Question 6 of 18 Mapo maumilan learning The vapor pressure, P, of a certain liqu

Question

Question 6 of 18 Mapo maumilan learning The vapor pressure, P, of a certain liquid was measured at two temperatures If you were going to graphically determine the enthalpy of vaporizaton, dHvp, for this liquid, what points would you plot? The data is shown in this table. Number Number T(K) P (kPa) 275 3.79 775 7.02 To avoid rounding errors, use three significant figures in the x values and four significant figures in the y values. point 1 Number Number NOTE: Keep the pressure units in kPa. point 2n Determine the rise, run, and slope of the line formed by these points. slope rise run Number What is the enthalpy of vaporization of this liquid? Numbe J/mol

Explanation / Answer

Measuring dHvap

From the given T and P values,

x = 1/T

y = ln(P)

                       x                              y

point 1       0.00364                     1.33

point 2       0.00129                     1.95

From the given x and y values,

rise = (y2 - y1) = (1.95 - 1.33) = 0.62

run = (x2 - x1) = (0.00129 - 0.00364) = -0.00235

slope = rise/run = 0.62/-0.00235 = -263.83

Enthalpy of vaporisation of this liquid,

dHvap = -slope x R

R = gas constant

So,

dHvap = -(-263.83) x 8.314

            = 2193.48 J/mol

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