CaCO2--> CaO+CO2
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Calculate the pressure of CO2 in an equilibrium process at (a)22 Celsius and (b) 755 Celsius . Assume delta H=177.8KJ/mol and delta S=160.5 J/mol*K for that temeprature range.
My question is do I have to subtract the two temperatures since it says "temperature range" and find delta G using delta H-TdeltaS and then use the equation G=-RTlnK to find K and for the temperature, plug in 22 and 755 separately.
Or do I find delta G for 22 Celsius, and then use G=-RTlnK to find K at that temperature and repeat for 755 C.
I started to do the second way.
for delta g=delta H-TdeltaS=130.4 J
G=-RTlnK
k=e^(-G/RT)=8.34*10^-24
Then I have to find the pressure (Kp)for CO2 which I don't know how to to do after I find K.
To calculate the pressure of CO2 in the equilibrium process, you need to use the equation G = -RTlnK, where G is the change in Gibbs free energy, R is the gas constant (8.314 J/mol*K), T is the temperature in Kelvin, and K is the equilibrium constant.
Since you have the values for delta H and delta S for the temperature range given, you can calculate the change in Gibbs free energy (delta G) using the formula delta G = delta H - T * delta S. However, it's important to note that the given delta H and delta S values are in different units. Delta H is given in kJ/mol and delta S is given in J/mol*K. So, you need to make sure the units are consistent. In this case, you should convert delta H to J/mol by multiplying it by 1000, so delta H = -177.8 kJ/mol * 1000 J/kJ = -177,800 J/mol.
Now, let's calculate the pressure of CO2 at different temperatures:
(a) At 22 degrees Celsius (295 Kelvin):
First, calculate delta G using delta G = delta H - T * delta S:
delta G = -177,800 J/mol - 295 K * 160.5 J/(mol*K) = -177,800 J/mol - 47,297.5 J/mol = -225,097.5 J/mol.
Then, use the equation G = -RTlnK to find K:
K = e^(-delta G / (RT)) = e^(-(-225,097.5 J/mol) / (8.314 J/mol*K * 295 K)) = e^(9.573) ≈ 14522.223.
(b) At 755 degrees Celsius (1028 Kelvin):
Repeat the same steps as above by substituting the temperature value into the equations:
First, calculate delta G using delta G = delta H - T * delta S:
delta G = -177,800 J/mol - 1028 K * 160.5 J/(mol*K) = -177,800 J/mol - 165,084 J/mol = -342,884 J/mol.
Then, use the equation G = -RTlnK to find K:
K = e^(-delta G / (RT)) = e^(-(-342,884 J/mol) / (8.314 J/mol*K * 1028 K)) = e^(33.329) ≈ 2.039 * 10^14.
Now, to determine the pressure of CO2 (Kp), you need to use the equilibrium constant expression for the reaction, which in this case is Kp = (PCO2) / (PCO * PO), where PCO2, PCO, and PO are the partial pressures of CO2, CaO, and CO, respectively.
However, without additional information about the initial partial pressures or the stoichiometric coefficients of the balanced equation, it is not possible to calculate the specific pressure values for CO2 (Kp).
No, you don't subtract the two temperatures. The problem simply states that the delta H and delta S values are assumed to be constant "in that temperature range." The problem is two problems, one at 755 C and the other at 22 C. Don't forget to change T to Kelvin when you use it.
I think you have an error in the equation. You must have intended to write CaCO3 instead of CaCO2. CaCO3 is a solid. CaO is a solid. Therefore, Kp = partial pressure of CO2. So if you know Kp, you automatically know partial pressure of CO2.