Question

Problem Set 11 October 11, 2019 CHEM 1252 4. One of synthetic chemistry's "holy grails" is to transform methane, CHe(g), into methanol, CH OH(); the purpose is to create an alternative fuel from the primary component of natural gas. (a) Write a balanced chemical equation, with physical states, for the reaction of methane and oxygen to produce methanol. (b) Calculate AG for this reaction. How would you expect increasing the temperature of the reaction to influence AG? 5. Predict and explain whether the following reactions will be nonspontaneous at all temperatures, or spontaneous at all, low, or high temperatures (a) 2POCla(g) -2PCI (g) + O2(e) 179 1/K Al-572 kJ; AS AHP 286 kJ; AS =-137 J/K (b) 302(g) 20(g) AH -1274 k); AS 180 3/K 4NO(g) +6H20(8) (c) 4NH3(g) + 502(g) -844 k); AS--165 J/K AH (d) 2PDS(s) + 302(g) -2PBO(s) +2SO2(g) (e) The reaction referenced in Question 1

Answer 1

4.

(a) Below is the balanced reaction of methane reacting with oxygen to release carbon dioxide and water and energy.

CH₄ (g) + 2O₂ (g) ---->    CO₂ (g) + 2H₂O (g) + energy

In the above reaction 1 mole of methane in its gaseous form reacts with 2 moles of gaseous oxygen to release 1 mole of carbon dioxide and 2 moles of water molecules as steam and energy,

(b) ΔG° for the above reaction of combustion of methane with oxygen to give carbon dioxide and steam will be
    ΔG° = ΔH - TΔS
Since this reaction is exothermic, ΔH will have a negative value.
For T = 298K
    ΔG° = -802.3 - (298 x -0.005) = -800.8 kJ/mol.

Also as we increase the temperature, ΔG° becomes less negative or we can say ΔG° increases with increase in temperature.