Given the following data, determine the heat of vaporization and normal boiling point of ammonia
Temp (K):
200
210
220
230
235
Pressure (respectively)(torr):
65.3
134.3
255.7
456.0
597.0
I tried to figure out using the boiling point elevation formula. I also tried graphing the points to see what I could find. But i am confused of what is the right thing to do.
I would do this.
Use the Clausius-Clapeyron equation. You have T and P at several points. That will allow you to calculate delta Hvap. I might do two or three of the points and take an average. After knowing delta Hvap, one other T/P point can be added. The boiling point will be the T at which P is 760 torr.
Thank you DrBob222!
kioki0iok
To determine the heat of vaporization and normal boiling point of ammonia, we need to use the Clausius-Clapeyron equation, which relates the vapor pressure of a substance to its temperature and heat of vaporization.
The Clausius-Clapeyron equation is given by:
ln(P2/P1) = (-ΔHvap/R) * (1/T2 - 1/T1)
Where:
P1 and P2 are the vapor pressures at temperatures T1 and T2, respectively.
ΔHvap is the heat of vaporization.
R is the ideal gas constant (8.314 J/(mol·K)).
We can use two sets of temperature and pressure data to solve for ΔHvap:
Set 1: T1 = 210 K, P1 = 134.3 torr
Set 2: T2 = 230 K, P2 = 456.0 torr
First, calculate the fraction inside the logarithm:
ln(P2/P1) = ln(456.0/134.3)
Next, rearrange the equation to solve for ΔHvap:
ΔHvap = -(ln(P2/P1) * R) / (1/T2 - 1/T1)
Now, plug in the values:
ΔHvap = -(ln(456.0/134.3) * 8.314) / (1/230 - 1/210)
Calculating this expression gives us the value for the heat of vaporization of ammonia.
To find the normal boiling point, we can use the Antoine equation, which relates the temperature and vapor pressure at the boiling point:
log10(P) = A - (B / (T + C))
Where:
P is the vapor pressure in torr.
T is the temperature in Celsius.
We need to convert the given temperatures from Kelvin to Celsius and use two sets of temperature and pressure data to solve for the boiling point of ammonia:
Set 1: T1 = 235 K, P1 = 597.0 torr
Set 2: T2 = 200 K, P2 = 65.3 torr
For each set, rearrange the equation to solve for T:
T = (B / (A - log10(P))) - C
Plug in the values and calculate T for each set. The lower temperature from the results will be the normal boiling point of ammonia.
By following these calculations, you can determine the heat of vaporization and normal boiling point of ammonia with the given data.