Concept explainers
a)
Interpretation:
The standard enthalpy of formation of
Concept Introduction:
The change in enthalpy that is associated with the formation of one mole of a substance from its related elements being in standard state is called standard enthalpy of formation (
The standard enthalpy of reaction is the enthalpy of reaction that takes place under standard conditions.
The equation for determining the standard enthalpies of compound and element can be given by,
b)
Interpretation:
The standard enthalpy of formation of
Concept Introduction:
The change in enthalpy that is associated with the formation of one mole of a substance from its related elements being in standard state is called standard enthalpy of formation (
The standard enthalpy of reaction is the enthalpy of reaction that takes place under standard conditions.
The equation for determining the standard enthalpies of compound and element can be given by,
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CHEMISTRY:ATOMS FIRST-2 YEAR CONNECT
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- The formation of aluminum oxide from its elements is highly exothermic. If 2.70 g Al metal is burned in pure O2 to give A12O3, calculate how much thermal energy is evolved in the process (at constant pressure).arrow_forwardCoal is used as a fuel in some electric-generating plants. Coal is a complex material, but for simplicity we may consider it to be a form of carbon. The energy that can be derived from a fuel is sometimes compared with the enthalpy of the combustion reaction: C(s)+O2(g)CO2(g) Calculate the standard enthalpy change for this reaction at 25C. Actually, only a fraction of the heat from this reaction is available to produce electric energy. In electric generating plants, this reaction is used to generate heat for a steam engine, which turns the generator. Basically the steam engine is a type of heat engine in which steam enters the engine at high temperature (Th), work is done, and the steam then exits at a lower temperature (Tl). The maximum fraction, f, of heat available to produce useful energy depends on the difference between these temperatures (expressed in kelvins), f = (Th Tl)/Th. What is the maximum heat energy available for useful work from the combustion of 1.00 mol of C(s) to CO2(g)? (Assume the value of H calculated at 25C for the heat obtained in the generator.) It is possible to consider more efficient ways to obtain useful energy from a fuel. For example, methane can be burned in a fuel cell to generate electricity directly. The maximum useful energy obtained in these cases is the maximum work, which equals the free-energy change. Calculate the standard free-energy change for the combustion of 1.00 mol of C(s) to CO2(g). Compare this value with the maximum obtained with the heat engine described here.arrow_forward9.42 Why is enthalpy generally more useful than internal energy in the thermodynamics of real world systems?arrow_forward
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- A pot of cold water is heated on a stove, and when the water boils, a fresh egg is placed in the water to cook. Describe the events that are occurring in terms of the zeroth law of thermodynamics.arrow_forwardThe decomposition of ozone, O3, to oxygen, O2, is an exothermic reaction. What is the sign of q? If you were to touch a flask in which ozone is decomposing to oxygen, would you expect the flask to feel warm or cool?arrow_forwardFor the reaction TiCl2(s) + Cl2(g) TiCl4(), rG = 272.8 kj/mol-txn. Using this value and other data available in Appendix L, calculate the value of fG for TiCl2(s).arrow_forward
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