The APsolute RecAP: Chemistry Edition - Enthalpy
01/18/21 • 10 min
Heat, Energy and now Enthalpy? What is going on? Our episode starts by defining and distinguishing between these concepts (0:54) before taking a closer look at enthalpy itself. The episode connects the mathematical sign of enthalpy to the heat being absorbed / released (1:39) and discusses the extensive character of enthalpy (2:06) as well the value of reversed reactions (2:23) and its dependency on the state (2:47). We also recap two approaches to calculate the enthalpy of a reaction: taking into account the bonds broken and bonds formed (3:06) as well as the standard enthalpies of formation (5:25). To clarify the calculations using the standard enthalpies of formation, we discuss the combustion of propane (7:10).
Question (9:20): What is the law called that allows us to use the sum of enthalpy changes, independent of the steps?
Thank you for listening to The APsolute RecAP: Chemistry Edition!
(AP is a registered trademark of the College Board and is not affiliated with The APsolute RecAP. Copyright 2021 - The APsolute RecAP, LLC. All rights reserved.)
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Heat, Energy and now Enthalpy? What is going on? Our episode starts by defining and distinguishing between these concepts (0:54) before taking a closer look at enthalpy itself. The episode connects the mathematical sign of enthalpy to the heat being absorbed / released (1:39) and discusses the extensive character of enthalpy (2:06) as well the value of reversed reactions (2:23) and its dependency on the state (2:47). We also recap two approaches to calculate the enthalpy of a reaction: taking into account the bonds broken and bonds formed (3:06) as well as the standard enthalpies of formation (5:25). To clarify the calculations using the standard enthalpies of formation, we discuss the combustion of propane (7:10).
Question (9:20): What is the law called that allows us to use the sum of enthalpy changes, independent of the steps?
Thank you for listening to The APsolute RecAP: Chemistry Edition!
(AP is a registered trademark of the College Board and is not affiliated with The APsolute RecAP. Copyright 2021 - The APsolute RecAP, LLC. All rights reserved.)
Website:
EMAIL:
Follow Us:
Previous Episode
The APsolute RecAP: Chemistry Edition - Heat Capacity and Calorimetry
Heat transfer is all around! The episode starts by describing the heat transfer on a particle level (0:58). Heat transferred can be quantified using the heat transfer equation (1:42). The heat transfer equation takes into account the mass of the substance (2:32), the specific heat capacity (4:12) as well as the change in temperature (6:05). It can be measured in an experimental set up by using calorimetry (6:18).
Question (8:01): What is the molar heat capacity of water in J/mol K?
Thank you for listening to The APsolute RecAP: Chemistry Edition!
(AP is a registered trademark of the College Board and is not affiliated with The APsolute RecAP. Copyright 2020 - The APsolute RecAP, LLC. All rights reserved.)
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Next Episode
The APsolute RecAP: Chemistry Edition - Equilibrium Constant
Try to keep your balance! The episode starts with an analogy of villagers commuting from Moleville to Chemtown (0:59). Tying it to a chemical reaction, we define equilibrium as the point where the rate of the forward and the rate of the reverse reaction are the same (1:43). To determine if, at equilibrium, a reaction has more reactants or products, we can calculate the equilibrium constant, capital K (3:59) and write the equilibrium expression (4:34). The magnitude of K tells us if a reaction favors the products or the reactants (5:35). To determine if a reaction is at equilibrium, we can calculate Q (6:12).
Question (8:14): The equilibrium constant for a known reaction is K = 150. What would the value for K’ be if you’d reverse the reaction at the same temperature?
Thank you for listening to The APsolute RecAP: Chemistry Edition!
(AP is a registered trademark of the College Board and is not affiliated with The APsolute RecAP. Copyright 2021 - The APsolute RecAP, LLC. All rights reserved.)
Website:
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