Spectrophotmetric Analysis
Exercise 1
Binary Solid-Liquid Diagram
CHEM 112.1 – 2L
Group 2
I. Data and Results
Table 1.1 Break and arrest temperature of diphenylamine-naphthalene mixture.
Table 1.1. Mole fraction of naphthalene, χB, and corresponding arrest and break temperature at each run. Run number | Mole Fraction,XB | Ave. break temperature, ˚C | Ave. arrest temperature, ˚C | 1 | 1 | 72 | 35.4375 | 2 | 0.868388 | 72 | 35.4375 | 3 | 0.725218 | 62 | 35.4375 | 4 | 0.568895 | 49 | 35.4375 | 5 | 0.397522 | 70 | 35.4375 | 6 | 0 | 45 | 35.4375 | 7 | 0.208813 | 48.5 | 35.4375 | 8 | 0.305919 | 46 | 35.4375 |
I. Discussion
Whenever a mixture is cooled or heated, it undergoes changes in composition. This change is depicted by a phase diagram. It determines whether two or three substances are mutually miscible, whether the equilibrium can exist over a wide range of conditions, or whether the system must be brought to definite temperature, pressure, and composition before equilibrium is established. Interpretation of the phase diagram is usually done with the use of Gibb’s phase rule. It describes the relationship among the number of degrees of freedom (F), the number of components (C), and the number of phases (P) at equilibrium:
F = C – P + 2 eq. 1
The degrees of freedom refer to the number of intensive variables such as temperature, pressure and composition that can be changed without disturbing the number of phases in equilibrium. It cannot have a negative value. All intensive variables are fixed whenever F is equal to zero (invariant). When F=1 (univariant), one of the variables can be varied. When F=2 (bivariant), two of the variables can be varied. Experimentally, phase diagrams are often determined at a fixed atmospheric pressure since it is one of the easiest variable to make constant, thus reduces equation 1 to:
F = C – P + 1 eq. 2
In the experiment, a binary system was considered. Given that the number of components is two, the
Binary Solid-Liquid Diagram
CHEM 112.1 – 2L
Group 2
I. Data and Results
Table 1.1 Break and arrest temperature of diphenylamine-naphthalene mixture.
Table 1.1. Mole fraction of naphthalene, χB, and corresponding arrest and break temperature at each run. Run number | Mole Fraction,XB | Ave. break temperature, ˚C | Ave. arrest temperature, ˚C | 1 | 1 | 72 | 35.4375 | 2 | 0.868388 | 72 | 35.4375 | 3 | 0.725218 | 62 | 35.4375 | 4 | 0.568895 | 49 | 35.4375 | 5 | 0.397522 | 70 | 35.4375 | 6 | 0 | 45 | 35.4375 | 7 | 0.208813 | 48.5 | 35.4375 | 8 | 0.305919 | 46 | 35.4375 |
I. Discussion
Whenever a mixture is cooled or heated, it undergoes changes in composition. This change is depicted by a phase diagram. It determines whether two or three substances are mutually miscible, whether the equilibrium can exist over a wide range of conditions, or whether the system must be brought to definite temperature, pressure, and composition before equilibrium is established. Interpretation of the phase diagram is usually done with the use of Gibb’s phase rule. It describes the relationship among the number of degrees of freedom (F), the number of components (C), and the number of phases (P) at equilibrium:
F = C – P + 2 eq. 1
The degrees of freedom refer to the number of intensive variables such as temperature, pressure and composition that can be changed without disturbing the number of phases in equilibrium. It cannot have a negative value. All intensive variables are fixed whenever F is equal to zero (invariant). When F=1 (univariant), one of the variables can be varied. When F=2 (bivariant), two of the variables can be varied. Experimentally, phase diagrams are often determined at a fixed atmospheric pressure since it is one of the easiest variable to make constant, thus reduces equation 1 to:
F = C – P + 1 eq. 2
In the experiment, a binary system was considered. Given that the number of components is two, the
References: Atkins, PW and JD Paula. 2006. Atkins’ Physical Chemistry. New York: Oxford University Press. Atkins, P.W. 1997. Physical Chemistry. 5th ed. New York: Oxford University Press. pp. 239-242, 254-255. Laidler, KJ and JH Meiser. 1999. Physical Chemistry.3rded. NY: Houghton Mifflin Company. Silbey, R.J. and R.A. Alberty. 2001. Physical Chemistry. 3rd ed. Ney York: John Wiley & Sons, Inc. pp. 207-210.