I know the answers to A, B, and C but I dont understand how to do D-G. If you co
ID: 798979 • Letter: I
Question
I know the answers to A, B, and C but I dont understand how to do D-G. If you could help me figure it out that would be awesome. Please help!!
To learn about the relationships between enthalpy, entropy, and free energy To investigate how temperature affects spontaneity Car exhaust plays a major role in the formation of smog, as found in Los Angeles and Houston. Two of the main reactants in the formation of smog arc nitrogen oxides, such as NO, and carbon-containing compounds, such as CO and partially burned hydrocarbons. What thermodynamic forces drive the formation of these smog precursors? You will discover that these reactions proceed only under certain conditions, found in automobile engines. In this activity, you will explore what conditions are required to form these pollutants from molecules readily available in the atmosphere. Another major contributor to smog formation, carbon monoxide (CO), is formed from the following reaction: 2CO2(g) 2CO(g) + O(g) Calculate Delta S for this reaction at 25 degree C. Calculate Delta H for this reaction at 25 degree C. Calculate whether this reaction would be spontaneous at 25 degree C. Calculate the equilibrium constant at room temperature, 298 K. At what temperature docs this reaction become spontaneous? Calculate the equilibrium constant at the temperature from Question c. Why are NO and CO not formed under ambient conditions, but only form under conditions found within an automobile engine? Adapted from the Chom Connections module "How Can We Rechase Air Pollution from Automobiles?" by Howard D Wayne Tikkanam, and Sundra Lau .Explanation / Answer
2 C02 ----> 2 C0 + 02
dHo = 566 kJ /mol
dSo = 172.8
dG0 = dH0 - TdSo
= 566 k - 298 x 172.8
= 566 - 51.49
= 514.51 kJ
as dGo is +Ve the reaction is not spontaneous at 298 K
D) dGo = - RT ln K
514.51 x 1000 = - 8.314 x 298 lnk
k = 6.48 x 10-91
equilibrium constant is 6.48 x 10-91
E) for a reaction to be spontaneous
dG o < 0
dH o - TdSo < 0
T > dHo/dSo
T> 566 x 1000/ 172.8
T > 3275.46 K
the reaction is spontaneous at a temp of 3275.46 K
F) at that temp dG 0= 0
So equilibrium constant is nearly 1
G) the temp in an automobile engine is very high .So they are formed .
As the dHo for the formation of N0 and C0 is highly positive and dSo is positive .So the
reactions are spontaneous at high temp to make dGo negative .
So they are formed in automobile engines where temp is very high