Concept explainers
Interpretation:
“Enthalpy” and “enthalpy of reaction” are to be defined and also the conditions under which heat of reaction equal to the enthalpy change of reaction is to be explained.
Concept introduction:
Enthalpy of a system is the
Equation for enthalpy is
where
For any reaction, the change in enthalpy, called as the enthalpy of reaction
The enthalpy of reaction can be positive or negative, depending on the process. For an endothermic process,
Want to see the full answer?
Check out a sample textbook solutionChapter 5 Solutions
ALEKS 360-ACCESS (1 SEMESTER)
- Compounds with carboncarbon double bonds, such as ethylene, C2H4, add hydrogen in a reaction called hydrogenation. C2H4(g)+H2(g)C2H6(g) Calculate the enthalpy change for this reaction, using the following combustion data: C2H4(g)+3O2(g)2CO2(g)+2H2O(l);H=1411kJC2H6(g)+72O2(g)2CO2(g)+3H2O(l);H=1560kJH2(g)+12O2(g)H2O(l);H=286kJarrow_forwardWhich of the enthalpies of combustion in Table 5.2 the table are also standard enthalpies of formation?arrow_forwardYou discover that you cannot carry out a particular reaction for which you would like the enthalpy change. Does this mean that you will be unable to obtain this enthalpy change? Explain.arrow_forward
- When 2.50 g of methane burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion per mole of methane under these conditions?arrow_forwardThe enthalpy change for the following reaction is 393.5 kJ. C(s,graphite)+O2(g)CO2(g) (a) Is energy released from or absorbed by the system in this reaction? (b) What quantities of reactants and products are assumed? (c) Predict the enthalpy change observed when 3.00 g carbon burns in an excess of oxygen.arrow_forwardUnder what circumstances is the heat of a process equal to the enthalpy change for the process?arrow_forward
- The first step in the preparation of lead from its ore (galena, PbS) consists of roasting the ore. PbS(s)+32O2(g)SO2(g)+PbO(s) Calculate the standard enthalpy change for this reaction, using enthalpies of formation (see Appendix C).arrow_forwardHydrazine, N2H4, is a colorless liquid used as a rocket fuel. What is the enthalpy change for the process in which hydrazine is formed from its elements? N2(g)+2H2(g)N2H4(l) Use the following reactions and enthalpy changes: N2H4(l)+O2(g)N2(g)+2H2O(l);H=622.2kJH2(g)+12O2(g)H2O(l);H=285.8kJarrow_forwardFor the reactions of molecular hydrogen with fluorine and with chlorine: (a) Calculate the enthalpy change for breaking all the bonds in the reactants. (b) Calculate the enthalpy change for forming all the bonds in the products. (c) From the results in parts (a) and (b), calculate the enthalpy change for the reaction. (d) Which reaction is most exothermic?arrow_forward
- A 0.470-g sample of magnesium reacts with 200 g dilute HCl in a coffee-cup calorimeter to form MgCl2(aq) and H2(g). The temperature increases by 10.9 C as the magnesium reacts. Assume that the mixture has the same specific heat as water and a mass of 200 g. (a) Calculate the enthalpy change for the reaction. Is the process exothermic or endothermic? (b) Write the chemical equation and evaluate H.arrow_forwardThe equation for the fermentation of glucose to alcohol and carbon dioxide is: C6H12O6(aq) 2C2H5OH(aq) + 2CO2(g) The enthalpy change for the reaction is 67 kJ. Is this reaction exothermic or endothermic? Is energy, in the form of heat, absorbed or evolved as the reaction occurs?arrow_forwardWhat mass of acetylene, C2H2(g), must be burned to produce 3420 kJ of heat, given that its enthalpy of combustion is 1301 kJ/mol? Compare this with the answer to Exercise 5.91 and determine which substance produces more heat per gram.arrow_forward
- World of Chemistry, 3rd editionChemistryISBN:9781133109655Author:Steven S. Zumdahl, Susan L. Zumdahl, Donald J. DeCostePublisher:Brooks / Cole / Cengage LearningGeneral Chemistry - Standalone book (MindTap Cour...ChemistryISBN:9781305580343Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; DarrellPublisher:Cengage LearningChemistry: Principles and PracticeChemistryISBN:9780534420123Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward MercerPublisher:Cengage Learning
- World of ChemistryChemistryISBN:9780618562763Author:Steven S. ZumdahlPublisher:Houghton Mifflin College DivIntroductory Chemistry: A FoundationChemistryISBN:9781337399425Author:Steven S. Zumdahl, Donald J. DeCostePublisher:Cengage LearningChemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage Learning