Given data collected for a liquid.
Equilibrium vapor pressure in torr:
4.6, 17.5, 149.4, 525.8
T in *C
0., 20., 60., 90.
*Find T in K, Find 1/T in K-1 and 1n VP.
*Then make a graph of 1n vapor pressure (1n VP) versus 1/T (where temperature is in units of Kelvins.) Using linear regression analysis (using excel), determine the slope, intercept, r and r squared for the best fit line. Write the equation for the best straight line in terms of 1n VP and 1/T.
*Using the equation you have determined, draw the best straight line among your data points. Show your calculation of the guide points for the best straight line below.
*Determine delta H in joules/mole from the slope calculated in part 1 from linear regression analysis.
*From the equation for the best straight line, determine the equilibrium vapor pressure at 25 *C.
*From the equation for the best fit line, determine the temperature where the equilibrium vapor pressure equals exactly 760 torr, which is the normal boiling point.
#1. We can't draw graphs on these boards.
#2. How much of this do you know how to do.
#3. The 1 you are using for ln should be an ell and not a one (but you're keyboard may not know the difference).
#4. Here is a site that may help you get started. http://www.science.uwaterloo.ca/~cchieh/cact/c123/clausius.html
To solve this problem, we will follow these steps:
Step 1: Convert temperature from °C to K.
To convert a temperature from °C to K, we add 273.15 to the Celsius value.
Equilibrium vapor pressures: 4.6, 17.5, 149.4, 525.8
Temperatures in °C: 0., 20., 60., 90.
Converting temperatures to Kelvin:
T(K) = T(°C) + 273.15
For 0°C: T(K) = 0 + 273.15 = 273.15 K
For 20°C: T(K) = 20 + 273.15 = 293.15 K
For 60°C: T(K) = 60 + 273.15 = 333.15 K
For 90°C: T(K) = 90 + 273.15 = 363.15 K
Step 2: Calculate 1/T in K^(-1).
To calculate 1/T in K^(-1), we take the reciprocal (1/T) for each temperature in Kelvin.
For 273.15 K: 1/T = 1/273.15 = 0.003663
For 293.15 K: 1/T = 1/293.15 = 0.003410
For 333.15 K: 1/T = 1/333.15 = 0.003000
For 363.15 K: 1/T = 1/363.15 = 0.002755
Step 3: Calculate 1n vapor pressure (1n VP).
To calculate 1n VP, we take the natural logarithm (ln) of the equilibrium vapor pressures.
For equilibrium vapor pressure 4.6: 1n VP = ln(4.6) = 1.526056
For equilibrium vapor pressure 17.5: 1n VP = ln(17.5) = 2.862201
For equilibrium vapor pressure 149.4: 1n VP = ln(149.4) = 5.004006
For equilibrium vapor pressure 525.8: 1n VP = ln(525.8) = 6.263398
Step 4: Create a graph of 1n vapor pressure (1n VP) versus 1/T (K^(-1)).
Using Excel or any graphing software, plot the points with 1n VP on the y-axis and 1/T on the x-axis. Connect the points with a straight line to obtain a graph.
Step 5: Perform linear regression analysis.
Using Excel's linear regression analysis tool, input the 1n VP and 1/T data to obtain the slope, intercept, r, and r squared for the best fit line.
Step 6: Write the equation for the best straight line.
The equation for the best straight line can be written as:
1n VP = slope * 1/T + intercept
Step 7: Calculate the guide points for the best straight line.
Using the equation from step 6, substitute the 1/T values to calculate the corresponding 1n VP values for the guide points.
Step 8: Determine delta H in joules/mole using the slope.
Delta H can be determined using the slope of the best fit line. Since the slope is in units of J/(mol * K), delta H is equal to the slope multiplied by the ideal gas constant (R = 8.314 J/(mol * K)).
Step 9: Determine the equilibrium vapor pressure at 25°C.
Using the equation for the best fit line, substitute 1/T = 1/(25 + 273.15) into the equation and solve for 1n VP. The resulting value can be converted back to vapor pressure by taking the exponential function (e^x).
Step 10: Determine the temperature where the equilibrium vapor pressure equals 760 torr (normal boiling point).
Using the equation for the best fit line, substitute the desired vapor pressure of 760 torr into the equation and solve for 1/T. Convert 1/T back to temperature in Kelvin by taking the reciprocal (1/T = 1/(temperature in K)).