At what temperature would you expect dinitrogen pentoxide to sublime?
N2O5(s)-->N2O5(g)
N2O5(s)= DELTA H -43.1
N2O5(s)= S (J*K1-*MOL1-)= 178.2
N2O5(g)= DELTA H 13.3
N2O5(g)= S (J*K1-*MOL1-)=355.7
where do i start here?
I believe it is done this way.
N2O5(s) ==> N2O5(g)
I assume the dH values are kJ/mol. Also I assume these are delta Hformation values.
dHrxn = (dH products) - (dH reactants)
dSrxn = (S products) - (S reactants). Remember to change S values to kJ.
Then dGrxn = dHrxn - TdSrxn
Finally, set dGrxn = 0 and solve for T (in kelvin). The answer is approximately 45 C.
To determine the temperature at which dinitrogen pentoxide (N2O5) would sublime, you need to analyze the enthalpy of sublimation and the entropy values for the solid and gaseous forms of N2O5.
Sublimation is the process by which a substance transitions directly from a solid to a gas without passing through the liquid phase. It occurs when the vapor pressure of the solid exceeds the atmospheric pressure at a particular temperature.
In this case, you are given the enthalpy change (ΔH) and entropy (S) values for both the solid and gaseous forms of N2O5. The enthalpy change represents the heat absorbed or released during the transition, while the entropy value represents the disorder in the system.
To determine the temperature at which N2O5 would sublime, you can use the Clausius-Clapeyron equation, which relates the enthalpy change, entropy change, and temperature for phase transitions:
ln(P2/P1) = (ΔH/R) * (1/T1 - 1/T2)
where:
P1 and P2 are the vapor pressures at temperatures T1 and T2,
ΔH is the enthalpy change,
R is the ideal gas constant (8.314 J/(mol·K)),
ln denotes the natural logarithm, and
T1 and T2 are the temperatures.
In this case, we want to find the temperature at which the vapor pressure of the solid N2O5 (P1) becomes equal to the atmospheric pressure (P2), which is typically around 1 atm. Let's denote this temperature as Tsub.
Therefore, the equation can be rearranged to solve for Tsub:
ln(1/P2) = (ΔH/R) * (1/T1 - 1/Tsub)
By plugging in the given values for the enthalpy change and entropy, you can now solve for Tsub. Rearranging the equation further:
Tsub = (ΔH/R) / [(1/T1) - ln(1/P2)]
You would need to substitute the appropriate values into this equation to calculate the temperature at which N2O5 would sublime, where ΔH is the enthalpy change for the sublimation process (-43.1 kJ/mol) and P2 is the atmospheric pressure (1 atm).