pH, pKa, Ka, pKb, and Kb Explained

There are related scales in chemistry used to measure how acidic or basic a solution is and the strength of acids and bases. Although the pH scale is most familiar, pKa, Ka, pKb, and Kb are common calculations that offer insight into acid-base reactions. Heres an explanation of the terms and how they differ from each other. What Does the p Mean? Whenever you see a p in front of a value, like pH, pKa, and pKb, it means youre dealing with a -log of the value following the p. For example, pKa is the -log of Ka. Because of the way the log function works, a smaller pKa means a larger Ka. pH is the -log of hydrogen ion concentration, and so on. Formulas and Definitions for pH and Equilibrium Constant pH and pOH are related, just as Ka, pKa, Kb, and pKb are. If you know pH, you can calculate pOH. If you know an equilibrium constant, you can calculate the others. About pH pH is a measure of hydrogen ion concentration, [H], in an aqueous (water) solution. The pH scale ranges from 0 to 14. A low pH value indicates acidity, a pH7 is neutral, and a high pH value indicates alkalinity. The pH value can tell you whether youre dealing with an acid or a base, but it offers limited value indicating the true strength of the acid of a base. The formula to calculate pH and pOH are: pH - log [H] pOH - log [OH-] At 25 degrees Celsius: pH pOH 14 Understanding Ka and pKa Ka, pKa, Kb, and pKb are more helpful for predicting whether a species will donate or accept protons at a specific pH value. They describe the degree of ionization of an acid or base and are true indicators of acid or base strength because adding water to a solution will not change the equilibrium constant. Ka and pKa relate to acids, while Kb and pKb deal with bases. Like pH and pOH, these values also account for hydrogen ion or proton concentration (for Ka and pKa) or hydroxide ion concentration (for Kb and pKb). Ka and Kb are related to each other through the ion constant for water, Kw: Kw Ka x Kb Ka is the acid dissociation constant. pKa is simply the -log of this constant. Similarly, Kb is the base dissociation constant, while pKb is the -log of the constant. The acid and base dissociation constants are usually expressed in terms of mole per liter (mol/L). Acids and bases dissociate according to general equations: HA H2O ⇆ A-Â   H3OHB H2O ⇆ B OH- In the formulas, A stands for acid and B for base. Ka [H][A-]/ [HA]pKa - log Kaat half the equivalence point, pH pKa -log Ka A large Ka value indicates a strong acid because it means the acid is largely dissociated into its ions. A Large Ka value also means the formation of products in the reaction is favored. A small Ka value means little of the acid dissociates, so you have a weak acid. The Ka value for most weak acids ranges from 10-2 to 10-14. The pKa gives the same information, just in a different way. The smaller the value of pKa, the stronger the acid. Weak acids have a pKa ranging from 2-14. Understanding Kb and pKb Kb is the base dissociation constant. The base dissociation constant is a measure of how completely a base dissociates into its component ions in water. Kb [B][OH-]/[BOH]pKb -log Kb A large Kb value indicates the high level of dissociation of a strong base. A lower pKb value indicates a stronger base. pKa and pKb are related by the simple relation: pKa pKb 14 What Is pI? Another important point is pI. This is the isoelectric point. It is the pH at which a protein (or another molecule) is electrically neutral (has no net electrical charge).

Is Third Worlld Immigration a Threat to Americas Way of Life

Is Third Worlld Immigration a Threat to Americas Way of Life Is Third world immigration a threat to America’s way of life? I do not believe it is. I agree with Isbister. He argues that cultural impacts of immigration â€Å"are positive, constructive changes, that most Americans will benefit from living in a more multicultural society, and that tension between the different ethnic groups can be alleviated. I for one am a Filipino-American and proud of it. My parents came to America from the Philippines to make a better life for themselves. They came here for the so-called â€Å"American Dream.† My parents believed in all the sayings about â€Å"The Land of Opportunity and â€Å"The Land of Milk and Honey.† I honestly believe that they have made their†¦show more content†¦One reason why people oppose it is because they believe that immigrants may take away jobs from American workers. Another issue is that they believe immigrants may cause the country to break up into separate cultural units, thus destroying Amer ica’s unity. Lastly, people say that immigrants are a fiscal burden. Isbister tells us that cross-sectional studies show that â€Å"immigration has little if any impact on the wages and employment opportunities of residents, even residents who are unskilled, low paid, or racial minorities.† This and other cross-sectional empirical studies show that immigration quite possibly may have little or no effect at all on employment and wages of current residents. In regards to the issue that immigrants may try to break the country up into separate units. I believe this is preposterous. I think that the only reason why people believe in this is because they are ignorant to other cultures and feel threatened because of their differences. I think that Isbister said it best with the this statement, â€Å"The essence of American life is that it is composed of different groups, different cultures, races, religions, attitudes, folkways and ideologies, differences that give the count ry its distinctiveness.† In concern with the issue that immigrants are a fiscal burden there is no proof that this is true. There have been studies made that claim â€Å"†¦immigrants have not been a burden to U.S. governments- that government expenditures on the immigrants

Newspapers as Sources for Historians free essay sample

This paper provides an analysis of several themes found in the newspapers of the time of World War II on December 15 1941, and how they were used by historians. This essay discusses several themes found in the newspapers of the time of the Second World War on the day of December 15 1941 , showing the usefulness as well as ineffectiveness of these sources for historians. The author examines sources that include authentic documents, personal accounts, diaries, memoirs, and newspapers. By researching and studying various aspects of newspapers from times of war, we are able to determine their usefulness to historians as sources. Newspapers contain a wide variety of information on many different subjects, some of which are useful and some of which prove inadequate. Newspapers, especially during times of war, contain large amounts of factual information, such as accounts of battles and gains and losses of military assets. By studying the way in which this information is expressed in newspapers, and by comparing it to other sources, we are able to conclude that this factual information contained in newspapers is usually incorrect, inaccurate or misleading. We will write a custom essay sample on Newspapers as Sources for Historians or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page In this sense, newspapers prove useless to historians as a source. In contrast, newspapers prove to be extremely useful as a source for determining both social and political attitudes of the time.

Hydrogen As Fuel Internal Combustion Engineâ€Myassignmenthelp.Com

Question: Discuss About The Hydrogen As Fuel Internal Combustion Engine? Answer: Introducation The energy sector is undergoing different changes and different suggestions to overcome the different challenges in the industry. The environmental impacts are taking the center and therefore raising different researches to focus on other sources of energy to fuel the machines rather than fossil fuels. The analysis of hydrogen to be used as a fuel for internal combustion engine has been carried out for long and at some point looks much more promising to solve the different challenges (Rahman, Mohammed and Bakar, 2008). Even with the various advantages, hydrogen as well has some pros, which has been able to challenge its implementation as part of fuel for internal combustion engine. Hydrogen-fueled internal combustion engines (H2ICEs) has been a topic f focus and trial for several decades and several tests have been as well carried to evaluate the effect of use of hydrogen in this sector. The hydrogen internal combustion engine came in place in order to replace the traditional gasolin e engines. This part of this paper will mostly focus on the different elements of use of the hydrogen in the HICE rather than the differences on the engines. The use of hydrogen as a fuel is able to lead to production of water, which is emitted (Verhelst, Verstraeten and Sierens, 2014). Unlike the other denser field, which led to production of oxides of nitrogen, which are harmful to the environment, the production of water is friendly. The hydrogen fuel engines are able to burn fuel in the same manner as the gasolines engines do burn. Power output is a key factor, which is considered when adopting an engine. The air/fuel ratio and fuel injection methods are the major factors, which determine the power output for the hydrogen fueled engines. A stoichiometric air/fuel of 34:1 of hydrogen is usually used in these engines. Using this ratio, hydrogen is likely to replace 29% of the combustion chamber content and therefore leaving the 71% for air (Antunes, Gomes, Mikalsen and Roskilly, 2008). With the increase of the air content, the energy content is likely to be less than when gasoline is used as a fuel. This ratio is able to reduce the power output in the hydrogen engines. There are two key methods, which are mostly used, which include carbureted and port injection methods in the mixing of air and fuel before it enters the combustion chamber. The use of these methods in the internal combustion engine may result to either a 15% increase or decrease in the energy output for the engines. Metering of the fuel is key in d etermination of the theoretical power output in the engines. The metering of the fuel is able to contribute to the output of the power on these hydrogen engines. The hydrogen fueled engines are designs to twice the air in order to complete the combustion. The ratio of air and fuel are key in the production of nitrogen oxides. The use of hydrogen and the control of the ratio are able to lower the production of nitrogen oxides to near zero in these hydrogen fueled engines (Priyanka, and Sharma, 2014). The main use of the hydrogen as a fuel in the energy production is to reduce the production of the nitrogen oxides. Combustion properties of hydrogen are superior in terms of advantages achieved. Hydrogen as a fuel has a high flame velocity, which enhance its burning to produce power output. The use of the hydrogen as a fuel is able to increase the efficiency of operation through increase of power output. Flammability is another key factor, which is needed for fuels. Hydrogen has a wide range of flammability enhances wider operation of the engines. Complete burning of fuel is likely to happen and this leads to fuel economy. In addition, hydrogen a s a fuel has a high diffusivity. Formation of uniform airflow is usually achieved through the adoption of the hydrogen as a fuel (Verhelst, Maesschalck, Rombaut, and Sierens, 2009). In addition, through the diffusivity, if any leakage is able to happen the hydrogen is usually able to disperse it immediately and therefore lead to control of hazards. In addition, hydrogen has low density. The low density is advantageous in terms of weight but has some disadvantages. Large volume of hydrogen is usually require to cover a room unlike gasoline, which is dense. Secondly, reduced power output is usually related to the low density of hydrogen. Nevertheless, the use of hydrogen as a fuel in internal combustion engine is gaining its popularity. The need to enhance environmental factors, which gasoline and other fuel are causing, is able to promote the use of hydrogen. Merits and demerits of using hydrogen as a fuel The use of hydrogen as a fuel is able to bring various advantages to the industry. First and foremost, hydrogen is environmental friendly and its by product does not pollute the environment. This is one of the key advantage of adapting hydrogen as fuel unlike other fuels. When burned, hydrogen does not produce carbon and nitrogen oxides, which are widely produced by other fuels (Rude, et al., 2011). Additionally, hydrogen is non-toxic and this means that it is environmentally friendly. In terms if final products, when burnt hydrogen is able to produce water as the final product. This product is environmentally friendly and therefore the hydrogen as a fuel does not conflict the environmental existence. Gasoline and nuclear energy are able to produce other products, which are toxic to the environment. Products of carbon and nitrogen oxides by these other duels are able to deplete the ozone layer and therefore leading to global warming (Kim, Lee and Choi, 2012). This is able to affect t he climatic conditions and therefore affecting the ecosystem as a whole. This is a great advantage, which is able to promote the use of hydrogen as a fuel a part from the other fuels. Therefore, the adoption of hydrogen as a fuel is able to bring positive impacts to the environment than the other fuels, which destroy it much. In addition, hydrogen is readily available and therefore a source which can last. Fossil fuels can be extinguished from their sources and therefore relying on them means that some point the sources will be no more. Hydrogen fuel is more powerful; in fact, it is three times more powerful than other fuels. This means that the adoption of hydrogen as a fuel will be able to fuel all the machines unlike other fuels, which means that some machines such as rockets must search for other alternatives for fuel (Balat, 2008). Efficiency is a key factor when adopting any fuel. Hydrogen is able to lead to high efficiency and therefore enhancing its use. Hydrogen is able to produce three times efficiency when used as a fuel more than other fuels. This is a great advantage, which is achieved when there is fuel is adopted in the industry and therefore it enhances the operations. More importantly, hydrogen is renewable and this means that it can be used repeatedly unlike the nonrenewable energy fuels . The hydrogen fuel is available and can be produced to meet the demands, which may arise. This means that shortage cannot be experiences when adoption of the hydrogen fuel is done (Glassman, 2012). Since hydrogen can be sourced automatically or produced using water, the fuel has a future to meet further demands. Other fuel sources are able to be depleted with time and this places a risk on the emerging demand of fuel in different industries. A source, which can be able to withstand the increased demand, is therefore needed and the hydrogen fuel is able to generate hopes of that source and fuel. Demerits Hydrogen use as a fuel does not only have the positive part but also has some dark areas on it. First, hydrogen production process is expensive therefore meaning that the final end product will be expensive too. The process of production is long and requires large efforts to bring out the hydrogen as a fuel (Kelly, Gibson Ouwerkerk, 2008). When compared with other fuels, it is cheaper to produce them than the production of hydrogen. Additionally, transportation and storage of hydrogen as a fuel is not easy. Since the fuel will not only be used at the point of production, its transportation and storage becomes an expensive affair. Other fuels have transportation mechanisms such as pipeline and trucks, which enhance their storage and transportation to consumption points in an easy way. This makes them cheap to consumers. Transporting hydrogen fuel to consumers will make it more expensive for them to afford it for their use. In addition, hydrogen is highly flammable and this means that special mechanism for its forage will be required. The handling of the fuel then becomes an issue, which will affect its usage as a fuel due to flammability. Moreover, the production of the hydrogen will require other energy sources (Swain and Adt, 2010). This means that the usage of other sources such as gasoline will not be evaded at all. The production process for the hydrogen will require these sources to complete the process. This is unlike these sources, which are able to run their parts in order to refine the fuels. Therefore even with the numerous advantages which the hydrogen fuel is able to bring, there are few hurdles, which need to be jumped for effective implementation of this energy References Antunes, F., Gomes, M.J., Mikalsen, R. and Roskilly, A.P. (2008). An Investigation of Hydrogen Fuelled HCCI Engine Performance and Operation. International Journal of Hydrogen Energy, 33(15):5823-5828. Balat, M. (2008). Potential Importance of Hydrogen as a Future Solution to Environment and Transportation Problems. International Journal of Hydrogen Energy, 33(15):4013-4029. Glassman, I. (2012). Combustion. Academic Press, Inc California. Kelly, N.A., Gibson T. L. Ouwerkerk D. B. (2008). A Solar-Powered, High-Efficiency Hydrogen Fueling System using High Pressure Electrolysis of Water: Design and Initial Results. International Journal of Hydrogen Energy; (18): 2747-2764. Kim, Y.Y., Lee T.J., and Choi, H.G. (2012). An Investigation on the Causes of Cycle Variation in Direct Injection Hydrogen Fueled Engines. International Journal of Hydrogen Energy, (1):69-76. Priyanka, G., and Sharma, S.K., (2014). Review on Opportunities and Difficulties with HCNG as a Future Fuel for Internal Combustion Engine. Advances in Aerospace Science and Application, Research India Publication; 4(1):79-84.Balat, M. (2008). Potential importance of hydrogen as a future solution to environmental and transportation problems. International Journal of Hydrogen Energy, 33(15): 4013-4029. Rahman, M.M., Mohammed, M.K., and Bakar, R.A. (December 2008). Effect of Engine Speed on Performance of Four-Cylinder Direct Injection Hydrogen Fueled Engine. Proceedings of the 4th BSME-ASME International Conference on Thermal Engineering, Dhaka, Bangladesh, 27-29, 175-200. Rude, L.H., Nielsen, T.K., Ravnsbk, D.B., Bosenberg, Ley, M.B., Richter, B. (2011). Tailoring Properties of Borohydrides for Hydrogen Storage: A Review. Phys Status Solidi (a); 208(8):175473. Swain, M.R. and Adt. R.R. (2010). The Hydrogen-Air Fuelled Automobile, Proc. 7th Intersociety Energy Conversion Engineering Conference; 1382-1388. Verhelst, S., Maesschalck, P., Rombaut, N., and Sierens, R. (2009). Increasing the Power Output of Hydrogen Internal Combustion Engines by means of Supercharging and Exhaust Gas Recirculation. International Journal of Hydrogen Energy, 34(10): 44064412. Verhelst, S., Verstraeten, S., and Sierens, R. (2014). A Comprehensive Overview of Hydrogen Engine Design Features. J. 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