2023 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. Heat is another form of energy transfer, but its one that takes place when two objects are at different temperatures to each other. Please note that the amount of heat energy before and after the chemical change remains the same. When physical or chemical changes occur, they are generally accompanied by a transfer of energy. The reaction is exothermic and thus the sign of the enthalpy change is negative. How can endothermic reaction be spontaneous? When a value for H, in kilojoules rather than kilojoules per mole, is written after the reaction, as in Equation \(\ref{5.4.10}\), it is the value of H corresponding to the reaction of the molar quantities of reactants as given in the balanced chemical equation: \[ 2Al\left (s \right )+Fe_{2}O_{3}\left (s \right ) \rightarrow 2Fe\left (s \right )+Al_{2}O_{3}\left (s \right ) \;\;\;\; \Delta H_{rxn}= - 851.5 \; kJ \label{5.4.10} \]. (CC BY-NC-SA; anonymous). The internal energy \(U\) of a system is the sum of the kinetic energy and potential energy of all its components. The system is performing work by lifting the piston against the downward force exerted by the atmosphere (i.e., atmospheric pressure). Enthalpy \(\left( H \right)\) is the heat content of a system at constant pressure. Then, the change in enthalpy is actually: For more particular problems, we can define the standard enthalpy of formation of a compound, denoted as HfH_\mathrm{f}\degreeHf. Unless otherwise specified, all reactions in this material are assumed to take place at constant pressure. The direction of the reaction affects the enthalpy value. Solution: Given parameters are, m= 100g Since heat absorbed by the salt will be the same as Heat lost by water. For example, water (like most substances) absorbs heat as it melts (or fuses) and as it evaporates. Step 1: Calculate the amount of energy released or absorbed (q) q = m Cg T. When heat is absorbed, the change is said to be endothermic, and the numerical value of the heat is given a positive sign (q > 0). Enthalpy measures the total energy of a thermodynamic system either in the form of heat or volume multiplied by pressure. 002603 u and 12 u respectively. The Zeroth Law of Thermodynamics, 13.6 - The Kinetic Theory of Gases. It is important to include the physical states of the reactants and products in a thermochemical equation as the value of the \(\Delta H\) depends on those states. Heat energy absorbed or released by a substance with or without change of state. \(1.1 \times 10^8\) kilowatt-hours of electricity. Because so much energy is needed to melt the iceberg, this plan would require a relatively inexpensive source of energy to be practical. Here are the molar enthalpies for such changes: The heat absorbed or released by a process is proportional to the moles of substance that undergo that process. Whether it's to pass that big test, qualify for that big promotion or even master that cooking technique; people who rely on dummies, rely on it to learn the critical skills and relevant information necessary for success. How do you calculate heat absorbed by a calorimeter? The \(89.6 \: \text{kJ}\) is slightly less than half of 198. (B) In this part, in knowing that you use "excess oxygen", you assume that "SO"_2(g) is the limiting reagent (i.e. Energy released should be a positive number. Know the heat capacity formula. Sulfur dioxide gas reacts with oxygen to form sulfur trioxide in an exothermic reaction, according to the following thermochemical equation. The Black Hole Collision Calculator lets you see the effects of a black hole collision, as well as revealing some of the mysteries of black holes, come on in and enjoy! The main issue with this idea is the cost of dragging the iceberg to the desired place. Notice that the second part closely remembers the equations we met at the combined gas law calculator: the relationship between pressure and volume allows us to find a similar connection between quantity of matter and temperature. If you seal the end of a syringe and push on the plunger, is that process isothermal? We'll show you later an example that should explain it all. However, the water provides most of the heat for the reaction. H = heat change. An example is if you have #"1 mol"# of an ideal gas that reversibly expands to double its volume at #"298.15 K"#. The First Law of Thermodynamics and Heat Here are the molar enthalpies for such changes:\r\n
- \r\n \t
- \r\n
Molar enthalpy of fusion:
\r\n![\"Molar](\"https://www.dummies.com/wp-content/uploads/476684.image5.jpg\")
\r\n \t - \r\n
Molar enthalpy of vaporization:
\r\n![\"Molar](\"https://www.dummies.com/wp-content/uploads/476685.image6.jpg\")
\r\n
![\"Delta](\"https://www.dummies.com/wp-content/uploads/476682.image3.png\")
\r\n\r\nrefers to the enthalpy change for one mole equivalent of the reaction. Now, consider another path of the reaction. Where. maximum efficiency). Read on to learn how to calculate enthalpy and its definition. The standard enthalpy of formation formula for a reaction is as follows: If you're paying attention, you might have observed that Hf(products)H_\mathrm{f}\degree(\mathrm{products})Hf(products) and Hf(reactants)H_\mathrm{f}\degree(\mathrm{reactants})Hf(reactants) have different units than HreactionH\degree_\mathrm{reaction}Hreaction. He is the coauthor of Biochemistry For Dummies and Organic Chemistry II For Dummies. To find enthalpy change: Use the enthalpy of product NaCl ( -411.15 kJ ). For an isothermal process, S = __________? But they're just as useful in dealing with physical changes, like freezing and melting, evaporating and condensing, and others. During an isothermal process, 5.0 J of heat is removed from an ideal gas. In the field of thermodynamics and physics more broadly, though, the two terms have very different meanings. For example, a large fire produces more heat than a single match, even though the chemical reactionthe combustion of woodis the same in both cases. In short, the heat capacity tells you how much heat energy (in joules) is needed to raise the temperature of 1 kg of a material by 1 degree C. The specific heat capacity of water is 4,181 J / kg degree C, and the specific heat capacity of lead is 128 J/ kg degree C. This tells you at a glance that it takes less energy to increase the temperature of lead than it does water. The chemical equation of the reaction is: $$\ce {NaOH (s) +H+ (aq) + Cl- (aq) -> Na+ (aq) +Cl- (aq) + H2O (l)}$$ This is the ONLY information I can use and I cannot search up anything online. You can find the change in temperature by subtracting the starting temperature from the final temperature. If a chemical reaction is carried out inside a calorimeter, the heat evolved or absorbed by the reaction can be determined. Determine math tasks. Put a solid into water. (A metric ton is 1000 kg. {"appState":{"pageLoadApiCallsStatus":true},"articleState":{"article":{"headers":{"creationTime":"2016-03-26T07:53:40+00:00","modifiedTime":"2021-07-23T16:32:07+00:00","timestamp":"2022-09-14T18:18:28+00:00"},"data":{"breadcrumbs":[{"name":"Academics & The Arts","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33662"},"slug":"academics-the-arts","categoryId":33662},{"name":"Science","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33756"},"slug":"science","categoryId":33756},{"name":"Chemistry","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33762"},"slug":"chemistry","categoryId":33762}],"title":"How to Calculate Endothermic and Exothermic Reactions","strippedTitle":"how to calculate endothermic and exothermic reactions","slug":"how-to-calculate-endothermic-and-exothermic-reactions","canonicalUrl":"","seo":{"metaDescription":"Chemical reactions transform both matter and energylearn about two types of heat reactions in this article: endothermic and exothermic. She holds a Bachelor of Science in cinema and video production from Bob Jones University. To find the heat absorbed by the solution, you can use the equation hsoln = q n. Because the heat is absorbed by the system, the \(177.8 \: \text{kJ}\) is written as a reactant. The mass of sulfur dioxide is slightly less than \(1 \: \text{mol}\). The system is the specific portion of matter in a given space that is being studied during an experiment or an observation. For example, water (like most substances) absorbs heat as it melts (or fuses) and as it evaporates. If youre trying to calculate how much heat is absorbed by something when you raise its temperature, you need to understand the difference between the two and how to calculate one from the other. The free space path loss calculator allows you to predict the strength of a radio frequency signal emitted by an antenna at any given distance. The thermochemical reaction is shown below. This allows us to calculate the enthalpy change for virtually any conceivable chemical reaction using a relatively small set of tabulated data, such as the following: The sign convention is the same for all enthalpy changes: negative if heat is released by the system and positive if heat is absorbed by the system. From Equation \(\ref{5.4.5}\) we see that at constant pressure the change in enthalpy, \(H\) of the system, is equal to the heat gained or lost. Download full answer. The second law of thermodynamics dictates that heat only flows from hotter objects to colder ones, not the other way around. Measure and record the solution's temperature before you heat it. Our pressure conversion tool will help you change units of pressure without any difficulties! In everyday language, people use the terms heat and temperature interchangeably. The heat released in a reaction is automatically absorbed by the bomb calorimeter device. . The thermochemical reaction can also be written in this way: \[\ce{CH_4} \left( g \right) + 2 \ce{O_2} \left( g \right) \rightarrow \ce{CO_2} \left( g \right) + 2 \ce{H_2O} \left( l \right) \: \: \: \: \: \Delta H = -890.4 \: \text{kJ}\nonumber \]. The reaction is highly exothermic. For example, water (like most substances) absorbs heat as it melts (or fuses) and as it evaporates. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. But an element formed from itself means no heat change, so its enthalpy of formation will be zero. This change of thermal energy in the thermodynamic system is known as change of enthalpy or delta h written as H in chemistry and calculated using the formula H = cmT. Possible sources of the approximately \(3.34 \times 10^{11}\, kJ\) needed to melt a \(1.00 \times 10^6\) metric ton iceberg. #w_(rev) = -int_(V_1)^(V_2) PdV = -q_(rev)#. We will also explain the difference between endothermic and exothermic reactions, as well as provide you with an example of calculations. Plugging in the values given in the problem . Dummies helps everyone be more knowledgeable and confident in applying what they know. Just as with \(U\), because enthalpy is a state function, the magnitude of \(H\) depends on only the initial and final states of the system, not on the path taken. Here's an example:\r\n\r\n![\"A](\"https://www.dummies.com/wp-content/uploads/476683.image4.jpg\")
\r\n\r\nThis reaction equation describes the combustion of methane, a reaction you might expect to release heat. In the course of an endothermic process, the system gains heat from the surroundings and so the temperature of the surroundings decreases. The total mass of the solution is 1.50g + 35.0g = 36.5g. He is the coauthor of Biochemistry For Dummies and Organic Chemistry II For Dummies. I calculated: Remember to multiply the values by corresponding coefficients! Find the solution's specific heat on a chart or use the specific heat of water, which is 4.186 joules per gram Celsius. All Your Chemistry Needs. When heat is . Substitute the solution's mass (m), temperature change (delta T) and specific heat (c) into the equation Q = c x m x delta T, where Q is the heat absorbed by the solution. Heat Absorbed Or Released Calculator Input Values Mass of substance ( m) kg Specific heat capacity of substance in the solid state ( c s) = J/kgC Specific heat capacity of substance in the liquid state ( c) = J/kgC Specific heat capacity of substance in the gaseous state ( c g) = J/kgC Specific latent heat of fusion of substance ( L f) = J/kg T = temperature difference. Use your experimental data to calculate the energy absorbed by the solution. At constant pressure, heat flow equals enthalpy change:\r\n\r\n![\"Heat](\"https://www.dummies.com/wp-content/uploads/476680.image1.jpg\")
\r\n\r\nIf the enthalpy change listed for a reaction is negative, then that reaction releases heat as it proceeds the reaction is exothermic (exo- = out). If the enthalpy change listed for the reaction is positive, then that reaction absorbs heat as it proceeds the reaction is endothermic (endo- = in). In other words, exothermic reactions release heat as a product, and endothermic reactions consume heat as a reactant.\r\nThe sign of the\r\n![\"The](\"https://www.dummies.com/wp-content/uploads/476681.image2.png\")
\r\n\r\ntells you the direction of heat flow, but what about the magnitude? We can summarize the relationship between the amount of each substance and the enthalpy change for this reaction as follows: \[ - \dfrac{851.5 \; kJ}{2 \; mol \;Al} = - \dfrac{425.8 \; kJ}{1 \; mol \;Al} = - \dfrac{1703 \; kJ}{4 \; mol \; Al} \label{5.4.6a} \]. If you're given the amount of energy used, the mass, and initial temperature, here's how to calculate the final temperature of a reaction. Peter J. Mikulecky, PhD, teaches biology and chemistry at Fusion Learning Center and Fusion Academy. have a standard enthalpy of formation zero. The most straightforward answer is to use the standard enthalpy of formation table! Calculate the heat capacity of the calorimeter in J/C. Calculate the moles of water formed during the reaction given the volumes and molarities of reactants used and then determine the amount of heat released by the reaction, q rxn. The overall amount of heat q = q 1 + q 1 = 11,724 J or 11.7 kJ with three significant digits. If more energy is produced in bond formation than that needed for bond breaking, the reaction is exothermic and the enthalpy is negative. Here's an example: This reaction equation describes the combustion of methane, a reaction you might expect to release heat. Calculate heat absorption using the formula: Q = mc T Q means the heat absorbed, m is the mass of the substance absorbing heat, c is the specific heat capacity and T is the change in temperature. \[\ce{CaCO_3} \left( s \right) \rightarrow \ce{CaO} \left( s \right) + \ce{CO_2} \left( g \right) \: \: \: \: \: \Delta H = 177.8 \: \text{kJ}\nonumber \]. This raises the temperature of the water and gives it energy. An equation which shows both mass and heat relationships between products and reactants is called a thermochemical equation. 2023 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. Running a process in reverse produces heat flow of the same magnitude but of opposite sign as running the forward process. However, the water provides most of the heat for the reaction. Chemical reactions transform both matter and energy. The more interesting quantity is the change of enthalpy the total energy that was exchanged within a system. Thus H = 851.5 kJ/mol of Fe2O3. Check out 42 similar thermodynamics and heat calculators , Standard enthalpy of formation table and definition. Step 2:. This equation is given . Assuming all of the heat released by the chemical reaction is absorbed by the calorimeter system, calculate q cal. - q neutralization = q cal The heat of neutralization is the heat evolved (released) when 1 mole of water is produced by the reaction of an acid and base. Whether you need help solving quadratic equations, inspiration for the upcoming science fair or the latest update on a major storm, Sciencing is here to help. Subjects: Chemistry. The enthalpy change listed for the reaction confirms this expectation: For each mole of methane that combusts, 802 kJ of heat is released. If the enthalpy change listed for the reaction is positive, then that reaction absorbs heat as it proceeds the reaction is endothermic (endo- = in). The calculation requires two steps. If you want to cool down the sample, insert the subtracted energy as a negative value. The formula of the heat of solution is expressed as, H water = mass water T water specific heat water. We believe everyone should have free access to Physics educational material, by sharing you help us reach all Physics students and those interested in Physics across the globe. Example #4: A student wishes to determine the heat capacity of a coffee-cup calorimeter. "Calculating the Final Temperature of a Reaction From Specific . b). Simplify the equation. Chemistry problems that involve enthalpy changes can be solved by techniques similar to stoichiometry problems. The change in enthalpy of a reaction is a measure of the differences in enthalpy of the reactants and products. K1 and a mass of 1.6 kg is heated from 286. For example, freezing 1 mol of water releases the same amount of heat that is absorbed when 1 mol of water melts. heat of reaction, also called enthalpy of reaction, the amount of heat that must be added or removed during a chemical reaction in order to keep all of the substances present at the same temperature. H = H of products - H of reactants . So reaction enthalpy changes (or reaction "heats") are a useful way to measure or predict chemical change. The salt water absorbed 18,837 joules of heat. n = number of moles of reactant. Ice absorbs heat when it melts (electrostatic interactions are broken), so liquid water must release heat when it freezes (electrostatic interactions are formed): \( \begin{matrix} or for a reversible process (i.e. This allows us to allocate future resource and keep these Physics calculators and educational material free for all to use across the globe. Heat the solution, then measure and record its new temperature. (CC BY-NC-SA; anonymous). But before that, you may ask, "How to calculate standard enthalpy of formation for each compound?" Exothermic reactions have negative enthalpy values (-H). If you're given the amount of energy used, the mass, and initial temperature, here's how to calculate the final temperature of a reaction. At constant pressure, heat flow equals enthalpy change: If the enthalpy change listed for a reaction is negative, then that reaction releases heat as it proceeds the reaction is exothermic ( exo- = out). Step 2: Write the equation for the standard heat of formation. Figure \(\PageIndex{2}\): The Enthalpy of Reaction. S surr = -H/T. -571.7 kJ. Calculate heat absorbed by water: q absorbed = m water C g T = 25 4.184 49.7 = 5 200 J = 5 200 J 1000 J/kJ = 5.20 kJ Heat absorbed by water = heat released by combustion of 0.50 g of bread = 5.20 kJ heat released per gram of bread = 5.20 kJ 0.5 g = 10.4 kJ heat released by 100 g of bread = 10.4 kJ 100 = 1040 kJ \end{matrix} \label{5.4.7} \), \( \begin{matrix} At constant pressure, heat flow equals enthalpy change:\r\n\r\n\r\n\r\nIf the enthalpy change listed for a reaction is negative, then that reaction releases heat as it proceeds the reaction is exothermic (exo- = out). If the enthalpy change listed for the reaction is positive, then that reaction absorbs heat as it proceeds the reaction is endothermic (endo- = in). In other words, exothermic reactions release heat as a product, and endothermic reactions consume heat as a reactant.\r\nThe sign of the\r\n\r\n\r\ntells you the direction of heat flow, but what about the magnitude? Step 1: Identify the mass and the specific heat capacity of the substance. The heat absorbed when hydrated salt (Na 2 CO3.10H 2 O . According to the reaction stoichiometry, 2 mol of Fe, 1 mol of Al2O3, and 851.5 kJ of heat are produced for every 2 mol of Al and 1 mol of Fe2O3 consumed: \[ 2Al\left (s \right )+Fe_{2}O_{3}\left (s \right ) \rightarrow 2Fe\left (s \right )+Al_{2}O_{3}\left (s \right )+ 815.5 \; kJ \label{5.4.9} \]. Subtract its initial temperature from its final temperature. energy = energy released or absorbed measured in kJ. Question: Calculate the amount of energy released (or absorbed) during the step of the triple-\alpha shown below. Enthalpy in chemistry determines the heat content of a system. Our equation is: Heat Capacity = E / T. [1] The heat flow for a reaction at constant pressure, q p, is called enthalpy, H. Enthalpies of Reaction. Energy changes in chemical reactions are usually measured as changes in enthalpy. We are given H for the processthat is, the amount of energy needed to melt 1 mol (or 18.015 g) of iceso we need to calculate the number of moles of ice in the iceberg and multiply that number by H (+6.01 kJ/mol): \[ \begin{align*} moles \; H_{2}O & = 1.00\times 10^{6} \; \cancel{\text{metric ton }} \ce{H2O} \left ( \dfrac{1000 \; \cancel{kg}}{1 \; \cancel{\text{metric ton}}} \right ) \left ( \dfrac{1000 \; \cancel{g}}{1 \; \cancel{kg}} \right ) \left ( \dfrac{1 \; mol \; H_{2}O}{18.015 \; \cancel{g \; H_{2}O}} \right ) \\[5pt] & = 5.55\times 10^{10} \; mol \,\ce{H2O} \end{align*} \], B The energy needed to melt the iceberg is thus, \[ \left ( \dfrac{6.01 \; kJ}{\cancel{mol \; H_{2}O}} \right )\left ( 5.55 \times 10^{10} \; \cancel{mol \; H_{2}O} \right )= 3.34 \times 10^{11} \; kJ \nonumber \]. Heat Absorbed During a Reaction (Example) 13,871 views Jan 22, 2014 43 Dislike Share Save LearnChemE 151K subscribers Organized by textbook: https://learncheme.com/ Calculate the amount of. Upper Saddle River, New Jersey 2007. One way to report the heat absorbed or released would be to compile a massive set of reference tables that list the enthalpy changes for all possible chemical reactions, which would require an incredible amount of . What happens to particles when a substance gains energy and changes state? To determine the amount of heat energy absorbed by a solution, you must do more than find its temperature. If \(H\) is 6.01 kJ/mol for the reaction at 0C and constant pressure: How much energy would be required to melt a moderately large iceberg with a mass of 1.00 million metric tons (1.00 106 metric tons)? This is because you need to multiply them by the number of moles, i.e., the coefficient before the compound in the reaction. 8.8: Enthalpy Change is a Measure of the Heat Evolved or Absorbed is shared under a CK-12 license and was authored, remixed, and/or curated by Marisa Alviar-Agnew & Henry Agnew. In other words, the entire energy in the universe is conserved. One way to report the heat absorbed or released would be to compile a massive set of reference tables that list the enthalpy changes for all possible chemical reactions, which would require an incredible amount of effort. What causes energy changes in chemical reactions? She has acted as a copywriter and screenplay consultant for Advent Film Group and as a promotional writer for Cinnamom Bakery. Heat is a measure of molecular energy; the total amount of heat depends upon the number of molecules, dictated by the mass of the object. Consider, for example, a reaction that produces a gas, such as dissolving a piece of copper in concentrated nitric acid. Peter J. Mikulecky, PhD, teaches biology and chemistry at Fusion Learning Center and Fusion Academy. The enthalpy of a system is defined as the sum of its internal energy \(U\) plus the product of its pressure \(P\) and volume \(V\): Because internal energy, pressure, and volume are all state functions, enthalpy is also a state function. It is the change in internal energy that produces heat plus work. ","hasArticle":false,"_links":{"self":"https://dummies-api.dummies.com/v2/authors/9160"}}],"primaryCategoryTaxonomy":{"categoryId":33762,"title":"Chemistry","slug":"chemistry","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33762"}},"secondaryCategoryTaxonomy":{"categoryId":0,"title":null,"slug":null,"_links":null},"tertiaryCategoryTaxonomy":{"categoryId":0,"title":null,"slug":null,"_links":null},"trendingArticles":null,"inThisArticle":[],"relatedArticles":{"fromBook":[{"articleId":208625,"title":"Chemistry For Dummies Cheat Sheet","slug":"chemistry-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","chemistry"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/208625"}}],"fromCategory":[{"articleId":253707,"title":"How to Make Unit Conversions","slug":"make-unit-conversions","categoryList":["academics-the-arts","science","chemistry"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/253707"}},{"articleId":251836,"title":"How to Convert between Units Using Conversion Factors","slug":"convert-units-using-conversion-factors","categoryList":["academics-the-arts","science","chemistry"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/251836"}},{"articleId":251010,"title":"How to Build Derived Units from Base Units","slug":"build-derived-units-base-units","categoryList":["academics-the-arts","science","chemistry"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/251010"}},{"articleId":251005,"title":"How to Do Arithmetic with Significant Figures","slug":"arithmetic-significant-figures","categoryList":["academics-the-arts","science","chemistry"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/251005"}},{"articleId":250992,"title":"How to Add and Subtract with Exponential Notation","slug":"add-subtract-exponential-notation","categoryList":["academics-the-arts","science","chemistry"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/250992"}}]},"hasRelatedBookFromSearch":false,"relatedBook":{"bookId":287363,"slug":"chemistry-for-dummies","isbn":"9781119293460","categoryList":["academics-the-arts","science","chemistry"],"amazon":{"default":"https://www.amazon.com/gp/product/1119293464/ref=as_li_tl?ie=UTF8&tag=wiley01-20","ca":"https://www.amazon.ca/gp/product/1119293464/ref=as_li_tl?ie=UTF8&tag=wiley01-20","indigo_ca":"http://www.tkqlhce.com/click-9208661-13710633?url=https://www.chapters.indigo.ca/en-ca/books/product/1119293464-item.html&cjsku=978111945484","gb":"https://www.amazon.co.uk/gp/product/1119293464/ref=as_li_tl?ie=UTF8&tag=wiley01-20","de":"https://www.amazon.de/gp/product/1119293464/ref=as_li_tl?ie=UTF8&tag=wiley01-20"},"image":{"src":"https://www.dummies.com/wp-content/uploads/chemistry-for-dummies-2nd-edition-cover-9781119293460-203x255.jpg","width":203,"height":255},"title":"Chemistry For Dummies","testBankPinActivationLink":"","bookOutOfPrint":false,"authorsInfo":"John T. Moore, EdD, is regents professor of Chemistry at Stephen F. Austin State University, where he is also the director of the Teaching Excellence Center.
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