Domanda del libro di testo
Using values from Appendix C, calculate the value of H for each of the following reactions: (a) NiO(s) + 2 HCl(g) → NiCl2(s) + H2O(g)
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Ch.5 - Thermochemistry
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970
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TOC.tableOfContents
- Ch.1 - Introduction: Matter, Energy, and Measurement146
- Ch.2 - Atoms, Molecules, and Ions200
- Ch.3 - Chemical Reactions and Reaction Stoichiometry176
- Ch.4 - Reactions in Aqueous Solution155
- Ch.5 - Thermochemistry126
- Ch.6 - Electronic Structure of Atoms131
- Ch.7 - Periodic Properties of the Elements126
- Ch.8 - Basic Concepts of Chemical Bonding123
- Ch.9 - Molecular Geometry and Bonding Theories143
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces91
- Ch.12 - Solids and Modern Materials122
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics174
- Ch.15 - Chemical Equilibrium101
- Ch.16 - Acid-Base Equilibria139
- Ch.17 - Additional Aspects of Aqueous Equilibria146
- Ch.18 - Chemistry of the Environment72
- Ch.19 - Chemical Thermodynamics129
- Ch.20 - Electrochemistry142
- Ch.21 - Nuclear Chemistry101
- Ch.22 - Chemistry of the Nonmetals68
- Ch.23 - Transition Metals and Coordination Chemistry66
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry10
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Non è quello che usi tu?Cambia libro di testo
Capitolo 5, Problema 78
Calcium carbide (CaC2) reacts with water to form acetylene (C2H2) and Ca(OH)2. From the following enthalpy of reaction data and data in Appendix C, calculate H°f for CaC2(s): CaC2(s) + 2 H2O(l) → Ca(OH2)(s) + C2H2(g) ΔH° = -127.2 kJ
Guida verificata passo dopo passo1
Identify the given chemical reaction: \( \text{CaC}_2(s) + 2 \text{H}_2\text{O}(l) \rightarrow \text{Ca(OH)}_2(s) + \text{C}_2\text{H}_2(g) \) with \( \Delta H^\circ = -127.2 \text{ kJ} \).
Use the formula for the standard enthalpy change of reaction: \( \Delta H^\circ = \sum \Delta H^\circ_f(\text{products}) - \sum \Delta H^\circ_f(\text{reactants}) \).
Look up the standard enthalpy of formation values for \( \text{Ca(OH)}_2(s) \) and \( \text{C}_2\text{H}_2(g) \) in Appendix C.
Set up the equation: \( -127.2 \text{ kJ} = [\Delta H^\circ_f(\text{Ca(OH)}_2) + \Delta H^\circ_f(\text{C}_2\text{H}_2)] - [\Delta H^\circ_f(\text{CaC}_2) + 2 \times \Delta H^\circ_f(\text{H}_2\text{O})] \).
Solve for \( \Delta H^\circ_f(\text{CaC}_2) \) using the known values from Appendix C and the given \( \Delta H^\circ \).
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Enthalpy of Reaction
Enthalpy of reaction, denoted as ΔH, is the heat change associated with a chemical reaction at constant pressure. It indicates whether a reaction is exothermic (releases heat, ΔH < 0) or endothermic (absorbs heat, ΔH > 0). In the given reaction, the negative ΔH value of -127.2 kJ signifies that the reaction releases energy, which is crucial for calculating the standard enthalpy of formation.
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02:34
Enthalpy of Formation
Standard Enthalpy of Formation (H°f)
The standard enthalpy of formation (H°f) is the change in enthalpy when one mole of a compound is formed from its elements in their standard states. It is a key concept in thermodynamics and is used to calculate the enthalpy changes in reactions. To find H°f for CaC2(s), one must apply Hess's law, which states that the total enthalpy change for a reaction is the sum of the enthalpy changes for individual steps.
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02:34Enthalpy of Formation
Hess's Law
Hess's Law states that the total enthalpy change for a chemical reaction is the same, regardless of the number of steps or the pathway taken. This principle allows chemists to calculate the enthalpy change of a reaction indirectly by using known enthalpy changes of other reactions. In this case, it can be applied to derive the standard enthalpy of formation for CaC2(s) by combining the enthalpy of the given reaction with the enthalpies of formation of the products and reactants.
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02:03Hess's Law
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