### Educational Content on Spontaneity of Chemical Reactions**Question 8****Show why reaction (b) is spontaneous only at low temperature, while reaction (a) is always non-spontaneous.****Reactions:**a) \( \text{CH}_4(g) + 2\text{O}_2(g) \rightarrow 2\text{H}_2\text{O}(l) + \text{CO}_2(g) \) (endothermic)b) \( 2\text{C}_2\text{H}_6(g) + 7\text{O}_2(g) \rightarrow 6\text{H}_2\text{O}(l) + 4\text{CO}_2(g) \) (exothermic)### Detailed Explanation**a) Endothermic Reaction:**In the above reaction (a), methane (CH₄) reacts with oxygen (O₂) to form water (H₂O) and carbon dioxide (CO₂). Since this reaction is endothermic, it requires the absorption of heat. For an endothermic reaction, ΔH (change in enthalpy) is positive. Endothermic reactions are usually non-spontaneous because they need continuous energy input to proceed.**b) Exothermic Reaction:**In reaction (b), ethane (C₂H₆) reacts with oxygen (O₂) to yield water (H₂O) and carbon dioxide (CO₂). This is an exothermic reaction, meaning it releases heat into the surroundings. Here, ΔH is negative. However, even exothermic reactions can be non-spontaneous if the temperature conditions are not favorable. Reaction (b) is spontaneous only at low temperatures because low temperatures favor exothermic processes.### Key Concepts- **Spontaneity:** A spontaneous reaction occurs naturally under given conditions. It depends on the changes in enthalpy (ΔH) and entropy (ΔS) of the system, and the temperature (T) as per the Gibbs free energy formula: \[ \Delta G = \Delta H - T\Delta S \] A reaction is spontaneous if ΔG (change in Gibbs free energy) is negative.- **Endothermic Reactions:** Typically require heat absorption from the surroundings. These reactions are often non-spontaneous because

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A Moving to another question will save this response. Question 8 Show why, reaction (b) is spontaneous only at low temperature, while reaction (a) is always non-spontaneous. a) CH4(g) + 202(g) -> 2H2O(l) + CO2(g) (endothermic) b) 2C2H6(g) + 702(g) -> 6H2O(l) + 4CO2(g) (exothermic) For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). Av I Arial V 14px

A Moving to another question will save this response. Question 8 Show why, reaction (b) is spontaneous only at low temperature, while reaction (a) is always non-spontaneous. a) CH4(g) + 202(g) -> 2H2O(l) + CO2(g) (endothermic) b) 2C2H6(g) + 702(g) -> 6H2O(l) + 4CO2(g) (exothermic) For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). Av I Arial V 14px

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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5.) Which of the following statements accurately describes the spontaneity of the reaction below?Al2O3(s) + 2Fe(s) → 2Al(s) + Fe2O3(s) H°rxn = 830.8 kJ/mol, S°rxn = 168 J/mol·K a. The reverse reaction is always spontaneous.b. The reaction is spontaneous above 4945 K.c. The reaction is spontaneous below 4945 K.d. The reaction is always spontaneous.e. There is not enough information to determine.
2H2O(g) ----> 2H2(g) + O2(g) The reaction above is only spontaneous at temperatures above 2000K. Is the reaction endothermic (+ΔH) or exothermic (-ΔH)?
(a) Using Gibb's free energy equation, predict whether at 28.0 °C, the following reaction is spontaneous or not: 4 NH3 (g) + 5 O2 (g) 4 NO (g) + 6 H2O (g) (Given: AU = + 9.08 kJ.mol¬' and AS = + 35.7 JK-' mol-') Hint: Use AU and above equation to calculate AH first. (b) Calculate the Change in Gibb’s Free energy for the following reaction and predict whether the reaction is spontaneous under standard conditions or not? 4 KCIO3 (9) — ЗКСІО4 (9) + КCІ () Given: Molecules дн? (кJ/mol) S°(J/mol.K) KCIO3 (s) -397.7 143.1 KCIO4 (s) -432.8 151.0 KCI (s) -436.7 82.6
For a particular reaction, ΔH = -32 kJ and ΔS = -98 J/K.Assume that ΔH and ΔS do not vary with temperature.(a) At what temperature will the reaction have ΔG = 0?(b) If T is increased from that in part (a), will the reactionbe spontaneous or nonspontaneous?
The element oxygen was prepared by Joseph Priestley in 1774 by heating mercury(II) oxide: HgO(s) → Hg() + 1/2O2(g), AH = 90.84 kJ/mol. Estimate the temperature at which this reaction will become spontaneous under standard state conditions. S'(Hg) = 76.02 J/K mol S(O2) = 205.0 J/K mol C S(HgO) = 70.29 J/K mol 11
Determine whether the following reactions are spontaneous or non-spontaneous. a) N2 (g) + 3 H2 (g) ⟶ 2 NH3 (g), ΔG = -32,960 J b) 2 NH3 (g) ⟶ N2 (g) + 3 H2 (g), ΔG = 32,960 J HINT: The change in free energy (ΔG) for reaction is equal to the difference in free energy between the products (Gproducts) and the reactants (Greactants): ΔG = (Gproducts) - (Greactants) In spontaneous reactions, the free energy of the products (Gproducts) of a reaction is less than the free energy of the reactants (Greactants). When this is the case, will the change in free energy (ΔG) will have a negative value or a positive value?
For each reaction, calculate ΔHrxn°, ΔSrxn°, and ΔGrxn° at 25 °C and state whether or not the reaction is spontaneous. If the reacton is not spontaneous, would a change in temperature make it spontaneous? If so, should the temperature be raised or lowered from 25 °C? 2 CH4(g) → C2H6(g) + H2(g) 2 NH3(g) → N2H4(g) + H2(g)
2 For the synthesis of ammonia where AG = -33.3 kJ/mole, determine whether the reaction is spontaneous at 25 C with the following pressures: PN, = 1.0 atm, PH, = 3.0 atm, PNH, = 0.020 atm N2(8) + 3H2(g) = 2NH3(g)
17.28 From each equation and standard enthalpy, predict whether the reaction will be spontaneous at all temperatures, spontaneous at low temperatures but nonspontaneous at high temperatures, nonspontaneous at low temperatures but spontaneous at high temperatures, or not spontaneous at any temperature. Explain the reasons. (a) 2HgO(s) 2Hg(l) + O2(g) = 90.8 kJ → (b) 4Fe(s) + 302(g) → 2Fe2O3(s) AH = -1648.4 kJ (c) N2(g) + 3Cl2(g) → 2NC13(g) днө — 460 kJ 作答 (d) 2NH4NO3(s) → 2N2(g) + 4H2O(g) + O2(g) AH® = -225.5 kJ
At 1200 oC, the reduction of iron (III) oxide (Fe2O3) to elemental iron is not spontaneous: 2Fe2O3(s) → 4Fe(s) + 3O2(g) rG° = +840 kJ At the same temperature solid carbon spontaneously reacts with oxygen, to form CO2 gas. It is found that by mixing carbon with Fe2O3 at this temperature the reduction can be made to proceed, providing at least 3 moles of carbon are present for every 2 moles of Fe2O3. (a)write a balanced equation for the total reaction (b) Use the reaction stoichiometry to determine an upper limit for rG, i.e. the least negative value possible, for the reaction of carbon with oxygen at this temperature. (+840 is the only delta G value given in the question)
6. For each reaction below, determine the sign of AH and AS. Also state under what conditions the reaction is spontaneous (in the forward direction): (a) never spontaneous, (b) always spontaneous, (c) spontaneous at low temperatures, or (d) spontaneous at high temperatures. 1) C2 (g) → 2 Cl (g) (ii) 2 C2H6 (g) + 7 O2 (g) → 4 CO2 (g) + 6 H2O (g)
1. On the basis of your experience, predict which of the following reactions are spontaneous. 1) NaCl(s)→→ NaCl(/) at 25 °C 2) 2 NaCl(s)→→ 2 Na(s) + Cl₂(g) 3) CO2(g) → CO2(s) at 25 °C 4) CO2(g) → C(s) + O2(g) 5) H₂O(s)→ H₂O() at 25 °C a) 1, 2, and 3 b) 1, 2, and 4 c) 3 and 5 d) 3 e) 5