical reaction or are added to see if a reaction occurs.Some reagents are just a single element. However, most processes require reagents made of chemical compound Some of the most common ones.
Types of reagents ;

Acetic acid: an organic acid is one of the simplest carboxylic acid . systematically named ethanoic acid is a colourless liquid organic compound with the chemical formula CH₃COOH (also written as CH₃CO₂H or C₂H₄O₂). When undiluted, it is sometimes called glacial acetic acid. Vingar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. Acetic acid has a distinctive sour taste and pungent smell. In addition to household vinegar, it is mainly produced as a precursor to polyvinyl acetate and cellulose acetate It is classified as a weak acid  only partially dissociated in solution, but concentrated acetic acid is corrosive and can attack the skin.
This acid is an important chemical reagent and industrial chemical useful for the production of various synthetic fibers and other polymeric materials. These polymers include polyethylene terephthalate, used mainly in soft drink bottles; cellulose acetate used mainly for photographic film; and polyvinyl acetate, for wood glue. In households, diluted acetic acid is often used in descaling agents. The food industry uses it (under the food additive code E260) as an acidity regulator.

Acetone ;  an  organic compound with the formula (CH₃)₂CO. It is a colorless, volatile, flammable liquid and is the simplest and smallest ketone.

Acetone is misible with water and serves as an important solvent in its own right, typically for cleaning purposes in laboratories. About 6.7million tonnes were produced worldwide in 2010, mainly for use as a solvent . It is a common building block in organic chemistry Familiar household uses of acetone are as the active ingredient in nail polish remover and as paint thinner.Acetone is produced and disposed of in the human body through normal metabolic processes. It is normally present in blood and urine.

Acetylene;( systematic name Ethyne ) is the chemical compound with the formula C₂H₂. It is a hydrocarbon and the simplest alkyne.this is colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities.

As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond  The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°.
Ammonia : 
 Compound of nitrogen and hydrogen with the formula NH3 The simplest pnictogen hydride ammonia is a colourless gas with a characteristic pungent smell. It is a common nitrogenous west particularly among aquatic organisms, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food fertilizer. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceutical  compound and is used in many commercial cleaning products. It is mainly collected by downward displacement of both air and water. Ammonia is named for the Ammonians, worshipers of the Egyptian god Amun who used ammonium chloride in their rituals.

Ammonium hydroxide: 
 also known as ammonia water, ammonia solution, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH₃(aq). Although the name ammonium hydroxide suggests an alkali with composition [NH₄⁺][OH⁻], it is actually impossible to isolate samples of NH₄OH. The ions NH₄⁺ and OH⁻ do not account for a significant fraction of the total amount of ammonia except in extremely dilute solutions.

Azobisisobutyronitrile (abbreviated AIBN): is an organic compound with the formula [(CH₃)₂C(CN)]₂N₂. This white powder is soluble in alcohols and common organic solvents but is insoluble in water. It is often used as a foamer in plastic and rubber and as a radical initiators.


Baeyer's reagents : is an alkaline solution of potassium permanganate; used in organic chemistry as a qualitative test for the presence of unsaturation, such as double bonds.

World's fastest hydrogen sensors

Hii everyone I am going to share some important things on hydrogen as sensors how it can help for us and how it is work its most important part because we all know hydrogen is present very large amount so we can use for so many thing .
 So sensors hydrogen is good thing for current world let see how it work
Credit; a Ph.D. student Ferry Nugroho and his supervisor Christoph Langhamme.

Hydrogen is a clean and renewable energy carrier that can power vehicles, with water as the only emission. Unfortunately, hydrogen gas is highly flammable when mixed with air, so very efficient and effective sensors are needed. Now, researchers from Chalmers University of Technology, Sweden, present the first hydrogen sensors ever to meet the future performance targets for use in hydrogen powered vehicles.

The researchers' ground-breaking results were recently published in the prestigious scientific journal Nature Materials. The discovery is an optical nanosensor encapsulated in a plastic material. The sensor works based on an optical phenomenon – a plasmon – which occurs when metal nanoparticles are illuminated and capture visible light. The sensor simply changes colour when the amount of hydrogen in the environment changes.

The plastic around the tiny sensor is not just for protection, but functions as a key component. It increases the sensor's response time by accelerating the uptake of the hydrogen gas molecules into the metal particles where they can be detected. At the same time, the plastic acts as an effective barrier to the environment, preventing any other molecules from entering and deactivating the sensor. The sensor can therefore work both highly efficiently and undisturbed, enabling it to meet the rigorous demands of the automotive industry – to be capable of detecting 0.1 percent hydrogen in the air in less than a second.

"We have not only developed the world's fastest hydrogen sensor, but also a sensor that is stable over time and does not deactivate. Unlike today's hydrogen sensors,our solution does not need to be recalibrated as often, as it is protected by the plastic," says Ferry Nugroho, a researcher at the Department of Physics at Chalmers.

It was during his time as a Ph.D. student that Ferry Nugroho and his supervisor Christoph Langhammer realised that they were on to something big. After reading a scientific article stating that no one had yet succeeded in achieving the strict response time requirements imposed on hydrogen sensors for future hydrogen cars, they tested their own sensor. They realised that they were only one second from the target – without even trying to optimise it. The plastic, originally intended primarily as a barrier, did the job better than they could have imagined, by also making the sensor faster. The discovery led to an intense period of experimental and theoretical work.

In that situation, there was no stopping us. We wanted to find the ultimate combination of nanoparticles and plastic, understand how they worked together and what made it so fast. Our hard work yielded results. Within just a few months, we achieved the required response time as well as the basic theoretical understanding of what facilitates it," says Ferry Nugroho.

Detecting hydrogen is challenging in many ways. The gas is invisible and odourless, but volatile and extremely flammable. It requires only four percent hydrogen in the air to produce oxyhydrogen gas, sometimes known as knallgas, which ignites at the smallest spark. In order for hydrogen cars and the associated infrastructure of the future to be sufficiently safe, it must therefore be possible to detect extremely small amounts of hydrogen in the air. The sensors need to be quick enough that leaks can be rapidly detected before a fire occurs.

"It feels great to be presenting a sensor that can hopefully be a part of a major breakthrough for hydrogen-powered vehicles. The interest we see in the fuel cell industry is inspiring," says Christoph Langhammer, Professor at Chalmers Department of Physics.

Although the aim is primarily to use hydrogen as an energy carrier, the sensor also presents other possibilities. Highly efficient hydrogen sensors are needed in the electricity network industry, the chemical and nuclear power industry, and can also help improve medical diagnostics.

"The amount of hydrogen gas in our breath can provide answers to, for example, inflammations and food intolerances. We hope that our results can be used on a broad front. This is so much more than a scientific publication," says Christoph Langhammer.

In the long run, the hope is that the sensor can be manufactured in series in an efficient manner, for example using 3-D printer technology.

Facts: The world's fastest hydrogen sensor

• The Chalmers-developed sensor is based on an optical phenomenon – a plasmon – which occurs when metal nanoparticles are illuminated and capture light of a certain wavelength.
• The optical nanosensor contains millions of metal nanoparticles of a palladium-gold alloy, a material which is known for its sponge-like ability to absorb large amounts of hydrogen. The plasmon effect then causes the sensor to change colour when the amount of hydrogen in the environment changes.
• The plastic around the sensor is not only a protection, but also increases the sensor's response time by facilitating hydrogen molecules to penetrate the metal particles more quickly and thus be detected more rapidly. At the same time, the plastic acts as an effective barrier to the environment because no other molecules than hydrogen can reach the nanoparticles, which prevents deactivation.
• The efficiency of the sensor means that it can meet the strict performance targets set by the automotive industry for application in hydrogen vehicles of the future by being capable of detecting 0.1 percent hydrogen in the air in less than one second.
• The research was funded by the Swedish Foundation for Strategic Research, within the framework of the Plastic Plasmonics project.