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- https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%3A_Structure_and_Reactivity_in_Organic_Biological_and_Inorganic_Chemistry_(Schaller)/III%3A_Reactivity_in_Organic_Biological_and_Inorganic_Chemistry_1/01%3A_Thermodynamics/1.08%3A_Hess'_LawIf the heat of formation of tantalum(IV) oxide, TaO 2 , is -40 kcal/mol, and the heat of formation of tantalum(V) oxide, Ta 2 O 5 , is -490 kcal/mol, then what is the heat of reaction for the combusti...If the heat of formation of tantalum(IV) oxide, TaO 2 , is -40 kcal/mol, and the heat of formation of tantalum(V) oxide, Ta 2 O 5 , is -490 kcal/mol, then what is the heat of reaction for the combustion of TaO 2 to Ta 2 O 5 ? If the heat of formation of carbon monoxide, CO, is -25 kcal/mol and the heat of formation of tetracarbonyl nickel, Ni(CO) 4 , is -145 kcal/mol, then what is the heat of reaction for the formation of tetracarbonyl nickel from nickel and carbon monoxide?
- https://chem.libretexts.org/Bookshelves/General_Chemistry/General_Chemistry_Supplement_(Eames)/Thermochemistry/Hess'_Law_and_Enthalpy_of_FormationHess' Law lets us break a reaction or process into a series of small, easily measured steps, and then we can add up the ΔH of the steps to find the change in enthalpy of the whole thing. Make sure the...Hess' Law lets us break a reaction or process into a series of small, easily measured steps, and then we can add up the ΔH of the steps to find the change in enthalpy of the whole thing. Make sure the coefficients on equations are correct (multiply the equation and ΔH by a constant if needed) and that all the components are in the correct state (like the example above, we had to convert from liquid water to gaseous water).
- https://chem.libretexts.org/Bookshelves/General_Chemistry/Chem1_(Lower)/14%3A_Thermochemistry/14.04%3A_Thermochemistry_and_CalorimetryThe heat that flows across the boundaries of a system undergoing a change is a fundamental property that characterizes the process. It is easily measured, and if the process is a chemical reaction car...The heat that flows across the boundaries of a system undergoing a change is a fundamental 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.
- https://chem.libretexts.org/Ancillary_Materials/Laboratory_Experiments/Wet_Lab_Experiments/General_Chemistry_Labs/Online_Chemistry_Lab_Manual/Chem_11_Experiments/12%3A_Calorimetry_and_Hess's_Law_(Experiment)The combustion of a metal in oxygen produces the corresponding metal oxide as the only product. Such reactions are exothermic and release heat. Since it is difficult to measure the enthalpy of combust...The combustion of a metal in oxygen produces the corresponding metal oxide as the only product. Such reactions are exothermic and release heat. Since it is difficult to measure the enthalpy of combustion of a metal directly, in this lab it will be determined indirectly by applying Hess’s Law of Heat Summation. Hess’s Law states that the enthalpy change of an overall process is equal to the sum of the enthalpy changes of its individual steps.
- https://chem.libretexts.org/Bookshelves/General_Chemistry/Concept_Development_Studies_in_Chemistry_(Hutchinson)/10%3A_Energetics_of_Chemical_ReactionsThe heat released or consumed in a chemical reaction is typically amongst the most easily observed and most readily appreciated consequences of the reaction. Many chemical reactions are performed rout...The heat released or consumed in a chemical reaction is typically amongst the most easily observed and most readily appreciated consequences of the reaction. Many chemical reactions are performed routinely specifically for the purpose of utilizing the heat released by the reaction.
- https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%3A_Structure_and_Reactivity_in_Organic_Biological_and_Inorganic_Chemistry_(Schaller)/III%3A_Reactivity_in_Organic_Biological_and_Inorganic_Chemistry_1/01%3A_Thermodynamics/1.09%3A_Solutions_to_Selected_ProblemsThe removal of any item produced on the right side of the reaction will shift the reaction to the right in order to restore equilibrium. Another way of looking at things is that the external entropy c...The removal of any item produced on the right side of the reaction will shift the reaction to the right in order to restore equilibrium. Another way of looking at things is that the external entropy change is relatively small at high temperature, because the additional distribution of energy resulting from the reaction is very small compared to the pre-existing distribution of external energy when there is already a lot of energy in the surroundings.
- https://chem.libretexts.org/Courses/University_of_California_Davis/Chem_4B%3A_General_Chemistry_for_Majors_II_(Larsen)/Worksheets/02%3A_Thermochemistry_II_(Worksheet)As we saw last week, enthalpy and internal energy are state functions, which means that the sum of the heats of any set of steps that adds to give an overall reaction will have the same heat as doing ...As we saw last week, enthalpy and internal energy are state functions, which means that the sum of the heats of any set of steps that adds to give an overall reaction will have the same heat as doing the reaction directly -(Hess’s Law0. We will go on to see that if we use a special kind of thermochemical reaction, called the standard enthalpy of formation, we can calculate enthalpies of reactions without having to manipulate a series of individual thermochemical equations for each step.
- https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Inorganic_Chemistry_(LibreTexts)/06%3A_Acid-Base_and_Donor-Acceptor_Chemistry/6.03%3A_Brnsted-Lowry_Concept/6.3.05%3A_Thermodynamics_of_Solution-Phase_Brnsted_Acidity_and_BasicityThe text discusses the influence of solvation on the behavior of Br??nsted-Lowry acids and bases in aqueous systems, with a focus on thermochemical parameters such as enthalpy and entropy changes for ...The text discusses the influence of solvation on the behavior of Br??nsted-Lowry acids and bases in aqueous systems, with a focus on thermochemical parameters such as enthalpy and entropy changes for acid dissociation. The major driving force for dissociation is the enthalpy, which is exothermic for most acids, except for certain weak acids where entropy plays a larger role.
- https://chem.libretexts.org/Courses/Prince_Georges_Community_College/CHEM_2000%3A_Chemistry_for_Engineers_(Sinex)/Unit_6%3A_Thermo_and_Electrochemistry/Chapter_15%3A_First_Law_Thermochem/Chapter_15.4%3A_Hess's_LawAs shown in Figure 15.4.1, the first reaction produces 1 mol of solid aluminum oxide (Al 2 O 3 ) and 2 mol of liquid iron at its melting point of 1758°C (part (a) in Equation 15.4.1); the enthalpy cha...As shown in Figure 15.4.1, the first reaction produces 1 mol of solid aluminum oxide (Al 2 O 3 ) and 2 mol of liquid iron at its melting point of 1758°C (part (a) in Equation 15.4.1); the enthalpy change for this reaction is −732.5 kJ/mol of Fe 2 O 3 . The second reaction is the conversion of 2 mol of liquid iron at 1758°C to 2 mol of solid iron at 1758°C (part (b) in Equation 15.4.1); the enthalpy change for this reaction is −13.8 kJ/mol of Fe (−27.6 kJ per 2 mol Fe).
