...Challenge Entropy, Enthalpy, and Free Energy The equation relating these factors is: ∆G = ∆H–T∆S, where G is free energy, H is enthalpy, S is entropy, and T is temperature (in Kelvin). Although temperature values will always be positive, entropy, enthalpy, and free energy values can be positive or negative. For a given process, a quantitative value for each factor can be calculated using the known values of the factors for each reactant involved (see Table 1) according to the general equation ∆ X°rx = Σ X°(products)–Σ X°(reactants). See if the following activity helps you better understand what these quantities really mean. Table 1 HCO3 H+ H2O (l) CO2 (g) - ∆Η° (kJ/mol) -691.1 0 -285.8 -393.5 S° (J/K mol) 94.94 0 69.9 213.6 ∆G° (kJ/mol) -587.1 0 -237.2 -394.4 Materials • • • • • vinegar baking soda thin-walled cup tablespoon measure teaspoon measure Exploration Step 1 Put about 2 tablespoons vinegar in a cup. Add a teaspoon or two of baking soda to the cup. (a) What do you observe through sight, sound, and touch? (b) What kind of change is occurring? (c) What are the formulas of the 2 major components of vinegar and of the one component of baking soda? (d) Write the overall equation and the net ionic equation for the process. Step 2 (a) Define entropy and the significance of the sign of its value. (b) Based on your observations, explain the entropy change for the system observed in Step 1. (c) Use the entropy data from Table 1 to calculate the entropy change...
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...surroundings. A spontaneous process is capable of proceeding in a given direction, as written or described, without needing to be driven by an outside source of energy. The term is used to refer to macro processes in which entropy increases; such as a smell diffusing in a room, ice melting in lukewarm water, salt dissolving in water, and iron rusting. The laws of thermodynamics govern the direction of a spontaneous process, ensuring that if a sufficiently large number of individual interactions (like atoms colliding) are involved then the direction will always be in the direction of increased entropy (since entropy increase is a statistical phenomenon). Entropy is a chemical concept that is very difficult to explain, because a one-sentence definition will not lead to a comprehensive statement. Thus, few people understand what entropy really is. You are not alone if you have some difficulty with this concept. The word entropy is used in many other places and for many other aspects. We confine our discussion to thermodynamics (science dealing with heat and changes) and to chemical and physical processes. We have defined energy as the driving force for changes; entropy is also a driving force for physical and chemical changes (reactions). Entropy, symbol S, is related to energy, but it a different aspect of energy. This concept was developed over a long period of time. Human experienced chemical and physical changes that cannot be explained by energy...
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...SAFETY HANDBOOK Student’s name Course title Date Safety Handbook Introduction Safety is the state of serenity being devoid of harm or any form of event that may be considered non-desirable. In any type of institution, be it, a business, school, industry, laboratory or even the common workplace, safety plays a major role in ensuring activities run smoothly and no-one gets hurt while doing their job. Safety encompasses protection from a wide host of potential hazards which could be physical, financial, emotional or biological. In the common workplace health is a major concern and infection control is the main aim of a safety handbook. Biosafety in the work setup starts by assuming every individual is a potential source of infection. Basic techniques such as scheduled cleaning of the workplace and regular hand washing by staff go a long way in ensuring infection control and biosafety of workers. All workplaces should ideally possess appropriate safety apparatus e.g. a first aid kit with an employee having necessary expertise in first aid. Provision of necessary safety equipments e.g. gowns, gloves and goggles is also essential in as far as biosafety in the workplace is concerned. General Principles Disease is caused by organisms termed pathogens. There are various pathogens that are located routinely in work setups. These include bacteria, fungi, viruses, prions or protozoa. When these manage to enter your body or attach onto your skin, disease arises. It usually takes...
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...oxygen get electrons and become reduced, so this reaction is redox reaction. In cellular respiration, C-H bond are broken and release energy as the electrons from hydrogen form H-O bonds in water, so this reaction is endergonic. according to the second law of thermodynamics------every energy transfer or transformation increases the entropy of the universe, which also can be understood that during every energy transfer or transformation, some energy becomes unavailable to do work, like heat. we use this equation to show energy transfer or tranformation,ΔG means The change in free energy; ΔH symbolizes the change in the system’s total energy; ΔS is the change in the system’s entropy; and T is the absolute temperature in Kelvin (K) units. When ΔG is negative, mean the reaction can happen spontaneously, release energy; if posivitive, need energy input. autotrophs capture Light energy by photosynthesis, energy transformed from light energy into chemical energy stored in organic molecules like sugar, some is lost as heat when chlorophyll’s electrons go back to its ground state from exited state. ΔG is positive, andΔS is negative, thus entropy is decreased. In cellular...
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...Nernst Heat Theorem Introduction : In the chemical thermodynamics, it was difficult to find a quantitative relation between ∆G and ∆H in chemical reaction. & To find out ∆G from thermal data i.e.… ∆H Various attempts to relate ∆G & ∆H are as follow (1) Joule-thomsan concept : They found that ∆G & ∆H values are same in case of Daniel cell :: they proposed that ∆G & ∆H are identical. (2) Berthelot’s concept : He suggested that “when heat is given out in a reaction, the free energy of System decreases. ” qt describes the qualitative relationship between ∆G & ∆H qt was found to be true in case of condensed system at ordinary imperative but failed in no. of other cases. (3) Gibbs – Helmholtz Concept : For the first time they deduced quantitative relation between ∆G & ∆H by the Gibbs – Helmholtz equation, The limitation of the Gibbs- Helmholtz equation that it does not allow to calculate ∆G from thermal date i.e. ∆H. *1* (4) Richard’s concept: In 1902 Richard measured the emf of cells at law temperature and Concluded that…… ∂ (∆G / ∂T) gets decreased gradually with lowering of temperatures. i.e. ∆G and ∆H approach each other marl closely at extremely low temperature. i.e. Lit ∆G = ∆H T -> O * The Nernst Heat Theorem: From the data of Richard in 1906, Nernst postulated that………. “For a process in condensed system...
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...BSc MPC PHYSICAL CHEMISTRY 1030242 PART A Q 1 Q 2 Q 3 Q 4 Q 5 Q 6 Q 7 Q 8 Q 9 Q 10 PART B Q 11 Q 12 Q 13 Q 14 b photosensitization, the process of initiating a reaction through the use of a substance capable of absorbing light and transferring the energy to the desired reactants. The technique is commonly employed in photochemical work, particularly for reactions requiring light sources of certain wavelengths that are not readily available. A commonly used sensitizer is mercury, which absorbs radiation at 1849 and 2537 angstroms; these are the wavelengths of light produced in high-intensity mercury lamps. Also used as sensitizers are cadmium; some of the noble gases, particularly xenon; zinc; benzophenone; and a large number of organic dyes. In a typical photosensitized reaction, as in the photodecomposition of ethylene to acetylene and hydrogen, a mixture of mercury vapour and ethylene is irradiated with a mercury lamp. The mercury atoms absorb the light energy, there being a suitable electronic transition in the atom that corresponds to the energy of the incident light. In colliding with ethylene molecules, the mercury atoms transfer the energy and are in turn deactivated to their initial energy state. The excited ethylene molecules subsequently undergo decomposition. Another mode of photosensitization observed in many reactions involves direct participation of the sensitizer in the reaction itself. Q 15 b Polarization (also polarisation) is a property that describes...
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...Sierra Sisson Mrs. Webb PWC Period 7 December 2nd, 2013 1. What is the impact of entropy on a steam engine? A steam engine could not function without entropy. Entropy is what is quantified when the substances in a system reach thermal equilibrium, and thermal equilibrium is another thing that the engine would not be able to function without either. Once the coal is heated up by the fire/source of heat in the engine so that it reaches thermal equilibrium with the heat source, the resulting energy is then converted into work, which is what the steam engine needs to function. 2. Why does heat energy only flow from hot areas or materials to colder areas? This is because of thermodynamics; substances want to be at thermal equilibrium. Obviously, this means that they are both at the same temperature and will not change any more. If a hot substance and a cold substance are beside each other, the hotter substance will transfer its heat to the colder substance so that they become equal to each other in temperature. 3. What does the author mean by thermal equilibrium? They have given the definition of thermal equilibrium to be what is achieved when the substances in a system have reached the same exact temperature and do not change any further. They also get a bit more specific in saying that it also means that “the system is not only in thermal, but also in mechanical, chemical as well as radioactive equilibrium.” 4. What happens when a thermometer reaches a person’s body...
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...The Second Law of Thermodynamics The second law of thermodynamics says that the entropy of any segregated framework dependably increments. Confined frameworks suddenly advance towards warm balance—the condition of most extreme entropy of the framework. All the more basically: the entropy of the universe (a definitive disconnected framework) just increments and never diminishes. A basic approach to think about the second law of thermodynamics is that a room, if not cleaned and cleaned, will perpetually turn out to be more muddled and confused with time - paying little respect to that one is so watchful to keep it clean. At the point when the room is cleaned, its entropy diminishes, yet the push to clean it has brought about an expansion in entropy outside the room that surpasses the entropy lost. The Third Law of Thermodynamics The third law of thermodynamics expresses that the entropy of a framework methodologies a steady esteem as the temperature approaches supreme zero. The entropy of a framework at supreme zero is regularly zero, and in all cases is resolved just by the quantity of various ground states it has. In particular, the entropy of an unadulterated crystalline substance (immaculate request) at total zero temperature is zero. This announcement remains constant if the ideal precious stone has stand out state with least vitality. Source: Boundless. "The Three Laws of Thermodynamics." Boundless Chemistry. Vast, 03 Feb. 2016. Recovered 14 Apr. 2016 from...
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...first, second, and third law were already widely understood and recognized. Hence it was numbered the zeroth law. The importance of the zeroth law as a foundation to the earlier laws is that it defines temperature in a non-circular logistics without reference to entropy, its conjugate variable. • First law is nothing but a connotation of Energy Conservation • Second Law of Thermodynamics has been formulated differently by many scientists like Kelvin, Planck, Clausius and Caratheodory. But this law is the outcome of a very basic fact that Entropy of a spontaneous system always increases. Entropy is also defined qualitatively as Disorder of state. This is a common experienced fact that if let on its own, the disorder of a system always increases and work has to be done to bring it back in order. • According to the second law the entropy of any isolated system, such as the entire universe, never decreases. If the entropy of the universe has a maximum upper bound then when this bound is reached the universe has no thermodynamic free energy to sustain motion or life, that is, the heat death is reached. • The famous theory of evolution violates our Second Law of thermodynamics. Second law states that the entropy (disorder) of an isolated system always increases. Considering the Universe is an isolated system, various stages in Theory of evolution like Big Bang, or even our improvement in all respects since ever clearly goes against the law that disorder always increases...
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...Chemistry note on thermodynamics A born haber cycle= a thermochemical cycle that includes all the enthalpy changes involved in the formation of an ionic compound. e.g the born haber cycle for sodium chloride if we know any five we can calculate the other: starting from the elements in their standard states. Na s -> Na g +108kjmol-1 ½ CL2-> Cl g +122kjmol-1 Na g -> Na+ + e- +496kjmol-1 Cl g + e+ -> Cl- g -349kjmol-1 Na s + ½ Cl2 -> NaCl s -411kjmol-1 When drawing the born haber cycles: * Make up a rough scale 1 line of paper to 100kjmol-1 * Plan out roughly first to avoid going off the top or bottom of the paper. The zero line representing elements in their standard state will need to be in the middle of the paper. * Remember to put in the sign of each enthalpy change and an arrow to show its direction. Possitive enthalpy changes go up, negative enthalpy changes go down. Using born haber cycle we are able to see the formation of an ionic compound from its elements is an exothermic process. This is mainly due to the large amount of energy given out when the lattice forms. 1. Elements in their standard states. This is the energy zero of the diagram 2. Add in the atomisation of sodium. This is positive, drawn uphill. 3. Add in the atomisation of chlorine. This is positive, drawn uphill. 4. Add in the ionisation of sodium, also posstive, drawn uphill. 5. Add in the electron affinity of chlorine. This is negative...
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...Introduction Thermodynamics is the area of science that includes the relationship between heat and other kinds of energy. Thermodynamics was discovered and studied beginning in the 1800s. At that time, it was linked to and gained importance because of the use of steam engines. Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Nicolas Leonard Sadi Carnot . Who believed that the efficiency of heat engines was the key that could help France win the Napoleonic Wars.[1] Scottish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854. Thermodynamics is built on the study of energy transfers that can be strictly resolved into two distinct components, heat and work, specified by macroscopic variables.[17] Though thermodynamics originated in the study of cyclic non-equilibrium processes such as the working of heat engines, study of the subject gradually revealed that the notion of heat is inextricably tied to the notion of thermodynamic equilibrium.[18]Thermodynamics is well understood and validated for systems in thermodynamic equilibrium, but as the systems of interest become further and further from thermodynamic equilibrium, their thermodynamical study becomes more and more difficult. Systems in thermodynamic equilibrium have very well experimentally reproducible behaviour, and as interest moves further towards non-equilibrium systems...
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...Wars.[1] Scottish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854:[2] Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency. Initially, the thermodynamics of heat engines concerned mainly the thermal properties of their 'working materials', such as steam. This concern was then linked to the study of energy transfers in chemical processes, for example to the investigation, published in 1840, of the heats of chemical reactions[3] by Germain Hess, which was not originally explicitly concerned with the relation between energy exchanges by heat and work. Chemical thermodynamics studies the role of entropy in chemical reactions.[4][5][6][7][8][9][10][11][12] Also, statistical thermodynamics, or statistical mechanics, gave explanations of macroscopic thermodynamics by statistical predictions of the collective motion of particles based on the mechanics of their microscopic behavior. Thermodynamics describes how systems change when they interact with one another or with their surroundings. This can be applied to a wide variety of topics in science...
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...Plant Cell versus Solar Cell Katrina Minchew July 18, 2011 Strayer University | | Photosynthesis is defined as the process in which green plants and other organisms by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source. It takes place mainly inside the leaves. This process utilizes light energy and it is transformed into chemical energy used to create organic compounds. Photosynthesis consists of two processes that use both light and dark energy. The first process, light reaction transforms light into energy. The second process utilizes dark reactions, use the energy and carbon dioxide to produce sugar. The process needs sunlight, water, and carbon dioxide. These materials are transported through the leaves. Water is absorbed by the plant through the roots and is then delivered to the leaves through the plant tissue. The carbon dioxide is absorbed through small holes in plant leaves known as stomata. It also releases oxygen. The process known as chlorophyll is when the green pigment of plants and photosynthetic algae and bacteria trap the energy of sunlight. In plants, photosynthesis takes place inside the chloroplasts, which is the organelle that carries out photosynthesis and starch grain formation. A chlorophyll-containing organelle in plants is the site of photosynthesis. A solar cell also known as the photovoltaic cell is a solid state electrical mechanism that converts the energy of light directly into electricity...
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...is going to happen, almost. A tiny start-up in US is set to launch an engine that requires no fuel, yes, no fuel. The other features- it produces no pollution, and runs nearly everywhere- are a bonus. Entropy Systems, a seven-person start-up based in Youngstown, Ohio, is the company behind this and is planning to launch this engine-- named the Entropy engine--early next year. For Indians the matter of pride is that the technology's inventor, Sanjay Amin, a mechanical engineer, is an Indian and also the co-founder of the company. The Entropy engine converts heat to mechanical power. Any mechanical power over and above friction losses can then be converted to electricity by coupling an electric generator to the output shaft of the engine. Conventional engines can only convert high temperature heat to power, by burning fossil fuels. The engine takes room temperature air, absorbs heat from the air like a sponge, converts, that heat to power and exhausts air at a lower temperature. This low-temperature exhaust can be used for refrigeration and air conditioning. Thus the Entropy engine is both an engine and a refrigerator. An electric generator coupled to this engine produces electricity and has a higher efficiency rating than conventional engines. How it works--The Entropy engine (named after the unit in physics that describes the amount of available energy in a system) absorbs heat from the atmosphere and converts it to power. Since it consumes no fossil fuels, nuclear fuels...
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...even exist? Things that you can expect are that time moves forward, people will die, mathematical constants, and an interesting thing called the Second Law of Thermodynamics. The Second Law(it's that important) of Thermodynamics says that entropy in a closed system always increases. The repercussions that it has are phenomenal, scientists use it as a way to measure time, likelihood of recurrence in a system, and even going back to discover why entropy was low at the beginning of the universe. So what is entropy? It's the measure of chaos within a system or the usefulness of an object. There's an interesting quotation about entropy: "The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation."- Eddington It's easy to tell there's not much that's more constant than that. Entropy in a closed system always increases, why does it matter? Imagine a bowl of sand, one side, exactly red and the other exactly blue. If you mix up the grains of sand, returning them to that state would take a very long time. Why? There are...
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