Answer to Calculation Two

The Correct answer was 2

The calculations make use of the equations: 
	DG° = 	-R·T·lnb 
	DG° = 	-ln(10)·R·T·log10(b)  
	DG° = 	DH° - T·DS° 

The answers again were:

1. -190, -214 JK^-1mol^-1
2. 1.9, 25.2 JK^-1mol^-1
3. -5.3, -4.1 JK^-1mol^-1
4. 23, 300 JK^-1mol^-1

First it is necessary to calculate the Delta G° values from the given formation constants and temperature 25° C = 298° K.

For the ammonia complex, Delta G°= -8.314·298·2.303·5.01 kJmol-1, that is -28.6 kJmol^-1.

For the 1,2-diaminoethane complex, Delta G°= -8.314·298·2.303·6.15 kJmol^-1 which corresponds to -35.1 kJmol^-1.

This makes use of the relation between Ln and log10 such that Ln(x) = 2.303 log₁₀ (x).

Then using the second relationship above, delta S can be found.

			    Delta H° - Delta G°
		Delta S° = --------------
				       T

For the ammonia complex this gives 1.9 JK-1mol^-1
and for the 1,2-diaminoethane complex 25.2 JK-1mol^-1,
which are the values given as answer 2.

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May-95, rjl