Transcript 605 FREEZING POINT DEPRESSION LAB WRITEUP

FREEZING POINT DEPRESSION LAB
1)INTRODUCTION: DISCUSS FREEZING POINT DEPRESSION, MOLALITY,
COLLIGATIVE PROPERTIES, SOLUTE, SOLVENT.
2)DATA,
1) PRESENT A TABLE OF YOUR COOLING CURVE OF LAURIC ACID
WITH BHT.
2) PRESENT THE TABLE OF THE NORMAL FREEZING CURVE OF
LAURIC ACID (mp about 43 degrees).
3)RESULTS;
1) GRAPH ON EXCELL OR OTHER GRAPHING PROGRAM BOTH
COOLING CURVES ON THE SAME GRAPH, USE DIFFERENT
COLORS OR LINE PATTERNS FOR EACH CURVE.
2) DISCUSS THE ▲T OF FREEZING.
FREEZING POINT DEPRESSION LAB
MOLALITY(m) = MOLES SOLUTE (BHT IN THIS LAB)
Kg of SOLVENT (Lauric Acid)
Change in freezing
point between pure
lauric acid + BHT
(from your data from
the two cooling
curves)
Find molality by
dividing grams of BHT
used by the grams of
lauric acid used–
(converted to Kg by
dividing by 1000) NOTE.
GFM of BHT is 220.0
g/mol
MOLALITY
▲TF = kF m
The freezing point
depression constant,
you should calculate
this from your data
SOME POINTERS:
1-The ▲ T is the difference between your depressed freezing point of the
lauric acid-BHT solution and pure lauric acid which melts at about 43o C.
2- Convert the moles of BHT to moles. Then convert the grams of your lauric
acid sample to Kg by dividing by 1000.
3- Solve for Kf.
OBSERVATIONS: list any observations, compare the freezing
point of the pure lauric acid to the lauric-BHT solution
results verbally.
DISCUSSION AND CONCLUSION. Look up the kf of lauric acid
and calculate % error.