Entropy Spontaneous Reactions: reactions that given the necessary Ea‚ proceed to completion without continuous assistance Enthalpy and Spontaneity * exothermic reactions tend to be spontaneous * Endothermic reactions can be either * Electrolysis of water is non-spontaneous it will stop if you stop the supply of energy * DD reaction between ammonium nitrate and barium hydroxide is spontaneous‚ even through the Entropy * Measure of disorder or randomness * Can apply to
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synthesis reactions‚ involve the combination of two or more substances into a single new substance: A + B ---> AB Many metal oxides‚ for example‚ absorb carbon dioxide (CO2) from the air to form carbonates: CaO(s) + CO2(g) ---> CaCO3(s) Decomposition Decomposition reactions represent the reverse of the combination process in that one substance breaks down into two or more substances: AB ---> A + B Water‚ or H2O‚ for example‚ decomposes into its constituent elements when subjected to an electric
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5.2.2 Enthalpy and Entropy For 2013-2014 S for melting vs. boiling Discuss How do chemists work out whether a reaction will happen or not? There are various ways including equilibrium constants‚ standard electrode potentials and enthalpy values. But how are these related? There is a more fundamental concept which links all these together. Remember? Enthalpy is a measure of heat energy and ΔH is the enthalpy change which we studied at AS. Questions 1. Which sign for ΔH would
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Guess Paper – 2009 Class – X Subject – Chemistry (P- Block Elements) Kalra sir 09460472649 kalra1977@rediffmail.com Group 15 elements: |Symbol |Atomic |Electronic configuration | | |number | | | |7 |[He]2s22p3 | |N | | | |P |15 |[Ne] 3s23p3 | |As |33 |[Ar]3d104s24p3
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Joshua McMahon IB Chemistry Matt Chase 3A 11/5/14 Finding the Molar Enthalpy Change of sodium bicarbonate by using Hess Law Research Question By using Hess’ Law‚ can the Molar Enthalpy Change of sodium bicarbonate be calculated? Hypothesis If we are attempting to determine the enthalpy change of the thermal decomposition of Sodium Bicarbonate‚ then Hess’s Law will be will be the most effective. Introduction Sodium bicarbonate‚ more commonly known as baking soda‚ has many uses in todays
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particle. * Enthalpy Change (ΔH) is the heat energy transferred in a reaction at constant pressure. The units of ΔH are in kJ mol-1. All chemical reactions have enthalpy changes. * The reactions can be exothermic or endothermic. Exothermic reactions give out energy‚ and thus the ΔH is negative. Endothermic reactions absorb energy‚ thus ΔH is positive. Combustion is exothermic and thermal decomposition is endothermic. * Enthalpy changes can be calculated using average bond enthalpies. To break
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property that characterizes the process. It is easily measured‚ and if the process is a chemical reaction carried out at constant pressure‚ it can also be predicted from the difference between the enthalpies of the products and reactants. The quantitative study and measurement of heat and enthalpy changes is known as thermochemistry. 1 Thermochemical equations and standard states In order to define the thermochemical properties of a process‚ it is first necessary to write a thermochemical
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do the worksheet without referring to them‚ because you’ll be expected to know this stuff the first day of school! Balance the following equations: 1) ___ N2 + ___ F2 ( ___ NF3 2) ___ C6H10 + ___ O2 ( ___ CO2 + ___ H2O 3) ___ HBr + ___ KHCO3 ( ___ H2O + ___ KBr + ___ CO2 4) ___ GaBr3 + ___ Na2SO3 ( ___ Ga2(SO3)3 + ___ NaBr 5) ___ SnO + ___ NF3 ( ___ SnF2 + ___ N2O3 Using the equation from problem 2 above‚ answer the following questions: 6) If I do this reaction with 35 grams
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SYLLABUS – ADVANCED PLACEMENT CHEMISTRY Required Texts 1. Chemistry: The Central Science by Brown‚ LeMay and Bursten‚ 10th ed.‚ Pearson Education. Inc.‚ Upper Saddle River‚ NJ‚ 2006‚ ISBN: 0131464892 Includes: Text book‚ Laboratory Manual‚ Student Study Guide‚ AP Test Prep Series‚ Solutions to Practice Problems 2. Barrons AP Chemistry‚ Jespersen‚ Neil D‚ 4th ed.‚ Barron’s Educational Series‚ Inc‚ 250 Wireless Boulevard‚ Hauppauge‚ New York 11788
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important safety feature in vehicles. Sodium azide‚ potassium nitrate and silicon dioxide have been used in one design of airbag. [Source: www.hilalairbag.net] Sodium azide‚ a toxic compound‚ undergoes the following decomposition reaction under certain conditions. 2NaN 3 (s) → 2Na (s) + 3N 2 (g) Two students looked at data in a simulated computer-based experiment to determine the volume of nitrogen generated in an airbag. (a) Sodium azide involves ionic bonding
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