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Energetics

A-Level AQA Chemistry

This flashcard pack provides a comprehensive overview of thermodynamics and enthalpy changes, detailing concepts like exothermic and endothermic reactions, standard enthalpy changes of formation and combustion, calorimetry, Hess's law, mean bond energies, and calculations involving enthalpy changes for various chemical reactions.

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"Define mean bond energy."	"Mean bond energy is the average energy required to break a covalent bond into gaseous atoms, averaged over different molecules."
"What are Hess's law cycles used for?"	"Hess's law cycles are used to measure the enthalpy change for a reaction that cannot be measured directly by experiments. Instead, alternative reactions are carried out that can be measured experimentally."
"How is Hess's law used to determine the enthalpy change for forming a hydrated salt from an anhydrous salt?"	"Hess's law is used to work out the enthalpy change to form a hydrated salt from an anhydrous salt by using a series of reactions and their corresponding enthalpy changes."
"Describe Hess's law."	"Hess's law is a principle in thermodynamics that states that the enthalpy change of a reaction is independent of the pathway taken to reach the final products, as long as the initial and final conditions are the same."
"What is the formula for calculating the enthalpy change of a reaction using Hess's law?"	"The formula is AH reaction = H products - H reactants."
"Define enthalpy of formation."	"Enthalpy of formation is the enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states."
"How can you calculate the enthalpy change of a reaction using enthalpy of formation values?"	"You can calculate it by subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products."
"Describe the process of using Hess's law to determine enthalpy changes from enthalpy changes of combustion."	"To determine enthalpy changes from enthalpy changes of combustion, you need to use the enthalpy changes of combustion of the reactants and products and apply the principle of Hess's law to calculate the enthalpy change of the reaction."
"Describe the enthalpy of formation of propene."	"The enthalpy of formation of propene is the energy change when one mole of propene is formed from its constituent elements in their standard states."
"How are mean bond energies used in calculations?"	"Mean bond energies are used to estimate the enthalpy change in reactions by subtracting the sum of bond energies broken from the sum of bond energies made."
"Describe the difference between an exothermic and endothermic reaction."	"In an exothermic reaction, the energy released by forming new bonds is greater than the energy required to break existing bonds. In an endothermic reaction, the energy required to break existing bonds is greater than the energy released by forming new bonds."
"Describe how to calculate the enthalpy of combustion of propene using bond enthalpy data."	"The enthalpy of combustion of propene can be calculated by subtracting the sum of bond energies made from the sum of bond energies broken."
"How can the enthalpy of formation of NH3 be calculated using bond enthalpy data?"	"The enthalpy of formation of NH3 can be calculated by subtracting the sum of bond energies made from the sum of bond energies broken."
"Describe the process of calculating the enthalpy of a compound using bond enthalpies and other data."	"To calculate the enthalpy of a compound, bond enthalpies and other data such as atomisation energies or standard enthalpies of formation can be used. The bond energies of the bonds broken are subtracted from the bond energies of the bonds formed."
"Describe how to calculate the enthalpy of propane, C3H8(g), using bond enthalpy data."	"To calculate the enthalpy of propane, the sum of the bond energies of the bonds formed is subtracted from the sum of the bond energies of the bonds broken."
"Describe the trend in enthalpies of combustion for successive members of a homologous series."	"There is a constant rise in the size of the enthalpies of combustion as the number of carbon atoms increases."
"What type of bonds are broken during the combustion of alkanes or alcohols?"	"C-C, C-H, and O=O bonds are broken."
"How many C=O and O-H bonds are made during the combustion of ethanol?"	"4 C=O and 6 O-H bonds are made."
"Define incomplete combustion."	"It is a type of combustion where there is not enough oxygen present to completely oxidize the fuel, resulting in less energy being released and the formation of products like carbon monoxide (CO) or soot."
"What assumption is made about the heat capacity of water in reactions where the reactants are dissolved in water?"	"The assumption is that the heat capacity is the same as pure water."
"Describe an exothermic change."	"In an exothermic change, energy is transferred from the system (chemicals) to the surroundings."
"What is the standard enthalpy change of formation?"	"The standard enthalpy change of formation of a compound is the enthalpy change when 1 mole of the compound is formed from its elements under standard conditions (298K and 100kPa), all reactants and products being in their standard states."
"Describe the standard enthalpy change of combustion."	"The standard enthalpy of combustion of a substance is defined as the enthalpy change that occurs when one mole of a substance is combusted completely in oxygen under standard conditions (298K and 100kPa), all reactants and products being in their standard states."
"What is the equation used to calculate the energy change for a reaction in solution?"	"energy change = mass of solution X heat capacity X temperature change"
"Describe the general method for measuring the enthalpy change for a reaction experimentally."	"Mix substances in an insulated container, measure temperature rise"
"What are some errors in the calorimetric method of measuring enthalpy change?"	"Energy transfer from surroundings, approximation in specific heat capacity of solution, neglecting specific heat capacity of calorimeter"
"How can the temperature curve be extrapolated back to the time the reactants were added together?"	"By taking readings at regular time intervals and extrapolating the temperature curve/line"
"What is the purpose of using an insulated cup in the calorimetric method?"	"To minimize heat loss to the surroundings"
"Describe the general method for calculating the enthalpy change of reaction from experimental data."	"Using the equation Q = mcΔT, calculate the energy change for the quantities used. Then, work out the moles of the reactants used and divide Q by the number of moles of the reactant not in excess to give AH. Finally, add a sign and unit to represent the energy change."
"Define enthalpy change."	"Enthalpy change is the amount of heat energy taken in or given out during any change in a system provided the pressure is constant."
"How do you calculate the energy change for the amount of reactants in the calorimeter?"	"Multiply the mass of the solution by the specific heat capacity of water and the change in temperature (Q = mcΔT)."
"Define enthalpy change of reaction."	"Enthalpy change of reaction is the energy change per mole of a reaction, often represented as AH."
"Describe how to determine the enthalpy change per mole of a reaction."	"Divide the energy change (Q) by the number of moles of the reactant not in excess (AH = Q/no of moles)."
"Describe how enthalpies of combustion can be calculated using calorimetry."	"Enthalpies of combustion can be calculated using calorimetry by burning the fuel and using the flame to heat up water in a metal cup."
"What is the purpose of using calorimetry in measuring enthalpies of combustion?"	"The purpose of using calorimetry is to measure the energy change produced by the combustion of a fuel."
"Define enthalpy change of combustion."	"Enthalpy change of combustion is the energy change that occurs when one mole of a substance is completely combusted."
"How can the energy change used to heat up water be calculated in calorimetry?"	"The energy change used to heat up water can be calculated by multiplying the mass of water, the specific heat capacity of water, and the change in temperature."
"Describe the steps involved in calculating the enthalpy change of combustion using calorimetry."	"The steps involved are: 1) Calculate the energy change used to heat up the water. 2) Calculate the number of moles of alcohol combusted. 3) Calculate the enthalpy change per mole. 4) Add in the sign to represent the energy change."

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Define mean bond energy.

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Mean bond energy is the average energy required to break a covalent bond into gaseous atoms, averaged over different molecules.

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[{"id":974731,"front":"Define mean bond energy.","back":"Mean bond energy is the average energy required to break a covalent bond into gaseous atoms, averaged over different molecules.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":0,"explanation":"Mean bond energy is a measure of the strength of a covalent bond. It represents the average amount of energy needed to break a bond and separate the bonded atoms into gaseous form. This value is calculated by averaging the bond energies of different molecules. It provides insight into the stability and strength of chemical bonds.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974705,"front":"What are Hess's law cycles used for?","back":"Hess's law cycles are used to measure the enthalpy change for a reaction that cannot be measured directly by experiments. Instead, alternative reactions are carried out that can be measured experimentally.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":1,"explanation":"Hess's law cycles are utilized when direct measurement of the enthalpy change for a reaction is not feasible. Instead, alternative reactions are conducted and their enthalpy changes are measured experimentally. By applying Hess's law, the enthalpy change for the desired reaction can be calculated based on the enthalpy changes of the alternative reactions. This allows for the determination of the enthalpy change of a reaction indirectly.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974706,"front":"How is Hess's law used to determine the enthalpy change for forming a hydrated salt from an anhydrous salt?","back":"Hess's law is used to work out the enthalpy change to form a hydrated salt from an anhydrous salt by using a series of reactions and their corresponding enthalpy changes.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":2,"explanation":"Hess's law is based on the principle that the overall enthalpy change of a reaction is independent of the pathway taken. By using a series of reactions with known enthalpy changes, the enthalpy change for forming a hydrated salt can be determined. This is done by manipulating the reactions and their enthalpy changes to cancel out intermediate species and obtain the desired reaction. The enthalpy change for the desired reaction can then be calculated by summing the enthalpy changes of the manipulated reactions.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974707,"front":"Describe Hess's law.","back":"Hess's law is a principle in thermodynamics that states that the enthalpy change of a reaction is independent of the pathway taken to reach the final products, as long as the initial and final conditions are the same.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":3,"explanation":"Hess's law is based on the concept of conservation of energy. It states that the total enthalpy change of a reaction is determined only by the initial and final states, regardless of the intermediate steps or pathways. This principle allows us to calculate the enthalpy change of a reaction by combining known enthalpy changes of other reactions. It is a useful tool in thermochemistry calculations and provides a way to determine the enthalpy change of reactions that cannot be directly measured.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974709,"front":"What is the formula for calculating the enthalpy change of a reaction using Hess's law?","back":"The formula is AH reaction = H products - H reactants.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":4,"explanation":"Hess's law states that the enthalpy change of a reaction is independent of the pathway taken. This means that the enthalpy change can be calculated by taking the difference between the enthalpies of the products and the enthalpies of the reactants. This formula allows for the determination of the enthalpy change of a reaction using known enthalpy values of other reactions.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974710,"front":"Define enthalpy of formation.","back":"Enthalpy of formation is the enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":5,"explanation":"Enthalpy of formation is a measure of the energy change that occurs when a compound is formed from its constituent elements. It is specifically defined as the enthalpy change for the formation of one mole of the compound from its elements in their standard states. This value is important in understanding the stability and energy content of a compound, and is commonly used in thermodynamic calculations and chemical reactions.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974714,"front":"How can you calculate the enthalpy change of a reaction using enthalpy of formation values?","back":"You can calculate it by subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":6,"explanation":"Enthalpy of formation values represent the energy change when one mole of a compound is formed from its constituent elements in their standard states. By subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products, you can determine the overall enthalpy change of the reaction. This is based on the principle that the enthalpy change of a reaction is equal to the difference in enthalpy between the products and reactants.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974720,"front":"Describe the process of using Hess's law to determine enthalpy changes from enthalpy changes of combustion.","back":"To determine enthalpy changes from enthalpy changes of combustion, you need to use the enthalpy changes of combustion of the reactants and products and apply the principle of Hess's law to calculate the enthalpy change of the reaction.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":7,"explanation":"Hess's law states that the overall enthalpy change of a reaction is independent of the pathway taken. By using enthalpy changes of combustion, which are readily measured, we can calculate the enthalpy change of a reaction indirectly. This is done by manipulating the given reactions and their enthalpy changes to cancel out common species and obtain the desired reaction. The enthalpy change of the desired reaction is then equal to the sum of the enthalpy changes of the manipulated reactions. This allows us to determine the enthalpy change of a reaction without directly measuring it.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974725,"front":"Describe the enthalpy of formation of propene.","back":"The enthalpy of formation of propene is the energy change when one mole of propene is formed from its constituent elements in their standard states.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":8,"explanation":"The enthalpy of formation of propene is a measure of the energy change that occurs when propene is formed from its constituent elements in their standard states. It provides information about the stability and energy content of propene. This value is important in understanding the thermodynamics of chemical reactions involving propene and can be used to calculate the heat released or absorbed during these reactions.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974734,"front":"How are mean bond energies used in calculations?","back":"Mean bond energies are used to estimate the enthalpy change in reactions by subtracting the sum of bond energies broken from the sum of bond energies made.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":11,"explanation":"Mean bond energies are used in calculations to estimate the enthalpy change in reactions. This is done by subtracting the sum of bond energies broken during the reaction from the sum of bond energies formed. This approach allows for a rough estimation of the energy changes involved in a reaction, providing valuable insight into the overall thermodynamics of the process.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974740,"front":"Describe the difference between an exothermic and endothermic reaction.","back":"In an exothermic reaction, the energy released by forming new bonds is greater than the energy required to break existing bonds. In an endothermic reaction, the energy required to break existing bonds is greater than the energy released by forming new bonds.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":12,"explanation":"In an exothermic reaction, more energy is released during the formation of new bonds than is required to break the existing bonds. This results in a net release of energy. In contrast, an endothermic reaction requires more energy to break the existing bonds than is released during the formation of new bonds. As a result, these reactions absorb energy from their surroundings.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974742,"front":"Describe how to calculate the enthalpy of combustion of propene using bond enthalpy data.","back":"The enthalpy of combustion of propene can be calculated by subtracting the sum of bond energies made from the sum of bond energies broken.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":13,"explanation":"To calculate the enthalpy of combustion of propene using bond enthalpy data, we need to consider the bonds broken and formed during the combustion reaction. Bond enthalpy is the energy required to break a bond or the energy released when a bond is formed. By subtracting the sum of bond energies formed from the sum of bond energies broken, we can determine the overall enthalpy change for the combustion reaction. This approach allows us to estimate the enthalpy of combustion based on the strength of the chemical bonds involved.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974745,"front":"How can the enthalpy of formation of NH3 be calculated using bond enthalpy data?","back":"The enthalpy of formation of NH3 can be calculated by subtracting the sum of bond energies made from the sum of bond energies broken.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":14,"explanation":"The enthalpy of formation of NH3 can be calculated using bond enthalpy data because it involves breaking and forming chemical bonds. By subtracting the sum of bond energies made from the sum of bond energies broken, we can determine the overall change in energy during the formation of NH3. This approach relies on the assumption that bond enthalpies are constant and independent of the molecular environment.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974748,"front":"Describe the process of calculating the enthalpy of a compound using bond enthalpies and other data.","back":"To calculate the enthalpy of a compound, bond enthalpies and other data such as atomisation energies or standard enthalpies of formation can be used. The bond energies of the bonds broken are subtracted from the bond energies of the bonds formed.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":15,"explanation":"Calculating enthalpy using bond enthalpies involves summing the energies needed to break bonds and subtracting the energies released when new bonds form. Additional data like atomization energies or standard enthalpies of formation can refine the calculation for accuracy.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974749,"front":"Describe how to calculate the enthalpy of propane, C3H8(g), using bond enthalpy data.","back":"To calculate the enthalpy of propane, the sum of the bond energies of the bonds formed is subtracted from the sum of the bond energies of the bonds broken.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":16,"explanation":"Calculating the enthalpy of propane involves considering the energy required to break the bonds in the reactants and the energy released when new bonds form in the products. This approach accounts for the overall change in energy during the chemical reaction, providing insight into the thermodynamics of the process.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974750,"front":"Describe the trend in enthalpies of combustion for successive members of a homologous series.","back":"There is a constant rise in the size of the enthalpies of combustion as the number of carbon atoms increases.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":17,"explanation":"The trend in enthalpies of combustion for successive members of a homologous series is due to the increase in the size and complexity of the molecules. As the number of carbon atoms increases, the molecular structure becomes more intricate, leading to higher enthalpies of combustion. This is a result of the increased energy required to break the stronger bonds and the larger number of carbon-hydrogen bonds present in the larger molecules.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974751,"front":"What type of bonds are broken during the combustion of alkanes or alcohols?","back":"C-C, C-H, and O=O bonds are broken.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":18,"explanation":"During the combustion of alkanes or alcohols, C-C, C-H, and O=O bonds are broken. This is because these bonds store energy, which is released as heat during combustion. Breaking these bonds allows the release of energy for various applications.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974752,"front":"How many C=O and O-H bonds are made during the combustion of ethanol?","back":"4 C=O and 6 O-H bonds are made.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":19,"explanation":"During the combustion of ethanol, each ethanol molecule (C2H5OH) is oxidized to produce carbon dioxide (CO2) and water (H2O). In the process, the carbon atom in ethanol forms four C=O bonds with oxygen atoms from the carbon dioxide molecules. Additionally, the oxygen atom in ethanol forms two O-H bonds with hydrogen atoms from the water molecules. Therefore, a total of four C=O bonds and six O-H bonds are made during the combustion of ethanol.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974753,"front":"Define incomplete combustion.","back":"It is a type of combustion where there is not enough oxygen present to completely oxidize the fuel, resulting in less energy being released and the formation of products like carbon monoxide (CO) or soot.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":20,"explanation":"Incomplete combustion occurs when fuel burns without sufficient oxygen, leading to the production of harmful byproducts like carbon monoxide and soot. This process is inefficient, resulting in less energy release compared to complete combustion.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974693,"front":"What assumption is made about the heat capacity of water in reactions where the reactants are dissolved in water?","back":"The assumption is that the heat capacity is the same as pure water.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":21,"explanation":"In reactions where reactants are dissolved in water, it is assumed that the heat capacity of water remains constant and is equivalent to that of pure water. This assumption is made because the heat capacity of water is relatively high and does not significantly change when solutes are added. Therefore, it is convenient to assume that the heat capacity of the solution is the same as that of pure water for simplicity in calculations and experimental analysis.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974683,"front":"Describe an exothermic change.","back":"In an exothermic change, energy is transferred from the system (chemicals) to the surroundings.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":22,"explanation":"Exothermic changes release energy to the surroundings, often in the form of heat. This occurs as the reactants have higher energy than the products, resulting in a net release of energy. This can be observed in various chemical reactions and processes, such as combustion and neutralization.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974685,"front":"What is the standard enthalpy change of formation?","back":"The standard enthalpy change of formation of a compound is the enthalpy change when 1 mole of the compound is formed from its elements under standard conditions (298K and 100kPa), all reactants and products being in their standard states.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":24,"explanation":"The standard enthalpy change of formation is a measure of the energy released or absorbed when a compound is formed from its elements. It is determined by the difference in energy between the reactants and products, with all substances in their standard states. This value is useful in calculating the heat of reactions and understanding the stability of compounds.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974686,"front":"Describe the standard enthalpy change of combustion.","back":"The standard enthalpy of combustion of a substance is defined as the enthalpy change that occurs when one mole of a substance is combusted completely in oxygen under standard conditions (298K and 100kPa), all reactants and products being in their standard states.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":25,"explanation":"The standard enthalpy change of combustion is a measure of the heat energy released or absorbed when one mole of a substance undergoes complete combustion in oxygen. It is determined under specific conditions of temperature and pressure, with all reactants and products in their standard states. This value provides important information about the energy content and efficiency of a substance as a fuel.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974687,"front":"What is the equation used to calculate the energy change for a reaction in solution?","back":"energy change = mass of solution X heat capacity X temperature change","front_language":"English","back_language":"English","front_image":"","back_image":"","order":26,"explanation":"The equation provided calculates the energy change for a reaction in solution. It takes into account the mass of the solution, the heat capacity of the solution, and the temperature change. The mass of the solution represents the amount of substance involved, while the heat capacity accounts for the ability of the solution to absorb or release heat. The temperature change indicates the difference in temperature before and after the reaction. By multiplying these factors together, the equation quantifies the energy change for the reaction in solution.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974688,"front":"Describe the general method for measuring the enthalpy change for a reaction experimentally.","back":"Mix substances in an insulated container, measure temperature rise","front_language":"English","back_language":"English","front_image":"","back_image":"","order":27,"explanation":"The general method for measuring the enthalpy change for a reaction experimentally involves mixing substances in an insulated container and measuring the temperature rise. This is because the enthalpy change of a reaction is related to the heat released or absorbed, which can be determined by monitoring the change in temperature. By using an insulated container, heat exchange with the surroundings is minimized, allowing for a more accurate measurement of the enthalpy change.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974689,"front":"What are some errors in the calorimetric method of measuring enthalpy change?","back":"Energy transfer from surroundings, approximation in specific heat capacity of solution, neglecting specific heat capacity of calorimeter","front_language":"English","back_language":"English","front_image":"","back_image":"","order":28,"explanation":"The calorimetric method of measuring enthalpy change can have errors due to energy transfer from the surroundings, which can affect the accuracy of the measurement. Another source of error is the approximation in the specific heat capacity of the solution being studied, as this can lead to inaccuracies in the calculated enthalpy change. Additionally, neglecting the specific heat capacity of the calorimeter itself can introduce errors in the measurement. These factors should be considered when using the calorimetric method to ensure accurate results.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974690,"front":"How can the temperature curve be extrapolated back to the time the reactants were added together?","back":"By taking readings at regular time intervals and extrapolating the temperature curve/line","front_language":"English","back_language":"English","front_image":"","back_image":"","order":29,"explanation":"The temperature curve can be extrapolated back to the time the reactants were added together by using regular time interval readings. By plotting these readings on a graph and extrapolating the temperature curve or line, it is possible to estimate the temperature at the time the reactants were mixed. This extrapolation technique allows for the estimation of the initial temperature of the reaction.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974691,"front":"What is the purpose of using an insulated cup in the calorimetric method?","back":"To minimize heat loss to the surroundings","front_language":"English","back_language":"English","front_image":"","back_image":"","order":30,"explanation":"Using an insulated cup in the calorimetric method helps to minimize heat loss to the surroundings. This is important because heat loss can lead to inaccurate measurements and affect the reliability of the experiment. Insulation helps to maintain a constant temperature within the cup, allowing for more precise and accurate calorimetric measurements.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974692,"front":"Describe the general method for calculating the enthalpy change of reaction from experimental data.","back":"Using the equation Q = mcΔT, calculate the energy change for the quantities used. Then, work out the moles of the reactants used and divide Q by the number of moles of the reactant not in excess to give AH. Finally, add a sign and unit to represent the energy change.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":31,"explanation":"The method provided outlines the steps for calculating the enthalpy change of a reaction using experimental data. It involves calculating the energy change using the equation Q = mcΔT, determining the moles of reactants, dividing Q by the moles of the reactant not in excess to obtain ΔH, and then representing the energy change with a sign and unit. This process allows for the determination of the enthalpy change based on experimental measurements.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974682,"front":"Define enthalpy change.","back":"Enthalpy change is the amount of heat energy taken in or given out during any change in a system provided the pressure is constant.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":32,"explanation":"Enthalpy change is a measure of the heat energy involved in a system's transformation, assuming constant pressure. It accounts for both heat absorbed and released during a process. This concept is crucial in understanding the energy flow in chemical reactions and physical changes. By quantifying the enthalpy change, scientists can analyze and predict the heat effects of various processes.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974694,"front":"How do you calculate the energy change for the amount of reactants in the calorimeter?","back":"Multiply the mass of the solution by the specific heat capacity of water and the change in temperature (Q = mcΔT).","front_language":"English","back_language":"English","front_image":"","back_image":"","order":33,"explanation":"Calculating the energy change in a calorimeter involves multiplying the mass of the solution by the specific heat capacity of water and the change in temperature. This formula, Q = mcΔT, accounts for the heat absorbed or released during a chemical reaction, providing insight into the reaction's energy dynamics.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974695,"front":"Define enthalpy change of reaction.","back":"Enthalpy change of reaction is the energy change per mole of a reaction, often represented as AH.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":34,"explanation":"Enthalpy change of reaction, denoted as ΔH, quantifies heat energy exchanged during a chemical reaction at constant pressure. It reflects the difference in enthalpy between products and reactants, aiding in determining reaction spontaneity and energy requirements.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974696,"front":"Describe how to determine the enthalpy change per mole of a reaction.","back":"Divide the energy change (Q) by the number of moles of the reactant not in excess (AH = Q/no of moles).","front_language":"English","back_language":"English","front_image":"","back_image":"","order":35,"explanation":"To determine the enthalpy change per mole of a reaction, you need to divide the energy change (Q) by the number of moles of the reactant not in excess. This is because enthalpy change is a measure of the heat energy released or absorbed during a reaction, and dividing it by the number of moles gives the enthalpy change per mole. This calculation allows for a comparison of the energy change on a per mole basis, which is useful for understanding the efficiency and scale of a reaction.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974697,"front":"Describe how enthalpies of combustion can be calculated using calorimetry.","back":"Enthalpies of combustion can be calculated using calorimetry by burning the fuel and using the flame to heat up water in a metal cup.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":36,"explanation":"Calorimetry measures heat changes in a reaction. By burning a fuel in a controlled environment and using the heat to raise the temperature of water, the enthalpy of combustion can be calculated. This method allows for the precise determination of the energy released during combustion.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974698,"front":"What is the purpose of using calorimetry in measuring enthalpies of combustion?","back":"The purpose of using calorimetry is to measure the energy change produced by the combustion of a fuel.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":37,"explanation":"Calorimetry is crucial for determining enthalpies of combustion as it allows for precise measurement of the heat released during a combustion reaction. This method helps in understanding the energy content of fuels and their efficiency in producing heat or energy.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974699,"front":"Define enthalpy change of combustion.","back":"Enthalpy change of combustion is the energy change that occurs when one mole of a substance is completely combusted.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":38,"explanation":"Enthalpy change of combustion is a crucial thermodynamic concept used to measure the energy released or absorbed during the complete combustion of a substance. It quantifies the heat exchange in a chemical reaction, providing valuable insights into the reaction's energy dynamics.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974700,"front":"How can the energy change used to heat up water be calculated in calorimetry?","back":"The energy change used to heat up water can be calculated by multiplying the mass of water, the specific heat capacity of water, and the change in temperature.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":39,"explanation":"In calorimetry, understanding the relationship between mass, specific heat capacity, and temperature change is crucial. This formula reflects how much energy is required to raise the temperature of a substance, highlighting the importance of specific heat in thermal processes and energy transfer.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}},{"id":974701,"front":"Describe the steps involved in calculating the enthalpy change of combustion using calorimetry.","back":"The steps involved are: 1) Calculate the energy change used to heat up the water. 2) Calculate the number of moles of alcohol combusted. 3) Calculate the enthalpy change per mole. 4) Add in the sign to represent the energy change.","front_language":"English","back_language":"English","front_image":"","back_image":"","order":40,"explanation":"The process involves determining the energy change to heat water, finding the moles of substance combusted, calculating enthalpy change per mole, and considering the sign for energy change. This allows for accurate enthalpy change of combustion using calorimetry.","deleted_at":null,"flashcard_deck_id":"9c1gO","original_id":null,"examMode":{"text":"","correct":"","incorrect":"","info":""}}]

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