Thermochemistry Thermochemistry is the study of heat evolved and absorbed during the chemical reactions. The system is the interest of the universe; the surroundings are the rest of the universe in which the exchange of the energy with the system takes place. Both‚ the system and the surroundings make up the universe. Heat flow is the transfer of heat from a warm place to a cooler one. System to surroundings: Surroundings to system:
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imagine an endothermic reaction (heat is on the reactants side where the solid is). Increasing the temperature would result in stress on the reactants side from the additional heat. Le Châtelier’s Principle predicts that the system would shift towards the product’s side in order to alleviate this stress. By shifting towards the product’s side‚ more of the solid is dissociated when equilibrium is again established - which equates to increased solubility. Second‚ imagine an exothermic reaction (heat is
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is being released or absorbed in a chemical reaction. My lab partner and I had to determine the heat exchanged when solid magnesium hydroxide is mixed with solid citric acid‚ using a coffee cup calorimeter. Given that citric acid is soluble in water is the property that makes this reaction possible. The first law of thermodynamics and Hess’s law are also present within this experiment. Knowing the difference between endothermic and exothermic reactions is also relevant. If the temperature goes down
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In the lab testing the heat of a reaction to understand changes in enthalpy in an exothermic reaction‚ the group hypothesized that if the amount of reactant is changed then the amount of heat produced (exothermic) will increase. This hypothesis was supported through the data as each of the six trials produced heat and the larger the piece of magnesium the larger the change in heat was. In the first trial the group had .085 grams of Mg and after being placed in 3 ml of 21.8℃ HCl the temperature of
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* . Introduction Endothermic reactions are accompanied by the absorption of heat. The dissolving of ammonium nitrate in water is an example of an endothermic reaction. The solution resulting from this mixture is colder than either the ammonium nitrate or the water. This is the simple explanation of what happens in an instant ice pack. The more detailed information will be discussed in the following paragraphs. Cold Packs Most cold packs come with a fabric cover made to absorb condensation and
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Endothermic Reactions of Cold Packs An instant cold pack is a device that is made up of two bags; one containing water‚ and an inside bag containing ammonium nitrate. Have you ever wondered how people use hot packs to warm up their hands in the winter or use cold packs on a real terrible injury? How can this package produce heat or cold by only shaking or crushing those packs? Ammonium nitrate is a chemical compound that is a white crystalline solid used as fertilizer and as a part of explosives
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All chemical reactions are processed through energy exchanges. Chemical reactions either absorb energy or release energy into their surroundings. In thermodynamics‚ endothermic reactions absorb energy where exothermic reactions release energy. In this experiment‚ we will be observing the chemical reactions that occur when a specific liquid is combined with a specific solid. We will measure the temperature of the liquid before the solid is added. Then we will measure the temperature of the liquid
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EXPERIMENT # 14: Exothermic and endothermic reactions Date: 25/06/2012 Name: Meagen Reyes Year 11 PARTS A‚ B and C * For the procedures and equipment needed in these experiments‚ refer to page 73-74 in the STAWA Exploring chemistry stage 2 book Part A: solution process (dissociation) Solutions and their chemical equations | Initial temperature (in Celsius) | Final temperature (in Celsius) | Classification(exothermic or endothermic) | Sodium hydroxide NaOH(s) Na+(aq) + OH-(aq) + Energy
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Introduction – Lab Report What is a Chemical Reaction? A chemical reaction is a change in matter that produces one or more new substances. A chemical change or reaction occurs when bonds are broken and new ones are formed. The formation and dissolution of these bonds are dependent upon environment changes. Even without the usage of microscopes‚ chemical reactions are usually apparent to the naked eye. The two main kinds of changes that one can observe are the formation of new substances and changes
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From the results recorded it was identified that activity A and C had exothermic reactions‚ whilst activity B had an endothermic reaction. Each of the activities had initially begun with 23.4/8/9oC‚ however‚ within one minute of adding the 2nd reactants‚ the results began showing‚ as seen from the graph. Activity A and C had risen in temperature‚ with A gaining 4oC and in total of 2 minutes having the temperature of 27.9oC along with C increasing by 2.2oC and within 2 minutes of the experiment having
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