5(a) The Joule-Thomson experiment (JTE) is an example of an isenthalpic process i) Define an isenthalpic process. (1 mark) ii) Show using thermodynamic functions that JTE is isenthalpic. (4 marks) iii) Briefly explain what happens when the Joule-Thomson coefficient is zero. (3 marks) (b) i) Sketch a reversed Carnot cycle for a refrigeration system (2 marks) Describe the stages of the cycle in b (i) and write down the expression for q, w ii) and AU for each. (6 marks)

5(a) The Joule-Thomson experiment (JTE) is an example of an isenthalpic process i) Define an isenthalpic process. (1 mark) ii) Show using thermodynamic functions that JTE is isenthalpic. (4 marks) iii) Briefly explain what happens when the Joule-Thomson coefficient is zero. (3 marks) (b) i) Sketch a reversed Carnot cycle for a refrigeration system (2 marks) Describe the stages of the cycle in b (i) and write down the expression for q, w ii) and AU for each. (6 marks)

Living By Chemistry: First Edition Textbook

1st Edition

ISBN:9781559539418

Author:Angelica Stacy

Publisher:Angelica Stacy

ChapterU5: Fire: Energy , Thermodynamics, And Oxidation-reduction

Section: Chapter Questions

Problem SI1RE

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3. Calculate the AH for the reaction C, (graphite) + 2H210) CH, from the following enthalpy changes: Caraphite) + Ozia) Co, AH = -393.5 kJ AH = -571.6 kJ 2H,0 COa + 2H,0 2H, + 0, 2(g) 2(g) CH, + 20, 2(g) AH = -890.4 kJ 4(g) 2(g)
What is the change in enthalpy (in kJ mol-¹) for the following reaction Br₂(1) + 2LIF(s) 2BrF(g) + 2Li(s) 1) 1044 kJmol-¹ 2) 292.65 kJmol-¹ 3) -1044 kJmol-¹ 4) 957 kJmol-¹ 5) -957 kJmol-¹
00 Turkcell 3G 03:22 @ %27D 3. When 120 mg of naphthalene, CH, (s), was burned in a bomb calorimeter the temperature rose by 3.05 K a) Calculate the calorimeter constant. b) By how much will the temperature rise when 10 mg of phenol, C,HOH(s), is bumed in the calorimeter under the same conditions? (AH n.- -5156.3 kJ/mol and Mw CH 128.17 g/mol, AH° CESON = -3054 kJ/mol, Mw CO94.12 g/mol) 4 At 25°C, the density of a 50 % by mass ethanol/water solution is 0.914 g cm. Given that the partial molar volume of water in this solution is 17.4 cm'mol'. What is the partial molar volume of the ethanol? (d 0.789 g/cm': d-1.00 g cm": Mw for water-18 g mot', ethanol-46.07g mot 5. The addition of 5.00 g of a compound to 250 g of naphthalene lowered the freezing point of naphthalene by 0.780 K. Calculate the molar mass of the compound. (K, 694 KAgmol for naphthalene)
(4) 2.50mol of Ar (ideal gas) initially at 298K and P = 1bar is heated until its volume is doubled. Find w done on the gas, q, AU, and AH if the process takes place at constant pressure, and P = Pext- = Find AS, ASsurr, and AStotal for surr spontaneous in those cases? Why? 1000K and Tsurr = 298K. Is the process
(b) What is Hess law? Several reactions and their standard reaction enthalpies at 298.15 K are given here: all k mat Ca+ 1/20s - C 435.1 65.2 The standard enthalpies of combustion of graphite and C2H2(g) are -393.51 and -1299.58 kJ mol-, respec- tively. Calculate the standard enthalpy of formation of CaC2(s) at 25°C.
(a) An ideal gas of mass 4.5 g and molar mass of 17 g.mole-1 occupies 12.7 L at 310 K. Answer the following questions based on the conditions presented. (i) Calculate the work done under a constant external pressure of 30 kPa until the volume of gas has increased by 3.3 L. (ii) Calculate the work done in an isothermal and reversible expansion process resulting in a final volume of 16L. (iii) If the gas has a molar heat capacity of 30.8 J.mol-1.K-1 and is subjected to a constant volume process until it reaches a temperature of 350K, calculate the heat transfer in kJ.mol-1 of the gas. (b) Calculate the standard enthalpy of formation of N2O5 (g) from N2 (g) and O2 (g), in kJ. mol-1, from the following data: 2NO(g) + O2(g) ® 2NO2(g) DH = -114.1 kJ 4NO2(g) + O2(g) ® 2N2O5(g) DH = -110.2 kJ N2(g) + O2(g) ® 2NO(g) DH = +180.5 kJ
The reduction of iron(III) oxide (Fe₂O,) to pure iron during the first step of steelmaking, 4 - 4 Fe(s) + 30, (e) 4 2 Fe,0,(3) is driven by the high-temperature combustion of coke, a purified form of coal: C(s) + O₂(e) co₂(e) Suppose at the temperature of a blast furnace the Gibbs free energies of formation AG, of CO, and Fe₂O, are-413. kl/mol and -826. kJ/mel, respectively. Calculate the maximum mass of pure iron that can be produced by the combustion of 6200. kg of cake. Round your answer to 2 significant digits. A kg 0.P 00 1.60 9
Your answer is partially correct. For the chemical reaction Al203(s) + 3H2(g,p = 1 bar) 2AI(s) + 3H20(1) at T = 298 K, answer each of the following by doing a quantitative calculation of the appropriate thermodynamic function: (a) Is this a spontaneous reaction? AG°reaction i kJ. The reaction is not spontaneous. (b) Does the reaction absorb or release heat? ΔΗreaction - i kJ. The reaction absorbs + heat. (c) Are the products more or less dispersed than the reactants? AS° reaction i J/K. Entropy decreases ÷ so the products are more + dispersed than the reactants. eTextbook and Media Save for Later Attempts: 1 of 3 used Submit Answer
2.3. For a process occurring at constant temperature and pressure, the equation for the Gibbs free energy can be written as: AG AS ΔΗ + AS univ Give the meaning of each term on the right hand side.
6A. State whether each of the following is true or false. Explain your reasoning in each case. (a) q must be zero for an isothermal process (b) q=0 for every cyclic process [A cyclic process is one that begins in one state and undergoes several steps which ultimately bring the system back to the same initial state.] (c) DU=0 for every cyclic process. (d) DT=0 for every adiabatic process in a closed system.
Chose the correct option that represents the change in Gibbs free energy. (A) dG =Eµdn, (B) dG =£un (C) dG =-Eµdn, i (D) dG =µ> dn,
Find the value of x in the following transformation (report the result as a whole number): Fe2O3(s) + 3C(graphite) --> 2Fe(s) + 3CO(g); ΔH = x kJ 4Fe(s) + 3O2(g) --> 2Fe2O3(s); ΔH = -1,403 kJ 2C(graphite) + O2(g) --> 2CO(g); ΔH = -193 kJ