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b8a83502-368f-4f79-9ba2-e31bd0809436 Observations for the reaction of alkali metal with water: Summary  Piece of metal floats (alkali metals have low density).  Piece of metal darts around.  A hissing sound is heard due to the evolution of a gas.  If red litmus paper is dipped in the solution, the paper turns blue due to the formation of the alkali metal hydroxide.  If few drops of phenolphthalein indicator are added to the water solution turns pink due to the formation of alkali metal hydroxide.  If the gas produced is tested with a lit splint, it burns with a squeaky pop sound.

92f26f48-6328-4d02-b3d9-3df42efe8753 Elements in one column have similar chemical properties. Summary

0b104a9a-7852-4c4d-aa2c-04e2fe23b8e1 Given the heats of formation calculate the heat of reaction (simple application) Summary Given the heats of formation calculate the heat of reaction (simple application) Given: C(diamond) + O2(g) → CO2(g) ΔH = −395.4 kJ C(graphite) + O2(g) → CO2(g) ΔH = −393.5 kJ a) Find ΔH for the manufacture of diamond from graphite: C(graphite) → C(diamond) H = -393.5 + 395.4 = + 1.9 kJ b) Is heat absorbed or evolved as graphite is converted to diamond? Absorbed When given the heats of formation, we can calculate the heat of reaction for a specific process by applying the concept of Hess's law. Hess's law states that the overall heat of a reaction is independent of the pathway taken. This allows us to use known heats of formation to determine the heat of reaction for a desired process. Let's consider the given example of the reaction between graphite (C(graphite)) and oxygen gas (O2) to form carbon dioxide (CO2): C(graphite) + O2(g) → CO2(g) ΔH = -393.5 kJ To find the heat of reaction for the conversion of graphite to diamond, we need to compare the heats of formation of diamond (C(diamond)) and graphite (C(graphite)). By using the concept of Hess's law, we can subtract the heat of formation of graphite from the heat of formation of diamond. a) Find ΔH for the manufacture of diamond from graphite: C(graphite) → C(diamond) ΔH = -393.5 kJ + 395.4 kJ = +1.9 kJ By adding the heats of formation of the reactants and products, we find that the heat of reaction for the manufacture of diamond from graphite is +1.9 kJ. This positive value indicates that heat is absorbed during the conversion process, as the energy required to form the diamond is greater than the energy released during the formation of graphite. b) Is heat absorbed or evolved as graphite is converted to diamond? Heat is absorbed. Based on the positive value of ΔH (+1.9 kJ) for the conversion of graphite to diamond, we can conclude that heat is absorbed during this process. This means that energy is taken in from the surroundings to convert graphite into diamond. To summarize, when given the heats of formation, we can calculate the heat of reaction by applying Hess's law. In the example provided, we determined the heat of reaction for the conversion of graphite to diamond by subtracting the heats of formation of the reactants and products. The positive value of ΔH indicates that heat is absorbed during this process, indicating an energy input required for the conversion. Understanding this concept helps us analyze the energy changes and transformations that occur during chemical reactions.

3d0f7ff3-44b6-437e-a2fe-402ed975995a Stoichiometric Calculations Summary These calculations involve using the coefficients from a balanced chemical equation to calculate the amounts of reactants or products involved in the reaction.

0680d4fb-a194-4c18-b4f1-2e7387586c8d Exothermic Reaction Summary Is a reaction which releases heat to the surrounding. As heat is released, the temperature of the surrounding increases. Cooling a substance, freezing, condensation are examples of exothermic processes

80bcae78-2071-43b4-96d0-fd8ac4a28430 The Maxwell-Boltzman curve can be used to explain the effect of temperature on reaction rates. Summary

535747cc-4a12-4946-8602-234cd0bca792 Solving Problems Summary To determine the energy released or required

< Back Reaction kinetics Previous Next 🔬 Chapter 9: Rates of Reaction 🔬 Learning Outcomes 🎯: Understand reaction kinetics and the factors affecting the rates of chemical reactions. Recognize the role of surface area, concentration, temperature, and catalysts in reaction rates. Understand the concept of activation energy and its role in determining the rate of reaction. Differentiate between homogeneous and heterogeneous catalysts. Understand the Boltzmann distribution of molecular energies and how it changes with temperature. Factors Affecting Rate of Reaction 📈: Surface Area : Finely divided solids have a larger surface area, leading to more frequent collisions and a faster reaction rate. Concentration and Pressure : Higher concentration or pressure leads to more frequent collisions between reactant molecules, increasing the reaction rate. Temperature : At higher temperatures, molecules have more kinetic energy, leading to more frequent and successful collisions. Catalysts : Catalysts increase the rate of reaction by providing an alternative reaction pathway with a lower activation energy. Activation Energy ⚡: Activation energy is the minimum energy required by colliding particles for a reaction to occur. It acts as a barrier to reaction, and only particles with energy greater than the activation energy can react. Boltzmann Distribution 📊: The Boltzmann distribution represents the number of molecules in a sample with particular energies. At higher temperatures, the distribution changes, showing that more molecules have energy greater than the activation energy, leading to an increase in reaction rate. Catalysis 🧪: Catalysts lower the activation energy, allowing a greater proportion of molecules to have sufficient energy to react. Homogeneous catalysts are in the same phase as the reactants, while heterogeneous catalysts are in a different phase. Enzymes are biological catalysts that provide an alternative reaction pathway of lower activation energy.

94b25da5-79f4-4454-a3cd-3b49473275b2 8. Any reaction or process that releases heat energy Exothermic Summary

efd481a4-b0ce-48ea-aaa8-890c788a5151 dm³ Summary A unit of volume equal to one cubic decimeter, equivalent to 1 liter.

04ce2f71-3e30-4a65-b7a6-d360c2a2add9 < Back Previous Next Stoichiometry Next Topic

8ab8f71e-1a76-468f-9332-0a283163e5ec Find heat involved with given mass of reactant/product from H Summary Finding the heat involved with a given mass of reactant or product from ΔH (enthalpy change) is an important aspect of thermochemistry. It allows us to determine the amount of heat transferred during a chemical reaction, based on the known enthalpy change and the mass of the reactant or product. The heat involved (q) can be calculated using the equation q = ΔH * m, where q represents the heat involved, ΔH is the enthalpy change, and m is the mass of the reactant or product. To use this equation, we need to know the value of ΔH, which can be obtained from experimental data or calculated using thermochemical equations. Additionally, we need to know the mass (m) of the reactant or product involved in the reaction. For example, let's consider the combustion of methane (CH4), where the enthalpy change (ΔH) is known to be -890 kJ/mol. If we have 10 grams of methane, we can calculate the heat involved as follows: q = ΔH * m = -890 kJ/mol * (10 g / 16 g/mol) = -556.25 kJ Therefore, in this case, the heat involved with 10 grams of methane in the combustion reaction is approximately -556.25 kJ. It's important to note that the sign of the enthalpy change (ΔH) indicates the direction of heat transfer. A negative ΔH value represents an exothermic reaction, where heat is released, while a positive ΔH value represents an endothermic reaction, where heat is absorbed. It's crucial to ensure that the units of enthalpy change (ΔH) and mass (m) are consistent in the calculation. If the enthalpy change is given in kilojoules per mole (kJ/mol), the mass should be in moles as well. By using the equation q = ΔH * m, we can determine the heat involved with a given mass of reactant or product in a reaction. This calculation allows us to understand the energy changes associated with chemical reactions and provides valuable insights into the heat flow within a system. In summary, finding the heat involved with a given mass of reactant or product involves using the equation q = ΔH * m, where q represents the heat involved, ΔH is the enthalpy change, and m is the mass of the reactant or product. By multiplying the enthalpy change by the mass, we can calculate the amount of heat transferred. Understanding and calculating the heat involved are essential in studying and analyzing energy changes in chemical reactions.