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178 solutions

Hess's Law

Q. Hess's law is based on:A. Law of conservation of massB. Law of conservation of energyC. Second law of thermodynamicsD. None of the above

Solved • Apr 14, 2021

Hess's Law

Q. How do you use Hess's Law to calculate the enthalpy change for the reaction?WO3(s) + 3 H2(g) → W(S) + 3 H2O(g) from the following equations: 2 W(s)...

Solved • Apr 6, 2021

Hess's Law

Q. You have a series of four chemical reactions (1 --> 2 --> 3 --> 4). How do you calculate the Δ H2 if you know the other ΔH values?

Solved • Apr 6, 2021

Hess's Law

Q. There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. In the first step, cal...

Solved • Apr 2, 2021

Hess's Law

Q. Now consider the following set of reactions:2 NO2 → 2 NO + O2, ΔH = 109 kJ/molN2O4 → 2 NO + O2, ΔH = 172 kJ/molPart AThe equations given in the pro...

Solved • Apr 2, 2021

Hess's Law

Q. Calculate ΔHrxn for the following reaction: CH4(g)+2O2(g)→CO2(g)+2H2O(l) Use the following reactions and given ΔH′s. CH4(g)+O2(g)→CH2O(g)+H2O(g), Δ...

Solved • Mar 30, 2021

Hess's Law

Q. Given these reactions,X(s) +1/2 O2(g) → XO(s)ΔH=-539.5 kJXCO3(s) →  XO(s)+CO2(g)ΔH=+266.3 kJwhat is ΔHrxn for this reaction?X(s)+1/2 O2(g)+CO2(g) →...

Solved • Mar 30, 2021

Hess's Law

Q. What is the heat of reaction (ΔH°rxn) for the combustion of acetone (C3H6O) given the following thermochemical equations? (Answer should come out t...

Solved • Feb 24, 2021

Hess's Law

Q. Given the following thermochemical equations:A(g)  → B(g)                    ΔH = 90 kJB(g) → C(g)                     ΔH = -140 kJFind the enthalp...

Solved • Feb 9, 2021

Hess's Law

Q. Given the following thermochemical equations:A(g)  → B(g)                    ΔH = 90 kJB(g) → C(g)                     ΔH = -140 kJFind the enthalp...

Solved • Feb 9, 2021

Hess's Law

Q. Given the following thermochemical equations:A(g)  → B(g)                    ΔH = 90 kJB(g) → C(g)                     ΔH = -140 kJFind the enthalp...

Solved • Feb 4, 2021

Hess's Law

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

Solved • Nov 18, 2020

Hess's Law

Q. What is the enthalpy for reaction 1 reversed?reaction 1 reversed: CO2 (g) → CO (g) + 1/2 O2 (g)

Solved • Oct 23, 2020

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. 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. 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. Consider this reactionC2H5OH + 3 O2 → 2 CO2 + 3 H2O    ΔH = -1370 kJ/molWhat is the enthalpy for this reaction reversed?reaction reversed: 2CO2 + 3...

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. Can you use an approach similar to Hess's law to calculate the change in internal energy, E, for an overall reaction by summing the E values of ind...

Solved • Oct 31, 2018

Hess's Law

Q. Consider the two diagrams below.Based on (i), write an equation showing how HA is related to HB and HC.

Solved • Oct 31, 2018

Hess's Law

Q. Consider the two diagrams below.Based on (ii), write an equation relating HZ to the other enthalpy changes in the diagram.

Solved • Oct 31, 2018

Hess's Law

Q. Consider the two diagrams below.Equation from Part A: ΔHA = ΔHB + ΔHCEquation from Part B: ΔHZ = ΔHX + ΔHYThe equations you obtained in parts (a) a...

Solved • Oct 31, 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 = –726.5kJWhat is the enthalpy change for the r...

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. Consider the decomposition of liquid benzene, C6H6(l), to gaseous acetylene, C2H2(g): C6H6(l) → 3 C2H2(g), ΔH = +630 kJWhat is the enthalpy change ...

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. Hess's law provides a useful means of calculating energy changes that are difficult to measure directly. For instance, it is impossible to measure ...

Solved • Oct 31, 2018

Hess's Law

Q. Hess’s law provides a useful means of calculating energy changes that are difficult to measure directly. For instance, it is impossible to measure ...

Solved • Oct 31, 2018

Hess's Law

Q. If the reaction to form water were written H2(g) + 1/2O2(g) → H2O(g)large{{ m{H}}_2 left( g ight); + ;frac{1}{2}{ m{O}}_2 left( g ight); ightarrow ...

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. The thermochemical equation for the combustion of butane is shown below. 2C4H10 (g) + 13O2 (g) → 8CO2 (g) + 10H2O (g)     ΔH = -2877 k What is the ...

Solved • Oct 1, 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