The ?H condensation of this liquid in kJ/mole is A.-5.31 B.5.31 C. 44.1 D.-44.1

Question

The ?Hcondensation of this liquid in kJ/mole is

A.-5.31 B.5.31 C. 44.1 D.-44.1

Calculate the normal boiling point of this liquid

A.21.0K B.370.°C C.370.K D.0.00270K

Calculate the vapor pressure in too of the liquid at a temperature of 30.0 °C

A.3.46 B.31.8 C.153 D.78.2

Vapor pressure (torr) and temperature data of a liquid are graphed below. Use this information to answer questions 12-16 3.4 3.3 3.2 3.1 2.9 2.8 2.7 2.6 2.5 y =-5310x + 20.977 0.00332 0.00334 0.00336 0.00338 0.0034 0.00342 0.00344 0.00346 0.00348

Explanation / Answer

(i)

From Claucius Clapeyron equation,

ln(P) = (- delta Hcondensation/R)*(1/T) + C     -------------(1) first equation

The given curve is giving straight line and we know that equation for a straight line is,

y = mx + c ------(2) second equation

from the comparision of these two equations,

y = ln(P) and m (slop)= -delta Hcondensation/R and x is 1/T

The equation given in the graph is, y = - 5310x + 20.977    ----------(3) third equation

from first and third equations,

-delta Hcondensation/R = -5310

negative sign is canceled out since we have it on both sides.

delta Hcondensation/R = 5310

delta Hcondensation = 5310*R

value of R is 8.314

so, delta Hcondensation = 5310 * 8.314 = 44147.34 (This value is in terms of J/mol) so, to convert it into kJ/mol we need to divide it by 1000. Hence, delta Hcondensation = 44.1 kJ/mol

So, the correct option is (C), 44.1 kJ/mol

(ii)

Normal boiling point is the temperature at 760 torr.

From first and third equations...

ln(760) = - 5310*(1/T) + 20.977

6.633 - 20.977 = - 5310*(1/T)

-14.344 = - 5310*(1/T)

negative sign is canceled out since we have it on both sides.

1/T = 14.344/5310 = 0.00270

invert both sides.

T = 1/0.00270 = 370 (This temperature is in kelvin since temperature is taken in kelvin in Claucius Clapeyron equation.

Hence, the correct choice is (C), 370.K

(iii)

We will again do it with the help of the first and third equations.

30 degree C is 30 + 273 = 303K

ln(P) = -5310(1/303) + 20.977

ln(P) = - 17.524+ 20.977

ln(P) = 3.453

P = e^3.452

P = 31.6

Thse closest choice is (B) 31.8

P = e^3.277

P = 26.5

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