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156 solutions

Hess's Law

Q. Part C. The average bond enthalpy for C − H is 413 kJ / mol. 413 kJ of energy is required to break a mole of CH into atoms:CH(g) → C(g) + H(g), ΔH ...

Solved • Jul 2, 2020

Hess's Law

Q. Click on the ΔH changes sign when a process is reversed button within the activity and analyze the relationship between the two reactions that are ...

Solved • Jul 2, 2020

Hess's Law

Q. Click the ΔH is an extensive property button within the activity, and analyze the relationship between the two reactions that are displayed. The re...

Solved • Jul 2, 2020

Hess's Law

Q. The ionization energy for sodium is 496 kJ/mol. The electron affinity for chlorine is -349 kJ/mol. Use these values and Hess's law to calculate the...

Solved • Jul 2, 2020

Hess's Law

Q. Part B. Calculate the enthalpy of the reaction4B(s) + 3O2(g) → 2B2O3(s)Given the following pertinent information:1. B2O3(s) + 3H2O(g) → 3O2(g) + B2...

Solved • Jul 2, 2020

Hess's Law

Q. Part A. Calculate the enthalpy of the reaction2NO(g) + O2(g) → 2NO2(g)Given the following reactions and enthalpies of formation:1. 1/2 N2(g) + O2(g...

Solved • Jul 2, 2020

Hess's Law

Q. What is the enthalpy for the following reaction?overall: C2H4 + H2O → C2H5OHExpress your answer numerically in kilojoules per mole.The change in en...

Solved • Jul 2, 2020

Hess's Law

Q. What is the enthalpy for reaction 1 reversed?reaction 1 reversed: 2 CO2 + 3 H2O → C2H5OH + 3 O2Express your answer numerically in kilojoules per mo...

Solved • Jul 2, 2020

Hess's Law

Q. The equations given in the problem introduction can be added together to give the following reaction:overall: C2H4 + H2O → C2H5OHHowever, one of th...

Solved • Jul 2, 2020

Hess's Law

Q. Why are tables of standard enthalpies of formation so useful?

Solved • Jun 30, 2020

Hess's Law

Q. We can calculate ΔH for the reaction: C(s) + H2O(g) → CO(g) + H2 (g) using the following thermochemical equations: C(s) + O2 (g) → CO2 (g)         ...

Solved • Jun 30, 2020

Hess's Law

Q. Consider the two diagrams below.How do these diagrams relate to Hess s law?

Solved • Jun 30, 2020

Hess's Law

Q. What is the connection between Hess's law and the fact that H is a state function?

Solved • Jun 30, 2020

Hess's Law

Q. Consider the following chemical equation:2A + B → C        ΔHrxn = 128 JWhat is ΔHrxn for the reaction:2C → 4A + 2BExpress your answer in joules to...

Solved • Jun 25, 2020

Hess's Law

Q. The 1995 Nobel Prize in Chemistry was shared by Paul Crutzen, F. Sherwood Rowland, and Mario Molina for their work concerning the formation and dec...

Solved • Jun 17, 2020

Hess's Law

Q. Consider this combination reaction: 2Mg(s) + O2(g) → 2MgO(s)        ΔH = -1204 kJWhat is the enthalpy for the decomposition of 1 mole of MgO(s) int...

Solved • May 1, 2020

Hess's Law

Q. The enthalpy change, ΔH, for a few reactions are given. → H2O(l)                     ΔH = -286 kJ/molCa(s) + 2H+(aq) → Ca2+(aq) + H2(g)           Δ...

Solved • Apr 29, 2020

Hess's Law

Q. Calculate ΔHrxn for the following reaction: CH4(g)+4Cl2(g)→CCl4(g)+4HCl(g) Use the following reactions and given ΔH′s. C(s)+2H2(g)→CH4(g)     ΔH=−7...

Solved • Apr 14, 2020

Hess's Law

Q. Match each chemical reaction with the correct diagram according to Hess' LawΔHC = -ΔHA + ΔHB ΔHB  = ΔHA  + ΔHCΔHA = ΔHB - ΔHCΔHB  = -ΔHA - ΔHC ΔHA ...

Solved • Mar 20, 2020

Hess's Law

Q. Consider these reactions, where M represents a generic metal. 1. 2 M(s) + 6 HCl(aq) → 2 MCl3(aq) + 3 H2(g)             ΔH1 = -623.0 kJ2. HCl(g) → H...

Solved • Mar 20, 2020

Hess's Law

Q. Calculate the enthalpy of the reaction2NO(g) + O2(g) → 2NO2(g)Given the following reactions and enthalpies of formation:½ N2(g) + O2(g) → NO2(g) Ch...

Solved • Mar 17, 2020

Hess's Law

Q. Given the following thermochemical data:Fe2O3(s) + CO(g) → 2 FeO(s) + CO2(g)         ∆H = −2.9 kJFe(s) + CO2(g) → FeO(s) + CO(g)                  ∆...

Solved • Nov 29, 2019

Hess's Law

Q. From the enthalpies of reaction2C(s) + O2 (g) → 2CO(g)                          ΔH   rxn = -221.0 kJ2C(s) + O2 (g) + 4H2 (g) → 2CH3OH(g)    ΔHrxn =...

Solved • Oct 18, 2019

Hess's Law

Q. Given:1. A → 2B, ΔH1 2. B → C + D, ΔH2 3. E → 2D, ΔH3ΔH of A → 2C + E is:A. ΔH1 + 2ΔH2 – ΔH3 B. ΔH2 - ΔH2 – ΔH3 C. ΔH3 – ΔH3 D. ΔH1 + 2ΔH1 – ΔH2 E....

Solved • Oct 9, 2019

Hess's Law

Q. Given the following thermochemical data:                                                                                ∆H°f (kJ)I. P4(s) + 6 Cl2(g...

Solved • Oct 3, 2019

Hess's Law

Q. Given the following reactionsH2O (l) →H2O (g)                    ΔH = 44.01 kJ2H2 (g) + O2 (g) → 2H2O (g)  ΔH = -483.64 kJthe enthalpy for the deco...

Solved • Oct 1, 2019

Hess's Law

Q. From the enthalpies of reaction2 C(s) + O2(g) → 2CO(g)                               ΔH = -221.0 kJ2C(s) + O2(g) + 4H2(g) → 2CH3OH(g)       ΔH = -4...

Solved • Sep 15, 2019

Hess's Law

Q. Calculate the ΔH (in kJ) for the reaction:3 Fe2O3 (s) + CO (g) → CO2 (g) + 2 Fe3O4 (s)             ∆Hrxn = ?Given the following reactions:Fe2O3 (s)...

Solved • Sep 13, 2019

Hess's Law

Q. (i) Consider this reactionC2H5OH + 3O2 → 2CO2 + 3H2O Change in Heat = -1370 kJ/molWhat is the enthalpy for this reaction reversed?Reaction reversed...

Solved • Jul 10, 2019

Hess's Law

Q. Find ΔHrxn for the following reaction: 3 H2(g) + O3(g) → 3H2O(g)Use the following reactions with known ΔH values:2 H2(g) + O2(g) → 2 H2O(g); ΔH = –...

Solved • Nov 12, 2018

Hess's Law

Q. Find ΔHrxn for the following reaction: N2O(g) + NO2(g) → 3 NO(g)Use the following reactions with known ΔH values:2 NO(g) + O2(g) → 2 NO2(g); ΔH = –...

Solved • Nov 12, 2018

Hess's Law

Q. Calculate ΔHrxn for the following reaction: CaO(s) + CO2(g) → CaCO3(s)Use the following reactions and given ΔH’s:Ca(s) + CO2(g) + 1/2 O2(g) → CaCO3...

Solved • Nov 12, 2018

Hess's Law

Q. Calculate ΔHrxn Delta  H_{ m rxn} for the following reaction: CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g)Given these reactions and their ΔH values:C(s) + ...

Solved • Nov 12, 2018

Hess's Law

Q. Consider the following generic reaction: A + 2B → C + 3D, with ΔH = 148 kJ . Determine the value of ΔH for the following related reaction: 3A + 6B ...

Solved • Nov 12, 2018

Hess's Law

Q. Consider the following generic reaction: A + 2B → C + 3D, with ΔH = 148 kJ. Determine the value of ΔH for the following related reaction: C + 3D → ...

Solved • Nov 12, 2018

Hess's Law

Q. Consider the reactions:A → 2 B; ΔH1A → 3 C; ΔH2What is ΔH for the reaction 2 B → 3 C?

Solved • Nov 12, 2018

Hess's Law

Q. The ΔHf˚ of TiI3(s) is –328 kJ/mol and the ΔH˚ for the reaction Ti(s) + 3 I 2(g) → 2 TiI3(s) for the reaction is –839 kJ{ m kJ}. Calculate the ΔH o...

Solved • Nov 12, 2018

Hess's Law

Q. For each generic reaction, determine the value of ΔH2 in terms of ΔH1.A + B → 2C; ΔH12C → A + B; ΔH2 = ?

Solved • Nov 12, 2018

Hess's Law

Q. For each generic reaction, determine the value of ΔH2 in terms of ΔH1.A + 1/2B → C; ΔH12A + B → 2C; ΔH2 = ?

Solved • Nov 12, 2018

Hess's Law

Q. For each generic reaction, determine the value of ΔH2 in terms of ΔH1.A → B + 2C; ΔH11/2B + C → 1/2A; ΔH2 = ?

Solved • Nov 12, 2018

Hess's Law

Q. Calculate ΔHrxn for the following reaction: Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g)Use the following reactions and given ΔH's.2 Fe(s) + 3/2 O2(g) →...

Solved • Nov 12, 2018

Hess's Law

Q. Calculate ΔHrxn for the following reaction: 5 C(s) + 6 H2(g) → C5H12(l)Use the following reactions and given ΔH's.C5H12(l) + 8 O2(g) → 5 CO2(g) + 6...

Solved • Nov 12, 2018

Hess's Law

Q. Explain how the value of ΔH for a reaction changes upon multiplying the reaction by a factor.

Solved • Nov 12, 2018

Hess's Law

Q. Explain how the value of ΔH for a reaction changes upon reversing the reaction.

Solved • Nov 12, 2018

Hess's Law

Q. Explain how the value of ΔH for a reaction changes upon.• multiplying the reaction by a factor• reversing the reactionWhy do these relationships hold?

Solved • Nov 12, 2018

Hess's Law

Q. What is Hess' law?

Solved • Nov 12, 2018

Hess's Law

Q. What is Hess's law? Why is it useful?

Solved • Nov 12, 2018

Hess's Law

Q. You may want to reference (Pages 183 - 186)Section 5.6 while completing this problem.Calculate ΔH for 2 NO(g) + O2(g) → N2O4(g) using the following...

Solved • Oct 31, 2018

Hess's Law

Q. We can use Hess' law to calculate enthalpy changes that cannot be measured. One such reaction is the conversion of methane to ethylene: 2 CH4(g) → ...

Solved • Oct 31, 2018

Hess's Law

Q. Consider the combustion of liquid methanol, CH3OH(l): CH3OH(l) + 3/2 O2 (g) → CO2(g) + 2 H2O(l), ΔH = –726.5kJBalance the forward reaction with who...

Solved • Oct 31, 2018

Hess's Law

Q. Enthalpy diagram illustrating Hesss law. The net reaction is the same as in Figure 5.21 in the textbook, but here we imagine different reactions in...

Solved • Oct 31, 2018

Hess's Law

Q. Calculate the enthalpy change for the reaction: P4O6(s) + 2 O2(g) → P4O10(s), given the following enthalpies of reaction:P4(s) + 3 O2(g) → P4O6(s),...

Solved • Oct 31, 2018

Hess's Law

Q. From the enthalpies of reaction:H2(g) + F2(g) → 2 HF(g), ΔH = –537 kJC(s) + 2F2(g) → CF4(g), ΔH = –680 kJ2 C(s) + 2 H2(g) → C2H4(g), ΔH = +52.3 kJc...

Solved • Oct 31, 2018

Hess's Law

Q. You may want to reference(Pages 183 - 186)Section 5.6 while completing this problem.Given the following data:N2(g) +  O2(g) →  2NO(g)           ΔH ...

Solved • Oct 31, 2018

Hess's Law

Q. You may want to reference (Pages 184 - 186) Section 5.6 while completing this problem.From the enthalpies of reaction2 C(s) + O2(g) → 2 CO(g), ΔH =...

Solved • Oct 31, 2018

Hess's Law

Q. Even though so much energy is required to form a metal cation with a 2+ charge, the alkaline earth metals form halides with the general formula MX2...

Solved • Oct 23, 2018

Hess's Law

Q. Calculate ΔH for the reaction N2H4 (l) + O2 (g) → N2 (g) + 2H2O (l)given the following data2 NH3 (g) + 3N2O (g) → 4N2(g) + 3H2O (l)      ΔH = -1010...

Solved • Oct 19, 2018

Hess's Law

Q. Using the following data, calculate the standard heat of formation of ICl(g) in kJ/mol:Cl2 (g) → 2Cl (g)          ΔH° = 242.3 kJI2 (g) → 2I (g)    ...

Solved • Oct 19, 2018

Hess's Law

Q. Given the following dataFe2O3 (s) + 3 CO (g) → 2 Fe (s) + 3 CO2 (g)         ΔH° = -23 kJ3Fe2O3 (s) + CO (g) → 2 Fe3O4 (s) + CO2 (g)     ΔH° = -39 k...

Solved • Oct 18, 2018

Hess's Law

Q. Given the following dataCa(s) + 2C (graphite) → CaC2 (s)                      ΔH = -62.8 kJCa(s) + 1/2 O2 (g) → CaO (s)                            ...

Solved • Oct 18, 2018

Hess's Law

Q. Calculate ΔH for the reaction2NH3 (g) + 1/2 O2 (g) → N2H4 (l) + H2O (l) given the following data:2NH3 (g) + 3N2O (g) → 4N2 (g) + 3H2O (l)  ΔH = -10...

Solved • Oct 18, 2018

Hess's Law

Q. Given the following data2 O3 (g) → 3 O2 (g)            ΔH = -427 kJO2 (g) → 2O (g)                  ΔH = 495 kJNO (g) + O3 (g) → NO2 (g) + O2 (g)  ...

Solved • Oct 18, 2018

Hess's Law

Q. Given the following data:2ClF (g) + O2 (g) → Cl2O (g)+ F2O (g)              ΔH = 167.4 kJ2ClF3 (g) + 2O2 (g) → Cl2O (g) + 3F2O (g)       ΔH = 341.4...

Solved • Oct 18, 2018

Hess's Law

Q. Given the following data:Calculate ΔH for the reaction On the basis of the enthalpy change, is this a useful reaction for the synthesis of ammonia?  

Solved • Oct 18, 2018

Hess's Law

Q. Calculate ΔH°298 for the process Zn(s) + S(s) + 2O 2(g) ⟶ ZnSO4(s)from the following information:Zn(s) + S(s) ⟶ ZnS(s)                  ΔH° 298 = −...

Solved • Oct 16, 2018

Hess's Law

Q. Calculate ΔH°298 for the process Sb(s) + 5/2Cl2(g) ⟶ SbCl5(s)from the following information:Sb(s) + 3/2Cl2(g) ⟶ SbCl3(s)             ΔH°298 = −314 ...

Solved • Oct 16, 2018

Hess's Law

Q. Calculate the standard molar enthalpy of formation of NO(g) from the following data:N2(g) + 2O2 ⟶ 2NO2(g) ΔH°298 = 66.4 kJ2NO(g) + O2 ⟶ 2NO2(g) ΔH°...

Solved • Oct 16, 2018

Hess's Law

Q. Calculate ΔH°298 for the process Co3O4(s) ⟶ 3Co(s) + 2O2(g) from the following information: Co(s) + 1/2O2(g) ⟶ CoO(s)  ΔH°298 = −237.9kJ 3CoO(s) +1...

Solved • Oct 16, 2018

Hess's Law

Q. The following sequence of reactions occurs in the commercial production of aqueous nitric acid:4NH3(g) + 5O2(g) ⟶ 4NO(g) + 6H2O(l)           ΔH = −...

Solved • Oct 16, 2018

Hess's Law

Q. Calculate ΔH for the process Hg 2Cl2(s) ⟶ 2Hg(l) + Cl2(g) from the following information:Hg(l) + Cl2(g) ⟶ HgCl2(s) ΔH = −224 kJHg(l) + HgCl2(s) ⟶ H...

Solved • Oct 16, 2018

Hess's Law

Q. Reaction of gaseous ClF with F 2 yields liquid ClF3, an important fluorinating agent. Use the following thermochemical equations to calculate ΔH°rx...

Solved • Oct 16, 2018

Hess's Law

Q. Diamond and graphite are two crystalline forms of carbon. At 1 atm and 25°C, diamond changes to graphite so slowly that the enthalpy change of the ...

Solved • Oct 15, 2018

Hess's Law

Q. Write the balanced overall equation (equation 3) for the following process, calculate ΔHoverall, and match the number of each equation with the let...

Solved • Oct 15, 2018

Hess's Law

Q. Calculate ΔH for2NOCl (g) ⟶ N2 (g) + O2 (g) + Cl2 (g)given the following reactions:1/2N2 (g) + 1/2O2 (g) ⟶ NO (g)         Δ H = 90.3 kJNO (g) + 1/2...

Solved • Oct 15, 2018

Hess's Law

Q. Calculate ΔH forCa (s) + 1/2O2 (g) + CO2 (g) ⟶ CaCO3 (s)given the following reactions:Ca (s) + 1/2O2 (g) ⟶ CaO (s)             Δ H = −635.1 kJCaCO3...

Solved • Oct 15, 2018

Hess's Law

Q. Consider the following balanced thermochemical equation for the decomposition of the mineral magnesite:MgCO3 (s) ⟶ MgO (s) + CO2 (g)               ...

Solved • Oct 15, 2018

Hess's Law

Q. A chemist measures the enthalpy change ΔH during the following reaction: CS2 (g) + 3Cl2 (g) → CCl4 (l) + S2Cl2 (l)     ΔH = -304. kJ Use this infor...

Solved • Sep 14, 2018

Hess's Law

Q. A chemist measures the enthalpy change ΔH during the following reaction: P4 (s) + 6Cl2 (g) → 4 PCl3 (g)       ΔH = -1148.kJ Use this information to...

Solved • Sep 14, 2018

Hess's Law

Q. A chemist measures the enthalpy change ΔH during the following reaction: 2H2O (l) + O2 (g) → 2H2O2 (l)            ΔH = 196. kJ Use this information...

Solved • Sep 14, 2018

Hess's Law

Q. Given the following data (1) 2ClF (g) + O2 (g) → Cl2O (g) + OF2 (g)         ΔH°rxn = 167.5 kJ (2) 2F2 (g) + O2 (g) → 2OF2 (g)                      ...

Solved • Aug 21, 2018

Hess's Law

Q. Use the following data to calculate the standard heat (enthalpy) of formation, ΔH °f, of manganese(IV) oxide, MnO2 (s). 2MnO2 (s) → 2MnO (s) + O2 (...

Solved • Aug 21, 2018

Hess's Law

Q. Enter your answer in the provided box.From these data, S (rhombic) + O2 (g) → SO2 (g)            ΔH°rxn = -296.06 kJ/mol S (monoclinic) + O2 (g) → ...

Solved • Aug 9, 2018

Hess's Law

Q. Given that H2 (g) + F2 (g) → 2HF (g)     ΔH°rxn = - 546.6 kJ 2H2 (g) + O2 (g) → 2H2O (l)     ΔH°rxn = - 571.6 kJ calculate the value of ΔH°rxn for ...

Solved • Aug 8, 2018

Hess's Law

Q. Given these reactions, X (s) + 1/2O2 (g) → XO (s)     ΔH = -993.7 kJ XCO3 (s) → XO (s) + CO2 (g)     ΔH = +424.5 kJ What is ΔHrxn for this reaction...

Solved • Aug 8, 2018

Hess's Law

Q. Calculate ΔH°rxn for the reaction 2Ni (s) + 2S (s) + 3O2 (g) → 2NiSO3 (s) from the following information: (1) NiSO3 (s) → NiO (s) + SO3 (g)     ΔH°...

Solved • Aug 8, 2018

Hess's Law

Q. Research is being carried out on cellulose as a source of chemicals for the production of fibers, coatings and plastics. Cellulose consists of long...

Solved • Aug 8, 2018

Hess's Law

Q. Use the following data to determine the Delta H for the conversion of diamond into graphite: Cdiamond (s) + O2 (g) → CO2 (g)    ΔH° = -395.4 kJ 2CO...

Solved • Aug 8, 2018

Hess's Law

Q. Using data from the following reactions and applying Hess's law, calculate the heat change for the slow reaction of zinc with water: Zn (s) + 2H2O ...

Solved • Aug 8, 2018

Hess's Law

Q. The enthalpy of decomposition of NO2Cl is -114 kJ. Use the following data to calculate the heat of formation of NO2Cl from N2, O2, and Cl2: NO2Cl (...

Solved • Aug 7, 2018

Hess's Law

Q. Calculate the enthalpy of formation of SO2 (g) from the standard enthalpy changes of the following reactions: 2SO2 (g) + O2 (g) → 2SO3(g)          ...

Solved • Aug 7, 2018

Hess's Law

Q. How can the first two reactions be combined to obtain the third reaction? Include phases in the balanced chemical equation. 

Solved • Aug 1, 2018

Hess's Law

Q. Enter your answer in the provided box.You are given the following data: H2 (g) → 2H (g) ΔH° = -436.4 kJ/mol Br2 (g) → 2Br (g) ΔH° = 192.5 kJ/mol H2...

Solved • Aug 1, 2018

Hess's Law

Q. Given the standard enthalpy changes for the following two reactions: 4C (s) + 5H2 (g) → C4H10 (g)      ΔH° = -125.6 kJ C2H4 (g) → 2C (s) + 2H2 (g) ...

Solved • Jul 25, 2018

Hess's Law

Q. Find ΔH° for BaCO3 (s) → BaO (s) + CO2 (g) given that 2Ba (s) + O2 (g) → 2BaO (s)     ΔH° = -1107.0 kJBa (s) + CO2 (g) + 1/2O2 (g)→ BaCO3 (s)     Δ...

Solved • Jul 17, 2018

Hess's Law

Q. Calculate the enthalpy of the reaction 4B (s) + 3O2 (g) → 2B2O3 (s) given the following pertinent information: 1. B2O3 (s) + 3H2O (g)  → 3O2 (g) + ...

Solved • Jul 10, 2018

Hess's Law

Q. Calculate the enthalpy of the reaction 2NO (g) + O2 (g) → 2NO2 (g) given the following reactions and enthalpies of formation: 1. 1/2N2 (g) + O2 (g)...

Solved • Jul 10, 2018

Hess's Law

Q. Consider the equations below. (1) Ca (s) + CO2 (g) + 1/2O2 (g) → CaCO3 (s) (2) 2Ca (s) + O2 (g) → 2CaO (s) How should you manipulate these equation...

Solved • Jul 9, 2018

Hess's Law

Q. Calculate the ΔH° for the following reaction using the information below it. C2H5OH (l) + O2 (g) → CH3CO2H (l) + H2O (l): ΔH° = ? C2H5OH (l) + 1/2O...

Solved • Jul 4, 2018

Hess's Law

Q. The combustion reaction of butane is as follows. C4H10(g) + 13/2 O2(g) → 4 CO2(g) + 5 H2O(l) Using Hess's law and the reaction enthalpies given bel...

Solved • Jun 19, 2018

Hess's Law

Q. Consider the following chemical reaction. NH3(g) + 2 O2(g) → HNO3(aq) + H2O(l) Calculate the change in enthalpy (ΔH) for this reaction, using Hess'...

Solved • Jun 19, 2018