I really need this please!!!!!!! :
write the equilibrium-constant expression and calculate the value of the equilibrium constant for each of the following reactions at 298 K.
(a) NaHCO3(s)<--> NaOH(s) + CO2(g)
Answer: Keq = PCO2
(b)Value of the Equilibrium Constant:
Please help me find B
........ deltaHf(KJ/mol)...... d.Gf(KJ/mol)..... d.S(J/mol-K)
NaHCO3(s) -947.7...... -851.8 ......... 102.1
NaOH(s).. -425.6 ...... -379.5 ........ 64.46
CO2(g) .. -393.5 ...... -394.4 ........ 213.6
To find the equilibrium constant expression and value for each reaction, we need to consider the stoichiometry and the expression for the equilibrium constant.
(a) For the reaction: NaHCO3(s) <--> NaOH(s) + CO2(g)
The equilibrium constant expression (Keq) is given by the concentration of the products divided by the concentration of the reactants, each raised to the power of their respective stoichiometric coefficients.
Keq = [CO2] / [NaHCO3]
However, this reaction involves a solid (NaHCO3(s)), which does not have a concentration. We can assume it is constant, so we can omit it from the equilibrium constant expression.
Keq = [CO2]
Therefore, the equilibrium constant expression for this reaction is Keq = PCO2.
(b) To calculate the value of the equilibrium constant, we need to know the standard Gibbs free energy change (∆G°) for the reaction. We can use the equation:
∆G° = -RT ln(Keq)
Where R is the ideal gas constant (8.314 J/mol·K) and T is the temperature in Kelvin (298 K).
For each substance, we can use the given standard enthalpy of formation (∆Hf) and the standard entropy change (∆S) to calculate the standard Gibbs free energy change (∆Gf) using the equation:
∆Gf = ∆Hf - T∆S
Then, we can substitute the calculated ∆Gf values into the equation above to find Keq.
Let's calculate the ∆Gf for each substance:
∆Gf(NaHCO3) = -851.8 kJ/mol - (298 K × 0.1021 kJ/mol·K) = -878.198 kJ/mol
∆Gf(NaOH) = -379.5 kJ/mol - (298 K × 0.06446 kJ/mol·K) = -399.358 kJ/mol
∆Gf(CO2) = -394.4 kJ/mol - (298 K × 0.2136 kJ/mol·K) = -458.6616 kJ/mol
Finally, we can find Keq:
Keq = e^(-∆G° / RT)
Keq = e^(-(-947.7 kJ/mol + 425.6 kJ/mol - 393.5 kJ/mol) / (8.314 J/mol·K × 298 K))
Keq ≈ e^(1247.8 J/mol / 6219.352 J/mol)
Keq ≈ e^0.200515
Keq ≈ 1.221
Therefore, the equilibrium constant (Keq) for the reaction at 298 K is approximately 1.221 for the given reaction.